forked from Minki/linux
1a55af2e45
In this function we are making use of rq->clock right before the update of the rq clock, let's just call update_rq_clock() just before that to avoid using a stale rq clock value. Signed-off-by: Frederic Weisbecker <fweisbec@gmail.com> Cc: Li Zhong <zhong@linux.vnet.ibm.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: Paul Turner <pjt@google.com> Cc: Mike Galbraith <efault@gmx.de> Signed-off-by: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/1365724262-20142-5-git-send-email-fweisbec@gmail.com Signed-off-by: Ingo Molnar <mingo@kernel.org>
6219 lines
159 KiB
C
6219 lines
159 KiB
C
/*
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* Completely Fair Scheduling (CFS) Class (SCHED_NORMAL/SCHED_BATCH)
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*
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* Copyright (C) 2007 Red Hat, Inc., Ingo Molnar <mingo@redhat.com>
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*
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* Interactivity improvements by Mike Galbraith
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* (C) 2007 Mike Galbraith <efault@gmx.de>
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*
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* Various enhancements by Dmitry Adamushko.
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* (C) 2007 Dmitry Adamushko <dmitry.adamushko@gmail.com>
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*
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* Group scheduling enhancements by Srivatsa Vaddagiri
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* Copyright IBM Corporation, 2007
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* Author: Srivatsa Vaddagiri <vatsa@linux.vnet.ibm.com>
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*
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* Scaled math optimizations by Thomas Gleixner
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* Copyright (C) 2007, Thomas Gleixner <tglx@linutronix.de>
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*
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* Adaptive scheduling granularity, math enhancements by Peter Zijlstra
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* Copyright (C) 2007 Red Hat, Inc., Peter Zijlstra <pzijlstr@redhat.com>
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*/
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#include <linux/latencytop.h>
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#include <linux/sched.h>
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#include <linux/cpumask.h>
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#include <linux/slab.h>
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#include <linux/profile.h>
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#include <linux/interrupt.h>
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#include <linux/mempolicy.h>
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#include <linux/migrate.h>
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#include <linux/task_work.h>
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#include <trace/events/sched.h>
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#include "sched.h"
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/*
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* Targeted preemption latency for CPU-bound tasks:
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* (default: 6ms * (1 + ilog(ncpus)), units: nanoseconds)
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*
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* NOTE: this latency value is not the same as the concept of
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* 'timeslice length' - timeslices in CFS are of variable length
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* and have no persistent notion like in traditional, time-slice
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* based scheduling concepts.
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*
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* (to see the precise effective timeslice length of your workload,
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* run vmstat and monitor the context-switches (cs) field)
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*/
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unsigned int sysctl_sched_latency = 6000000ULL;
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unsigned int normalized_sysctl_sched_latency = 6000000ULL;
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/*
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* The initial- and re-scaling of tunables is configurable
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* (default SCHED_TUNABLESCALING_LOG = *(1+ilog(ncpus))
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*
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* Options are:
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* SCHED_TUNABLESCALING_NONE - unscaled, always *1
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* SCHED_TUNABLESCALING_LOG - scaled logarithmical, *1+ilog(ncpus)
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* SCHED_TUNABLESCALING_LINEAR - scaled linear, *ncpus
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*/
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enum sched_tunable_scaling sysctl_sched_tunable_scaling
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= SCHED_TUNABLESCALING_LOG;
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/*
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* Minimal preemption granularity for CPU-bound tasks:
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* (default: 0.75 msec * (1 + ilog(ncpus)), units: nanoseconds)
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*/
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unsigned int sysctl_sched_min_granularity = 750000ULL;
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unsigned int normalized_sysctl_sched_min_granularity = 750000ULL;
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/*
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* is kept at sysctl_sched_latency / sysctl_sched_min_granularity
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*/
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static unsigned int sched_nr_latency = 8;
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/*
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* After fork, child runs first. If set to 0 (default) then
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* parent will (try to) run first.
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*/
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unsigned int sysctl_sched_child_runs_first __read_mostly;
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/*
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* SCHED_OTHER wake-up granularity.
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* (default: 1 msec * (1 + ilog(ncpus)), units: nanoseconds)
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*
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* This option delays the preemption effects of decoupled workloads
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* and reduces their over-scheduling. Synchronous workloads will still
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* have immediate wakeup/sleep latencies.
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*/
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unsigned int sysctl_sched_wakeup_granularity = 1000000UL;
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unsigned int normalized_sysctl_sched_wakeup_granularity = 1000000UL;
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const_debug unsigned int sysctl_sched_migration_cost = 500000UL;
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/*
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* The exponential sliding window over which load is averaged for shares
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* distribution.
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* (default: 10msec)
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*/
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unsigned int __read_mostly sysctl_sched_shares_window = 10000000UL;
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#ifdef CONFIG_CFS_BANDWIDTH
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/*
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* Amount of runtime to allocate from global (tg) to local (per-cfs_rq) pool
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* each time a cfs_rq requests quota.
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*
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* Note: in the case that the slice exceeds the runtime remaining (either due
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* to consumption or the quota being specified to be smaller than the slice)
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* we will always only issue the remaining available time.
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*
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* default: 5 msec, units: microseconds
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*/
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unsigned int sysctl_sched_cfs_bandwidth_slice = 5000UL;
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#endif
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static inline void update_load_add(struct load_weight *lw, unsigned long inc)
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{
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lw->weight += inc;
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lw->inv_weight = 0;
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}
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static inline void update_load_sub(struct load_weight *lw, unsigned long dec)
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{
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lw->weight -= dec;
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lw->inv_weight = 0;
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}
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static inline void update_load_set(struct load_weight *lw, unsigned long w)
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{
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lw->weight = w;
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lw->inv_weight = 0;
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}
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/*
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* Increase the granularity value when there are more CPUs,
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* because with more CPUs the 'effective latency' as visible
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* to users decreases. But the relationship is not linear,
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* so pick a second-best guess by going with the log2 of the
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* number of CPUs.
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*
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* This idea comes from the SD scheduler of Con Kolivas:
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*/
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static int get_update_sysctl_factor(void)
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{
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unsigned int cpus = min_t(int, num_online_cpus(), 8);
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unsigned int factor;
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switch (sysctl_sched_tunable_scaling) {
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case SCHED_TUNABLESCALING_NONE:
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factor = 1;
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break;
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case SCHED_TUNABLESCALING_LINEAR:
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factor = cpus;
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break;
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case SCHED_TUNABLESCALING_LOG:
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default:
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factor = 1 + ilog2(cpus);
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break;
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}
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return factor;
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}
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static void update_sysctl(void)
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{
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unsigned int factor = get_update_sysctl_factor();
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#define SET_SYSCTL(name) \
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(sysctl_##name = (factor) * normalized_sysctl_##name)
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SET_SYSCTL(sched_min_granularity);
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SET_SYSCTL(sched_latency);
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SET_SYSCTL(sched_wakeup_granularity);
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#undef SET_SYSCTL
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}
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void sched_init_granularity(void)
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{
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update_sysctl();
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}
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#if BITS_PER_LONG == 32
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# define WMULT_CONST (~0UL)
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#else
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# define WMULT_CONST (1UL << 32)
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#endif
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#define WMULT_SHIFT 32
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/*
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* Shift right and round:
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*/
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#define SRR(x, y) (((x) + (1UL << ((y) - 1))) >> (y))
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/*
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* delta *= weight / lw
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*/
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static unsigned long
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calc_delta_mine(unsigned long delta_exec, unsigned long weight,
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struct load_weight *lw)
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{
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u64 tmp;
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/*
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* weight can be less than 2^SCHED_LOAD_RESOLUTION for task group sched
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* entities since MIN_SHARES = 2. Treat weight as 1 if less than
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* 2^SCHED_LOAD_RESOLUTION.
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*/
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if (likely(weight > (1UL << SCHED_LOAD_RESOLUTION)))
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tmp = (u64)delta_exec * scale_load_down(weight);
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else
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tmp = (u64)delta_exec;
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if (!lw->inv_weight) {
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unsigned long w = scale_load_down(lw->weight);
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if (BITS_PER_LONG > 32 && unlikely(w >= WMULT_CONST))
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lw->inv_weight = 1;
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else if (unlikely(!w))
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lw->inv_weight = WMULT_CONST;
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else
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lw->inv_weight = WMULT_CONST / w;
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}
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/*
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* Check whether we'd overflow the 64-bit multiplication:
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*/
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if (unlikely(tmp > WMULT_CONST))
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tmp = SRR(SRR(tmp, WMULT_SHIFT/2) * lw->inv_weight,
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WMULT_SHIFT/2);
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else
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tmp = SRR(tmp * lw->inv_weight, WMULT_SHIFT);
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return (unsigned long)min(tmp, (u64)(unsigned long)LONG_MAX);
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}
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const struct sched_class fair_sched_class;
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/**************************************************************
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* CFS operations on generic schedulable entities:
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*/
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#ifdef CONFIG_FAIR_GROUP_SCHED
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/* cpu runqueue to which this cfs_rq is attached */
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static inline struct rq *rq_of(struct cfs_rq *cfs_rq)
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{
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return cfs_rq->rq;
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}
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/* An entity is a task if it doesn't "own" a runqueue */
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#define entity_is_task(se) (!se->my_q)
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static inline struct task_struct *task_of(struct sched_entity *se)
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{
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#ifdef CONFIG_SCHED_DEBUG
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WARN_ON_ONCE(!entity_is_task(se));
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#endif
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return container_of(se, struct task_struct, se);
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}
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/* Walk up scheduling entities hierarchy */
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#define for_each_sched_entity(se) \
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for (; se; se = se->parent)
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static inline struct cfs_rq *task_cfs_rq(struct task_struct *p)
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{
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return p->se.cfs_rq;
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}
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/* runqueue on which this entity is (to be) queued */
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static inline struct cfs_rq *cfs_rq_of(struct sched_entity *se)
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{
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return se->cfs_rq;
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}
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/* runqueue "owned" by this group */
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static inline struct cfs_rq *group_cfs_rq(struct sched_entity *grp)
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{
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return grp->my_q;
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}
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static void update_cfs_rq_blocked_load(struct cfs_rq *cfs_rq,
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int force_update);
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static inline void list_add_leaf_cfs_rq(struct cfs_rq *cfs_rq)
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{
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if (!cfs_rq->on_list) {
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/*
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* Ensure we either appear before our parent (if already
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* enqueued) or force our parent to appear after us when it is
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* enqueued. The fact that we always enqueue bottom-up
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* reduces this to two cases.
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*/
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if (cfs_rq->tg->parent &&
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cfs_rq->tg->parent->cfs_rq[cpu_of(rq_of(cfs_rq))]->on_list) {
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list_add_rcu(&cfs_rq->leaf_cfs_rq_list,
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&rq_of(cfs_rq)->leaf_cfs_rq_list);
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} else {
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list_add_tail_rcu(&cfs_rq->leaf_cfs_rq_list,
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&rq_of(cfs_rq)->leaf_cfs_rq_list);
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}
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cfs_rq->on_list = 1;
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/* We should have no load, but we need to update last_decay. */
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update_cfs_rq_blocked_load(cfs_rq, 0);
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}
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}
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static inline void list_del_leaf_cfs_rq(struct cfs_rq *cfs_rq)
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{
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if (cfs_rq->on_list) {
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list_del_rcu(&cfs_rq->leaf_cfs_rq_list);
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cfs_rq->on_list = 0;
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}
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}
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/* Iterate thr' all leaf cfs_rq's on a runqueue */
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#define for_each_leaf_cfs_rq(rq, cfs_rq) \
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list_for_each_entry_rcu(cfs_rq, &rq->leaf_cfs_rq_list, leaf_cfs_rq_list)
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/* Do the two (enqueued) entities belong to the same group ? */
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static inline int
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is_same_group(struct sched_entity *se, struct sched_entity *pse)
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{
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if (se->cfs_rq == pse->cfs_rq)
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return 1;
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return 0;
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}
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static inline struct sched_entity *parent_entity(struct sched_entity *se)
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{
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return se->parent;
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}
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/* return depth at which a sched entity is present in the hierarchy */
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static inline int depth_se(struct sched_entity *se)
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{
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int depth = 0;
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for_each_sched_entity(se)
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depth++;
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return depth;
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}
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static void
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find_matching_se(struct sched_entity **se, struct sched_entity **pse)
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{
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int se_depth, pse_depth;
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/*
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* preemption test can be made between sibling entities who are in the
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* same cfs_rq i.e who have a common parent. Walk up the hierarchy of
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* both tasks until we find their ancestors who are siblings of common
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* parent.
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*/
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/* First walk up until both entities are at same depth */
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se_depth = depth_se(*se);
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pse_depth = depth_se(*pse);
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while (se_depth > pse_depth) {
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se_depth--;
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*se = parent_entity(*se);
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}
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while (pse_depth > se_depth) {
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pse_depth--;
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*pse = parent_entity(*pse);
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}
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while (!is_same_group(*se, *pse)) {
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*se = parent_entity(*se);
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*pse = parent_entity(*pse);
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}
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}
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#else /* !CONFIG_FAIR_GROUP_SCHED */
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static inline struct task_struct *task_of(struct sched_entity *se)
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{
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return container_of(se, struct task_struct, se);
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}
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static inline struct rq *rq_of(struct cfs_rq *cfs_rq)
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{
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return container_of(cfs_rq, struct rq, cfs);
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}
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#define entity_is_task(se) 1
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#define for_each_sched_entity(se) \
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for (; se; se = NULL)
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static inline struct cfs_rq *task_cfs_rq(struct task_struct *p)
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{
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return &task_rq(p)->cfs;
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}
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static inline struct cfs_rq *cfs_rq_of(struct sched_entity *se)
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{
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struct task_struct *p = task_of(se);
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struct rq *rq = task_rq(p);
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return &rq->cfs;
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}
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/* runqueue "owned" by this group */
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static inline struct cfs_rq *group_cfs_rq(struct sched_entity *grp)
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{
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return NULL;
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}
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static inline void list_add_leaf_cfs_rq(struct cfs_rq *cfs_rq)
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{
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}
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static inline void list_del_leaf_cfs_rq(struct cfs_rq *cfs_rq)
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{
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}
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#define for_each_leaf_cfs_rq(rq, cfs_rq) \
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for (cfs_rq = &rq->cfs; cfs_rq; cfs_rq = NULL)
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static inline int
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is_same_group(struct sched_entity *se, struct sched_entity *pse)
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{
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return 1;
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}
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static inline struct sched_entity *parent_entity(struct sched_entity *se)
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{
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return NULL;
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}
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static inline void
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find_matching_se(struct sched_entity **se, struct sched_entity **pse)
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{
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}
|
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#endif /* CONFIG_FAIR_GROUP_SCHED */
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static __always_inline
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void account_cfs_rq_runtime(struct cfs_rq *cfs_rq, unsigned long delta_exec);
|
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|
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/**************************************************************
|
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* Scheduling class tree data structure manipulation methods:
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*/
|
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static inline u64 max_vruntime(u64 max_vruntime, u64 vruntime)
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{
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s64 delta = (s64)(vruntime - max_vruntime);
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if (delta > 0)
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max_vruntime = vruntime;
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return max_vruntime;
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}
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|
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static inline u64 min_vruntime(u64 min_vruntime, u64 vruntime)
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{
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s64 delta = (s64)(vruntime - min_vruntime);
|
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if (delta < 0)
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min_vruntime = vruntime;
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return min_vruntime;
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}
|
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|
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static inline int entity_before(struct sched_entity *a,
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struct sched_entity *b)
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{
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return (s64)(a->vruntime - b->vruntime) < 0;
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}
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|
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static void update_min_vruntime(struct cfs_rq *cfs_rq)
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{
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u64 vruntime = cfs_rq->min_vruntime;
|
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|
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if (cfs_rq->curr)
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vruntime = cfs_rq->curr->vruntime;
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|
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if (cfs_rq->rb_leftmost) {
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struct sched_entity *se = rb_entry(cfs_rq->rb_leftmost,
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struct sched_entity,
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run_node);
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if (!cfs_rq->curr)
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vruntime = se->vruntime;
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else
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vruntime = min_vruntime(vruntime, se->vruntime);
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}
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|
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/* ensure we never gain time by being placed backwards. */
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cfs_rq->min_vruntime = max_vruntime(cfs_rq->min_vruntime, vruntime);
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#ifndef CONFIG_64BIT
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smp_wmb();
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cfs_rq->min_vruntime_copy = cfs_rq->min_vruntime;
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#endif
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}
|
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|
|
/*
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* Enqueue an entity into the rb-tree:
|
|
*/
|
|
static void __enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se)
|
|
{
|
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struct rb_node **link = &cfs_rq->tasks_timeline.rb_node;
|
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struct rb_node *parent = NULL;
|
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struct sched_entity *entry;
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int leftmost = 1;
|
|
|
|
/*
|
|
* Find the right place in the rbtree:
|
|
*/
|
|
while (*link) {
|
|
parent = *link;
|
|
entry = rb_entry(parent, struct sched_entity, run_node);
|
|
/*
|
|
* We dont care about collisions. Nodes with
|
|
* the same key stay together.
|
|
*/
|
|
if (entity_before(se, entry)) {
|
|
link = &parent->rb_left;
|
|
} else {
|
|
link = &parent->rb_right;
|
|
leftmost = 0;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Maintain a cache of leftmost tree entries (it is frequently
|
|
* used):
|
|
*/
|
|
if (leftmost)
|
|
cfs_rq->rb_leftmost = &se->run_node;
|
|
|
|
rb_link_node(&se->run_node, parent, link);
|
|
rb_insert_color(&se->run_node, &cfs_rq->tasks_timeline);
|
|
}
|
|
|
|
static void __dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se)
|
|
{
|
|
if (cfs_rq->rb_leftmost == &se->run_node) {
|
|
struct rb_node *next_node;
|
|
|
|
next_node = rb_next(&se->run_node);
|
|
cfs_rq->rb_leftmost = next_node;
|
|
}
|
|
|
|
rb_erase(&se->run_node, &cfs_rq->tasks_timeline);
|
|
}
|
|
|
|
struct sched_entity *__pick_first_entity(struct cfs_rq *cfs_rq)
|
|
{
|
|
struct rb_node *left = cfs_rq->rb_leftmost;
|
|
|
|
if (!left)
|
|
return NULL;
|
|
|
|
return rb_entry(left, struct sched_entity, run_node);
|
|
}
|
|
|
|
static struct sched_entity *__pick_next_entity(struct sched_entity *se)
|
|
{
|
|
struct rb_node *next = rb_next(&se->run_node);
|
|
|
|
if (!next)
|
|
return NULL;
|
|
|
|
return rb_entry(next, struct sched_entity, run_node);
|
|
}
|
|
|
|
#ifdef CONFIG_SCHED_DEBUG
|
|
struct sched_entity *__pick_last_entity(struct cfs_rq *cfs_rq)
|
|
{
|
|
struct rb_node *last = rb_last(&cfs_rq->tasks_timeline);
|
|
|
|
if (!last)
|
|
return NULL;
|
|
|
|
return rb_entry(last, struct sched_entity, run_node);
|
|
}
|
|
|
|
/**************************************************************
|
|
* Scheduling class statistics methods:
|
|
*/
|
|
|
|
int sched_proc_update_handler(struct ctl_table *table, int write,
|
|
void __user *buffer, size_t *lenp,
|
|
loff_t *ppos)
|
|
{
|
|
int ret = proc_dointvec_minmax(table, write, buffer, lenp, ppos);
|
|
int factor = get_update_sysctl_factor();
|
|
|
|
if (ret || !write)
|
|
return ret;
|
|
|
|
sched_nr_latency = DIV_ROUND_UP(sysctl_sched_latency,
|
|
sysctl_sched_min_granularity);
|
|
|
|
#define WRT_SYSCTL(name) \
|
|
(normalized_sysctl_##name = sysctl_##name / (factor))
|
|
WRT_SYSCTL(sched_min_granularity);
|
|
WRT_SYSCTL(sched_latency);
|
|
WRT_SYSCTL(sched_wakeup_granularity);
|
|
#undef WRT_SYSCTL
|
|
|
|
return 0;
|
|
}
|
|
#endif
|
|
|
|
/*
|
|
* delta /= w
|
|
*/
|
|
static inline unsigned long
|
|
calc_delta_fair(unsigned long delta, struct sched_entity *se)
|
|
{
|
|
if (unlikely(se->load.weight != NICE_0_LOAD))
|
|
delta = calc_delta_mine(delta, NICE_0_LOAD, &se->load);
|
|
|
|
return delta;
|
|
}
|
|
|
|
/*
|
|
* The idea is to set a period in which each task runs once.
|
|
*
|
|
* When there are too many tasks (sched_nr_latency) we have to stretch
|
|
* this period because otherwise the slices get too small.
|
|
*
|
|
* p = (nr <= nl) ? l : l*nr/nl
|
|
*/
|
|
static u64 __sched_period(unsigned long nr_running)
|
|
{
|
|
u64 period = sysctl_sched_latency;
|
|
unsigned long nr_latency = sched_nr_latency;
|
|
|
|
if (unlikely(nr_running > nr_latency)) {
|
|
period = sysctl_sched_min_granularity;
|
|
period *= nr_running;
|
|
}
|
|
|
|
return period;
|
|
}
|
|
|
|
/*
|
|
* We calculate the wall-time slice from the period by taking a part
|
|
* proportional to the weight.
|
|
*
|
|
* s = p*P[w/rw]
|
|
*/
|
|
static u64 sched_slice(struct cfs_rq *cfs_rq, struct sched_entity *se)
|
|
{
|
|
u64 slice = __sched_period(cfs_rq->nr_running + !se->on_rq);
|
|
|
|
for_each_sched_entity(se) {
|
|
struct load_weight *load;
|
|
struct load_weight lw;
|
|
|
|
cfs_rq = cfs_rq_of(se);
|
|
load = &cfs_rq->load;
|
|
|
|
if (unlikely(!se->on_rq)) {
|
|
lw = cfs_rq->load;
|
|
|
|
update_load_add(&lw, se->load.weight);
|
|
load = &lw;
|
|
}
|
|
slice = calc_delta_mine(slice, se->load.weight, load);
|
|
}
|
|
return slice;
|
|
}
|
|
|
|
/*
|
|
* We calculate the vruntime slice of a to-be-inserted task.
|
|
*
|
|
* vs = s/w
|
|
*/
|
|
static u64 sched_vslice(struct cfs_rq *cfs_rq, struct sched_entity *se)
|
|
{
|
|
return calc_delta_fair(sched_slice(cfs_rq, se), se);
|
|
}
|
|
|
|
/*
|
|
* Update the current task's runtime statistics. Skip current tasks that
|
|
* are not in our scheduling class.
|
|
*/
|
|
static inline void
|
|
__update_curr(struct cfs_rq *cfs_rq, struct sched_entity *curr,
|
|
unsigned long delta_exec)
|
|
{
|
|
unsigned long delta_exec_weighted;
|
|
|
|
schedstat_set(curr->statistics.exec_max,
|
|
max((u64)delta_exec, curr->statistics.exec_max));
|
|
|
|
curr->sum_exec_runtime += delta_exec;
|
|
schedstat_add(cfs_rq, exec_clock, delta_exec);
|
|
delta_exec_weighted = calc_delta_fair(delta_exec, curr);
|
|
|
|
curr->vruntime += delta_exec_weighted;
|
|
update_min_vruntime(cfs_rq);
|
|
}
|
|
|
|
static void update_curr(struct cfs_rq *cfs_rq)
|
|
{
|
|
struct sched_entity *curr = cfs_rq->curr;
|
|
u64 now = rq_of(cfs_rq)->clock_task;
|
|
unsigned long delta_exec;
|
|
|
|
if (unlikely(!curr))
|
|
return;
|
|
|
|
/*
|
|
* Get the amount of time the current task was running
|
|
* since the last time we changed load (this cannot
|
|
* overflow on 32 bits):
|
|
*/
|
|
delta_exec = (unsigned long)(now - curr->exec_start);
|
|
if (!delta_exec)
|
|
return;
|
|
|
|
__update_curr(cfs_rq, curr, delta_exec);
|
|
curr->exec_start = now;
|
|
|
|
if (entity_is_task(curr)) {
|
|
struct task_struct *curtask = task_of(curr);
|
|
|
|
trace_sched_stat_runtime(curtask, delta_exec, curr->vruntime);
|
|
cpuacct_charge(curtask, delta_exec);
|
|
account_group_exec_runtime(curtask, delta_exec);
|
|
}
|
|
|
|
account_cfs_rq_runtime(cfs_rq, delta_exec);
|
|
}
|
|
|
|
static inline void
|
|
update_stats_wait_start(struct cfs_rq *cfs_rq, struct sched_entity *se)
|
|
{
|
|
schedstat_set(se->statistics.wait_start, rq_of(cfs_rq)->clock);
|
|
}
|
|
|
|
/*
|
|
* Task is being enqueued - update stats:
|
|
*/
|
|
static void update_stats_enqueue(struct cfs_rq *cfs_rq, struct sched_entity *se)
|
|
{
|
|
/*
|
|
* Are we enqueueing a waiting task? (for current tasks
|
|
* a dequeue/enqueue event is a NOP)
|
|
*/
|
|
if (se != cfs_rq->curr)
|
|
update_stats_wait_start(cfs_rq, se);
|
|
}
|
|
|
|
static void
|
|
update_stats_wait_end(struct cfs_rq *cfs_rq, struct sched_entity *se)
|
|
{
|
|
schedstat_set(se->statistics.wait_max, max(se->statistics.wait_max,
|
|
rq_of(cfs_rq)->clock - se->statistics.wait_start));
|
|
schedstat_set(se->statistics.wait_count, se->statistics.wait_count + 1);
|
|
schedstat_set(se->statistics.wait_sum, se->statistics.wait_sum +
|
|
rq_of(cfs_rq)->clock - se->statistics.wait_start);
|
|
#ifdef CONFIG_SCHEDSTATS
|
|
if (entity_is_task(se)) {
|
|
trace_sched_stat_wait(task_of(se),
|
|
rq_of(cfs_rq)->clock - se->statistics.wait_start);
|
|
}
|
|
#endif
|
|
schedstat_set(se->statistics.wait_start, 0);
|
|
}
|
|
|
|
static inline void
|
|
update_stats_dequeue(struct cfs_rq *cfs_rq, struct sched_entity *se)
|
|
{
|
|
/*
|
|
* Mark the end of the wait period if dequeueing a
|
|
* waiting task:
|
|
*/
|
|
if (se != cfs_rq->curr)
|
|
update_stats_wait_end(cfs_rq, se);
|
|
}
|
|
|
|
/*
|
|
* We are picking a new current task - update its stats:
|
|
*/
|
|
static inline void
|
|
update_stats_curr_start(struct cfs_rq *cfs_rq, struct sched_entity *se)
|
|
{
|
|
/*
|
|
* We are starting a new run period:
|
|
*/
|
|
se->exec_start = rq_of(cfs_rq)->clock_task;
|
|
}
|
|
|
|
/**************************************************
|
|
* Scheduling class queueing methods:
|
|
*/
|
|
|
|
#ifdef CONFIG_NUMA_BALANCING
|
|
/*
|
|
* numa task sample period in ms
|
|
*/
|
|
unsigned int sysctl_numa_balancing_scan_period_min = 100;
|
|
unsigned int sysctl_numa_balancing_scan_period_max = 100*50;
|
|
unsigned int sysctl_numa_balancing_scan_period_reset = 100*600;
|
|
|
|
/* Portion of address space to scan in MB */
|
|
unsigned int sysctl_numa_balancing_scan_size = 256;
|
|
|
|
/* Scan @scan_size MB every @scan_period after an initial @scan_delay in ms */
|
|
unsigned int sysctl_numa_balancing_scan_delay = 1000;
|
|
|
|
static void task_numa_placement(struct task_struct *p)
|
|
{
|
|
int seq;
|
|
|
|
if (!p->mm) /* for example, ksmd faulting in a user's mm */
|
|
return;
|
|
seq = ACCESS_ONCE(p->mm->numa_scan_seq);
|
|
if (p->numa_scan_seq == seq)
|
|
return;
|
|
p->numa_scan_seq = seq;
|
|
|
|
/* FIXME: Scheduling placement policy hints go here */
|
|
}
|
|
|
|
/*
|
|
* Got a PROT_NONE fault for a page on @node.
|
|
*/
|
|
void task_numa_fault(int node, int pages, bool migrated)
|
|
{
|
|
struct task_struct *p = current;
|
|
|
|
if (!sched_feat_numa(NUMA))
|
|
return;
|
|
|
|
/* FIXME: Allocate task-specific structure for placement policy here */
|
|
|
|
/*
|
|
* If pages are properly placed (did not migrate) then scan slower.
|
|
* This is reset periodically in case of phase changes
|
|
*/
|
|
if (!migrated)
|
|
p->numa_scan_period = min(sysctl_numa_balancing_scan_period_max,
|
|
p->numa_scan_period + jiffies_to_msecs(10));
|
|
|
|
task_numa_placement(p);
|
|
}
|
|
|
|
static void reset_ptenuma_scan(struct task_struct *p)
|
|
{
|
|
ACCESS_ONCE(p->mm->numa_scan_seq)++;
|
|
p->mm->numa_scan_offset = 0;
|
|
}
|
|
|
|
/*
|
|
* The expensive part of numa migration is done from task_work context.
|
|
* Triggered from task_tick_numa().
|
|
*/
|
|
void task_numa_work(struct callback_head *work)
|
|
{
|
|
unsigned long migrate, next_scan, now = jiffies;
|
|
struct task_struct *p = current;
|
|
struct mm_struct *mm = p->mm;
|
|
struct vm_area_struct *vma;
|
|
unsigned long start, end;
|
|
long pages;
|
|
|
|
WARN_ON_ONCE(p != container_of(work, struct task_struct, numa_work));
|
|
|
|
work->next = work; /* protect against double add */
|
|
/*
|
|
* Who cares about NUMA placement when they're dying.
|
|
*
|
|
* NOTE: make sure not to dereference p->mm before this check,
|
|
* exit_task_work() happens _after_ exit_mm() so we could be called
|
|
* without p->mm even though we still had it when we enqueued this
|
|
* work.
|
|
*/
|
|
if (p->flags & PF_EXITING)
|
|
return;
|
|
|
|
/*
|
|
* We do not care about task placement until a task runs on a node
|
|
* other than the first one used by the address space. This is
|
|
* largely because migrations are driven by what CPU the task
|
|
* is running on. If it's never scheduled on another node, it'll
|
|
* not migrate so why bother trapping the fault.
|
|
*/
|
|
if (mm->first_nid == NUMA_PTE_SCAN_INIT)
|
|
mm->first_nid = numa_node_id();
|
|
if (mm->first_nid != NUMA_PTE_SCAN_ACTIVE) {
|
|
/* Are we running on a new node yet? */
|
|
if (numa_node_id() == mm->first_nid &&
|
|
!sched_feat_numa(NUMA_FORCE))
|
|
return;
|
|
|
|
mm->first_nid = NUMA_PTE_SCAN_ACTIVE;
|
|
}
|
|
|
|
/*
|
|
* Reset the scan period if enough time has gone by. Objective is that
|
|
* scanning will be reduced if pages are properly placed. As tasks
|
|
* can enter different phases this needs to be re-examined. Lacking
|
|
* proper tracking of reference behaviour, this blunt hammer is used.
|
|
*/
|
|
migrate = mm->numa_next_reset;
|
|
if (time_after(now, migrate)) {
|
|
p->numa_scan_period = sysctl_numa_balancing_scan_period_min;
|
|
next_scan = now + msecs_to_jiffies(sysctl_numa_balancing_scan_period_reset);
|
|
xchg(&mm->numa_next_reset, next_scan);
|
|
}
|
|
|
|
/*
|
|
* Enforce maximal scan/migration frequency..
|
|
*/
|
|
migrate = mm->numa_next_scan;
|
|
if (time_before(now, migrate))
|
|
return;
|
|
|
|
if (p->numa_scan_period == 0)
|
|
p->numa_scan_period = sysctl_numa_balancing_scan_period_min;
|
|
|
|
next_scan = now + msecs_to_jiffies(p->numa_scan_period);
|
|
if (cmpxchg(&mm->numa_next_scan, migrate, next_scan) != migrate)
|
|
return;
|
|
|
|
/*
|
|
* Do not set pte_numa if the current running node is rate-limited.
|
|
* This loses statistics on the fault but if we are unwilling to
|
|
* migrate to this node, it is less likely we can do useful work
|
|
*/
|
|
if (migrate_ratelimited(numa_node_id()))
|
|
return;
|
|
|
|
start = mm->numa_scan_offset;
|
|
pages = sysctl_numa_balancing_scan_size;
|
|
pages <<= 20 - PAGE_SHIFT; /* MB in pages */
|
|
if (!pages)
|
|
return;
|
|
|
|
down_read(&mm->mmap_sem);
|
|
vma = find_vma(mm, start);
|
|
if (!vma) {
|
|
reset_ptenuma_scan(p);
|
|
start = 0;
|
|
vma = mm->mmap;
|
|
}
|
|
for (; vma; vma = vma->vm_next) {
|
|
if (!vma_migratable(vma))
|
|
continue;
|
|
|
|
/* Skip small VMAs. They are not likely to be of relevance */
|
|
if (vma->vm_end - vma->vm_start < HPAGE_SIZE)
|
|
continue;
|
|
|
|
do {
|
|
start = max(start, vma->vm_start);
|
|
end = ALIGN(start + (pages << PAGE_SHIFT), HPAGE_SIZE);
|
|
end = min(end, vma->vm_end);
|
|
pages -= change_prot_numa(vma, start, end);
|
|
|
|
start = end;
|
|
if (pages <= 0)
|
|
goto out;
|
|
} while (end != vma->vm_end);
|
|
}
|
|
|
|
out:
|
|
/*
|
|
* It is possible to reach the end of the VMA list but the last few VMAs are
|
|
* not guaranteed to the vma_migratable. If they are not, we would find the
|
|
* !migratable VMA on the next scan but not reset the scanner to the start
|
|
* so check it now.
|
|
*/
|
|
if (vma)
|
|
mm->numa_scan_offset = start;
|
|
else
|
|
reset_ptenuma_scan(p);
|
|
up_read(&mm->mmap_sem);
|
|
}
|
|
|
|
/*
|
|
* Drive the periodic memory faults..
|
|
*/
|
|
void task_tick_numa(struct rq *rq, struct task_struct *curr)
|
|
{
|
|
struct callback_head *work = &curr->numa_work;
|
|
u64 period, now;
|
|
|
|
/*
|
|
* We don't care about NUMA placement if we don't have memory.
|
|
*/
|
|
if (!curr->mm || (curr->flags & PF_EXITING) || work->next != work)
|
|
return;
|
|
|
|
/*
|
|
* Using runtime rather than walltime has the dual advantage that
|
|
* we (mostly) drive the selection from busy threads and that the
|
|
* task needs to have done some actual work before we bother with
|
|
* NUMA placement.
|
|
*/
|
|
now = curr->se.sum_exec_runtime;
|
|
period = (u64)curr->numa_scan_period * NSEC_PER_MSEC;
|
|
|
|
if (now - curr->node_stamp > period) {
|
|
if (!curr->node_stamp)
|
|
curr->numa_scan_period = sysctl_numa_balancing_scan_period_min;
|
|
curr->node_stamp = now;
|
|
|
|
if (!time_before(jiffies, curr->mm->numa_next_scan)) {
|
|
init_task_work(work, task_numa_work); /* TODO: move this into sched_fork() */
|
|
task_work_add(curr, work, true);
|
|
}
|
|
}
|
|
}
|
|
#else
|
|
static void task_tick_numa(struct rq *rq, struct task_struct *curr)
|
|
{
|
|
}
|
|
#endif /* CONFIG_NUMA_BALANCING */
|
|
|
|
static void
|
|
account_entity_enqueue(struct cfs_rq *cfs_rq, struct sched_entity *se)
|
|
{
|
|
update_load_add(&cfs_rq->load, se->load.weight);
|
|
if (!parent_entity(se))
|
|
update_load_add(&rq_of(cfs_rq)->load, se->load.weight);
|
|
#ifdef CONFIG_SMP
|
|
if (entity_is_task(se))
|
|
list_add(&se->group_node, &rq_of(cfs_rq)->cfs_tasks);
|
|
#endif
|
|
cfs_rq->nr_running++;
|
|
}
|
|
|
|
static void
|
|
account_entity_dequeue(struct cfs_rq *cfs_rq, struct sched_entity *se)
|
|
{
|
|
update_load_sub(&cfs_rq->load, se->load.weight);
|
|
if (!parent_entity(se))
|
|
update_load_sub(&rq_of(cfs_rq)->load, se->load.weight);
|
|
if (entity_is_task(se))
|
|
list_del_init(&se->group_node);
|
|
cfs_rq->nr_running--;
|
|
}
|
|
|
|
#ifdef CONFIG_FAIR_GROUP_SCHED
|
|
# ifdef CONFIG_SMP
|
|
static inline long calc_tg_weight(struct task_group *tg, struct cfs_rq *cfs_rq)
|
|
{
|
|
long tg_weight;
|
|
|
|
/*
|
|
* Use this CPU's actual weight instead of the last load_contribution
|
|
* to gain a more accurate current total weight. See
|
|
* update_cfs_rq_load_contribution().
|
|
*/
|
|
tg_weight = atomic64_read(&tg->load_avg);
|
|
tg_weight -= cfs_rq->tg_load_contrib;
|
|
tg_weight += cfs_rq->load.weight;
|
|
|
|
return tg_weight;
|
|
}
|
|
|
|
static long calc_cfs_shares(struct cfs_rq *cfs_rq, struct task_group *tg)
|
|
{
|
|
long tg_weight, load, shares;
|
|
|
|
tg_weight = calc_tg_weight(tg, cfs_rq);
|
|
load = cfs_rq->load.weight;
|
|
|
|
shares = (tg->shares * load);
|
|
if (tg_weight)
|
|
shares /= tg_weight;
|
|
|
|
if (shares < MIN_SHARES)
|
|
shares = MIN_SHARES;
|
|
if (shares > tg->shares)
|
|
shares = tg->shares;
|
|
|
|
return shares;
|
|
}
|
|
# else /* CONFIG_SMP */
|
|
static inline long calc_cfs_shares(struct cfs_rq *cfs_rq, struct task_group *tg)
|
|
{
|
|
return tg->shares;
|
|
}
|
|
# endif /* CONFIG_SMP */
|
|
static void reweight_entity(struct cfs_rq *cfs_rq, struct sched_entity *se,
|
|
unsigned long weight)
|
|
{
|
|
if (se->on_rq) {
|
|
/* commit outstanding execution time */
|
|
if (cfs_rq->curr == se)
|
|
update_curr(cfs_rq);
|
|
account_entity_dequeue(cfs_rq, se);
|
|
}
|
|
|
|
update_load_set(&se->load, weight);
|
|
|
|
if (se->on_rq)
|
|
account_entity_enqueue(cfs_rq, se);
|
|
}
|
|
|
|
static inline int throttled_hierarchy(struct cfs_rq *cfs_rq);
|
|
|
|
static void update_cfs_shares(struct cfs_rq *cfs_rq)
|
|
{
|
|
struct task_group *tg;
|
|
struct sched_entity *se;
|
|
long shares;
|
|
|
|
tg = cfs_rq->tg;
|
|
se = tg->se[cpu_of(rq_of(cfs_rq))];
|
|
if (!se || throttled_hierarchy(cfs_rq))
|
|
return;
|
|
#ifndef CONFIG_SMP
|
|
if (likely(se->load.weight == tg->shares))
|
|
return;
|
|
#endif
|
|
shares = calc_cfs_shares(cfs_rq, tg);
|
|
|
|
reweight_entity(cfs_rq_of(se), se, shares);
|
|
}
|
|
#else /* CONFIG_FAIR_GROUP_SCHED */
|
|
static inline void update_cfs_shares(struct cfs_rq *cfs_rq)
|
|
{
|
|
}
|
|
#endif /* CONFIG_FAIR_GROUP_SCHED */
|
|
|
|
/* Only depends on SMP, FAIR_GROUP_SCHED may be removed when useful in lb */
|
|
#if defined(CONFIG_SMP) && defined(CONFIG_FAIR_GROUP_SCHED)
|
|
/*
|
|
* We choose a half-life close to 1 scheduling period.
|
|
* Note: The tables below are dependent on this value.
|
|
*/
|
|
#define LOAD_AVG_PERIOD 32
|
|
#define LOAD_AVG_MAX 47742 /* maximum possible load avg */
|
|
#define LOAD_AVG_MAX_N 345 /* number of full periods to produce LOAD_MAX_AVG */
|
|
|
|
/* Precomputed fixed inverse multiplies for multiplication by y^n */
|
|
static const u32 runnable_avg_yN_inv[] = {
|
|
0xffffffff, 0xfa83b2da, 0xf5257d14, 0xefe4b99a, 0xeac0c6e6, 0xe5b906e6,
|
|
0xe0ccdeeb, 0xdbfbb796, 0xd744fcc9, 0xd2a81d91, 0xce248c14, 0xc9b9bd85,
|
|
0xc5672a10, 0xc12c4cc9, 0xbd08a39e, 0xb8fbaf46, 0xb504f333, 0xb123f581,
|
|
0xad583ee9, 0xa9a15ab4, 0xa5fed6a9, 0xa2704302, 0x9ef5325f, 0x9b8d39b9,
|
|
0x9837f050, 0x94f4efa8, 0x91c3d373, 0x8ea4398a, 0x8b95c1e3, 0x88980e80,
|
|
0x85aac367, 0x82cd8698,
|
|
};
|
|
|
|
/*
|
|
* Precomputed \Sum y^k { 1<=k<=n }. These are floor(true_value) to prevent
|
|
* over-estimates when re-combining.
|
|
*/
|
|
static const u32 runnable_avg_yN_sum[] = {
|
|
0, 1002, 1982, 2941, 3880, 4798, 5697, 6576, 7437, 8279, 9103,
|
|
9909,10698,11470,12226,12966,13690,14398,15091,15769,16433,17082,
|
|
17718,18340,18949,19545,20128,20698,21256,21802,22336,22859,23371,
|
|
};
|
|
|
|
/*
|
|
* Approximate:
|
|
* val * y^n, where y^32 ~= 0.5 (~1 scheduling period)
|
|
*/
|
|
static __always_inline u64 decay_load(u64 val, u64 n)
|
|
{
|
|
unsigned int local_n;
|
|
|
|
if (!n)
|
|
return val;
|
|
else if (unlikely(n > LOAD_AVG_PERIOD * 63))
|
|
return 0;
|
|
|
|
/* after bounds checking we can collapse to 32-bit */
|
|
local_n = n;
|
|
|
|
/*
|
|
* As y^PERIOD = 1/2, we can combine
|
|
* y^n = 1/2^(n/PERIOD) * k^(n%PERIOD)
|
|
* With a look-up table which covers k^n (n<PERIOD)
|
|
*
|
|
* To achieve constant time decay_load.
|
|
*/
|
|
if (unlikely(local_n >= LOAD_AVG_PERIOD)) {
|
|
val >>= local_n / LOAD_AVG_PERIOD;
|
|
local_n %= LOAD_AVG_PERIOD;
|
|
}
|
|
|
|
val *= runnable_avg_yN_inv[local_n];
|
|
/* We don't use SRR here since we always want to round down. */
|
|
return val >> 32;
|
|
}
|
|
|
|
/*
|
|
* For updates fully spanning n periods, the contribution to runnable
|
|
* average will be: \Sum 1024*y^n
|
|
*
|
|
* We can compute this reasonably efficiently by combining:
|
|
* y^PERIOD = 1/2 with precomputed \Sum 1024*y^n {for n <PERIOD}
|
|
*/
|
|
static u32 __compute_runnable_contrib(u64 n)
|
|
{
|
|
u32 contrib = 0;
|
|
|
|
if (likely(n <= LOAD_AVG_PERIOD))
|
|
return runnable_avg_yN_sum[n];
|
|
else if (unlikely(n >= LOAD_AVG_MAX_N))
|
|
return LOAD_AVG_MAX;
|
|
|
|
/* Compute \Sum k^n combining precomputed values for k^i, \Sum k^j */
|
|
do {
|
|
contrib /= 2; /* y^LOAD_AVG_PERIOD = 1/2 */
|
|
contrib += runnable_avg_yN_sum[LOAD_AVG_PERIOD];
|
|
|
|
n -= LOAD_AVG_PERIOD;
|
|
} while (n > LOAD_AVG_PERIOD);
|
|
|
|
contrib = decay_load(contrib, n);
|
|
return contrib + runnable_avg_yN_sum[n];
|
|
}
|
|
|
|
/*
|
|
* We can represent the historical contribution to runnable average as the
|
|
* coefficients of a geometric series. To do this we sub-divide our runnable
|
|
* history into segments of approximately 1ms (1024us); label the segment that
|
|
* occurred N-ms ago p_N, with p_0 corresponding to the current period, e.g.
|
|
*
|
|
* [<- 1024us ->|<- 1024us ->|<- 1024us ->| ...
|
|
* p0 p1 p2
|
|
* (now) (~1ms ago) (~2ms ago)
|
|
*
|
|
* Let u_i denote the fraction of p_i that the entity was runnable.
|
|
*
|
|
* We then designate the fractions u_i as our co-efficients, yielding the
|
|
* following representation of historical load:
|
|
* u_0 + u_1*y + u_2*y^2 + u_3*y^3 + ...
|
|
*
|
|
* We choose y based on the with of a reasonably scheduling period, fixing:
|
|
* y^32 = 0.5
|
|
*
|
|
* This means that the contribution to load ~32ms ago (u_32) will be weighted
|
|
* approximately half as much as the contribution to load within the last ms
|
|
* (u_0).
|
|
*
|
|
* When a period "rolls over" and we have new u_0`, multiplying the previous
|
|
* sum again by y is sufficient to update:
|
|
* load_avg = u_0` + y*(u_0 + u_1*y + u_2*y^2 + ... )
|
|
* = u_0 + u_1*y + u_2*y^2 + ... [re-labeling u_i --> u_{i+1}]
|
|
*/
|
|
static __always_inline int __update_entity_runnable_avg(u64 now,
|
|
struct sched_avg *sa,
|
|
int runnable)
|
|
{
|
|
u64 delta, periods;
|
|
u32 runnable_contrib;
|
|
int delta_w, decayed = 0;
|
|
|
|
delta = now - sa->last_runnable_update;
|
|
/*
|
|
* This should only happen when time goes backwards, which it
|
|
* unfortunately does during sched clock init when we swap over to TSC.
|
|
*/
|
|
if ((s64)delta < 0) {
|
|
sa->last_runnable_update = now;
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Use 1024ns as the unit of measurement since it's a reasonable
|
|
* approximation of 1us and fast to compute.
|
|
*/
|
|
delta >>= 10;
|
|
if (!delta)
|
|
return 0;
|
|
sa->last_runnable_update = now;
|
|
|
|
/* delta_w is the amount already accumulated against our next period */
|
|
delta_w = sa->runnable_avg_period % 1024;
|
|
if (delta + delta_w >= 1024) {
|
|
/* period roll-over */
|
|
decayed = 1;
|
|
|
|
/*
|
|
* Now that we know we're crossing a period boundary, figure
|
|
* out how much from delta we need to complete the current
|
|
* period and accrue it.
|
|
*/
|
|
delta_w = 1024 - delta_w;
|
|
if (runnable)
|
|
sa->runnable_avg_sum += delta_w;
|
|
sa->runnable_avg_period += delta_w;
|
|
|
|
delta -= delta_w;
|
|
|
|
/* Figure out how many additional periods this update spans */
|
|
periods = delta / 1024;
|
|
delta %= 1024;
|
|
|
|
sa->runnable_avg_sum = decay_load(sa->runnable_avg_sum,
|
|
periods + 1);
|
|
sa->runnable_avg_period = decay_load(sa->runnable_avg_period,
|
|
periods + 1);
|
|
|
|
/* Efficiently calculate \sum (1..n_period) 1024*y^i */
|
|
runnable_contrib = __compute_runnable_contrib(periods);
|
|
if (runnable)
|
|
sa->runnable_avg_sum += runnable_contrib;
|
|
sa->runnable_avg_period += runnable_contrib;
|
|
}
|
|
|
|
/* Remainder of delta accrued against u_0` */
|
|
if (runnable)
|
|
sa->runnable_avg_sum += delta;
|
|
sa->runnable_avg_period += delta;
|
|
|
|
return decayed;
|
|
}
|
|
|
|
/* Synchronize an entity's decay with its parenting cfs_rq.*/
|
|
static inline u64 __synchronize_entity_decay(struct sched_entity *se)
|
|
{
|
|
struct cfs_rq *cfs_rq = cfs_rq_of(se);
|
|
u64 decays = atomic64_read(&cfs_rq->decay_counter);
|
|
|
|
decays -= se->avg.decay_count;
|
|
if (!decays)
|
|
return 0;
|
|
|
|
se->avg.load_avg_contrib = decay_load(se->avg.load_avg_contrib, decays);
|
|
se->avg.decay_count = 0;
|
|
|
|
return decays;
|
|
}
|
|
|
|
#ifdef CONFIG_FAIR_GROUP_SCHED
|
|
static inline void __update_cfs_rq_tg_load_contrib(struct cfs_rq *cfs_rq,
|
|
int force_update)
|
|
{
|
|
struct task_group *tg = cfs_rq->tg;
|
|
s64 tg_contrib;
|
|
|
|
tg_contrib = cfs_rq->runnable_load_avg + cfs_rq->blocked_load_avg;
|
|
tg_contrib -= cfs_rq->tg_load_contrib;
|
|
|
|
if (force_update || abs64(tg_contrib) > cfs_rq->tg_load_contrib / 8) {
|
|
atomic64_add(tg_contrib, &tg->load_avg);
|
|
cfs_rq->tg_load_contrib += tg_contrib;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Aggregate cfs_rq runnable averages into an equivalent task_group
|
|
* representation for computing load contributions.
|
|
*/
|
|
static inline void __update_tg_runnable_avg(struct sched_avg *sa,
|
|
struct cfs_rq *cfs_rq)
|
|
{
|
|
struct task_group *tg = cfs_rq->tg;
|
|
long contrib;
|
|
|
|
/* The fraction of a cpu used by this cfs_rq */
|
|
contrib = div_u64(sa->runnable_avg_sum << NICE_0_SHIFT,
|
|
sa->runnable_avg_period + 1);
|
|
contrib -= cfs_rq->tg_runnable_contrib;
|
|
|
|
if (abs(contrib) > cfs_rq->tg_runnable_contrib / 64) {
|
|
atomic_add(contrib, &tg->runnable_avg);
|
|
cfs_rq->tg_runnable_contrib += contrib;
|
|
}
|
|
}
|
|
|
|
static inline void __update_group_entity_contrib(struct sched_entity *se)
|
|
{
|
|
struct cfs_rq *cfs_rq = group_cfs_rq(se);
|
|
struct task_group *tg = cfs_rq->tg;
|
|
int runnable_avg;
|
|
|
|
u64 contrib;
|
|
|
|
contrib = cfs_rq->tg_load_contrib * tg->shares;
|
|
se->avg.load_avg_contrib = div64_u64(contrib,
|
|
atomic64_read(&tg->load_avg) + 1);
|
|
|
|
/*
|
|
* For group entities we need to compute a correction term in the case
|
|
* that they are consuming <1 cpu so that we would contribute the same
|
|
* load as a task of equal weight.
|
|
*
|
|
* Explicitly co-ordinating this measurement would be expensive, but
|
|
* fortunately the sum of each cpus contribution forms a usable
|
|
* lower-bound on the true value.
|
|
*
|
|
* Consider the aggregate of 2 contributions. Either they are disjoint
|
|
* (and the sum represents true value) or they are disjoint and we are
|
|
* understating by the aggregate of their overlap.
|
|
*
|
|
* Extending this to N cpus, for a given overlap, the maximum amount we
|
|
* understand is then n_i(n_i+1)/2 * w_i where n_i is the number of
|
|
* cpus that overlap for this interval and w_i is the interval width.
|
|
*
|
|
* On a small machine; the first term is well-bounded which bounds the
|
|
* total error since w_i is a subset of the period. Whereas on a
|
|
* larger machine, while this first term can be larger, if w_i is the
|
|
* of consequential size guaranteed to see n_i*w_i quickly converge to
|
|
* our upper bound of 1-cpu.
|
|
*/
|
|
runnable_avg = atomic_read(&tg->runnable_avg);
|
|
if (runnable_avg < NICE_0_LOAD) {
|
|
se->avg.load_avg_contrib *= runnable_avg;
|
|
se->avg.load_avg_contrib >>= NICE_0_SHIFT;
|
|
}
|
|
}
|
|
#else
|
|
static inline void __update_cfs_rq_tg_load_contrib(struct cfs_rq *cfs_rq,
|
|
int force_update) {}
|
|
static inline void __update_tg_runnable_avg(struct sched_avg *sa,
|
|
struct cfs_rq *cfs_rq) {}
|
|
static inline void __update_group_entity_contrib(struct sched_entity *se) {}
|
|
#endif
|
|
|
|
static inline void __update_task_entity_contrib(struct sched_entity *se)
|
|
{
|
|
u32 contrib;
|
|
|
|
/* avoid overflowing a 32-bit type w/ SCHED_LOAD_SCALE */
|
|
contrib = se->avg.runnable_avg_sum * scale_load_down(se->load.weight);
|
|
contrib /= (se->avg.runnable_avg_period + 1);
|
|
se->avg.load_avg_contrib = scale_load(contrib);
|
|
}
|
|
|
|
/* Compute the current contribution to load_avg by se, return any delta */
|
|
static long __update_entity_load_avg_contrib(struct sched_entity *se)
|
|
{
|
|
long old_contrib = se->avg.load_avg_contrib;
|
|
|
|
if (entity_is_task(se)) {
|
|
__update_task_entity_contrib(se);
|
|
} else {
|
|
__update_tg_runnable_avg(&se->avg, group_cfs_rq(se));
|
|
__update_group_entity_contrib(se);
|
|
}
|
|
|
|
return se->avg.load_avg_contrib - old_contrib;
|
|
}
|
|
|
|
static inline void subtract_blocked_load_contrib(struct cfs_rq *cfs_rq,
|
|
long load_contrib)
|
|
{
|
|
if (likely(load_contrib < cfs_rq->blocked_load_avg))
|
|
cfs_rq->blocked_load_avg -= load_contrib;
|
|
else
|
|
cfs_rq->blocked_load_avg = 0;
|
|
}
|
|
|
|
static inline u64 cfs_rq_clock_task(struct cfs_rq *cfs_rq);
|
|
|
|
/* Update a sched_entity's runnable average */
|
|
static inline void update_entity_load_avg(struct sched_entity *se,
|
|
int update_cfs_rq)
|
|
{
|
|
struct cfs_rq *cfs_rq = cfs_rq_of(se);
|
|
long contrib_delta;
|
|
u64 now;
|
|
|
|
/*
|
|
* For a group entity we need to use their owned cfs_rq_clock_task() in
|
|
* case they are the parent of a throttled hierarchy.
|
|
*/
|
|
if (entity_is_task(se))
|
|
now = cfs_rq_clock_task(cfs_rq);
|
|
else
|
|
now = cfs_rq_clock_task(group_cfs_rq(se));
|
|
|
|
if (!__update_entity_runnable_avg(now, &se->avg, se->on_rq))
|
|
return;
|
|
|
|
contrib_delta = __update_entity_load_avg_contrib(se);
|
|
|
|
if (!update_cfs_rq)
|
|
return;
|
|
|
|
if (se->on_rq)
|
|
cfs_rq->runnable_load_avg += contrib_delta;
|
|
else
|
|
subtract_blocked_load_contrib(cfs_rq, -contrib_delta);
|
|
}
|
|
|
|
/*
|
|
* Decay the load contributed by all blocked children and account this so that
|
|
* their contribution may appropriately discounted when they wake up.
|
|
*/
|
|
static void update_cfs_rq_blocked_load(struct cfs_rq *cfs_rq, int force_update)
|
|
{
|
|
u64 now = cfs_rq_clock_task(cfs_rq) >> 20;
|
|
u64 decays;
|
|
|
|
decays = now - cfs_rq->last_decay;
|
|
if (!decays && !force_update)
|
|
return;
|
|
|
|
if (atomic64_read(&cfs_rq->removed_load)) {
|
|
u64 removed_load = atomic64_xchg(&cfs_rq->removed_load, 0);
|
|
subtract_blocked_load_contrib(cfs_rq, removed_load);
|
|
}
|
|
|
|
if (decays) {
|
|
cfs_rq->blocked_load_avg = decay_load(cfs_rq->blocked_load_avg,
|
|
decays);
|
|
atomic64_add(decays, &cfs_rq->decay_counter);
|
|
cfs_rq->last_decay = now;
|
|
}
|
|
|
|
__update_cfs_rq_tg_load_contrib(cfs_rq, force_update);
|
|
}
|
|
|
|
static inline void update_rq_runnable_avg(struct rq *rq, int runnable)
|
|
{
|
|
__update_entity_runnable_avg(rq->clock_task, &rq->avg, runnable);
|
|
__update_tg_runnable_avg(&rq->avg, &rq->cfs);
|
|
}
|
|
|
|
/* Add the load generated by se into cfs_rq's child load-average */
|
|
static inline void enqueue_entity_load_avg(struct cfs_rq *cfs_rq,
|
|
struct sched_entity *se,
|
|
int wakeup)
|
|
{
|
|
/*
|
|
* We track migrations using entity decay_count <= 0, on a wake-up
|
|
* migration we use a negative decay count to track the remote decays
|
|
* accumulated while sleeping.
|
|
*/
|
|
if (unlikely(se->avg.decay_count <= 0)) {
|
|
se->avg.last_runnable_update = rq_of(cfs_rq)->clock_task;
|
|
if (se->avg.decay_count) {
|
|
/*
|
|
* In a wake-up migration we have to approximate the
|
|
* time sleeping. This is because we can't synchronize
|
|
* clock_task between the two cpus, and it is not
|
|
* guaranteed to be read-safe. Instead, we can
|
|
* approximate this using our carried decays, which are
|
|
* explicitly atomically readable.
|
|
*/
|
|
se->avg.last_runnable_update -= (-se->avg.decay_count)
|
|
<< 20;
|
|
update_entity_load_avg(se, 0);
|
|
/* Indicate that we're now synchronized and on-rq */
|
|
se->avg.decay_count = 0;
|
|
}
|
|
wakeup = 0;
|
|
} else {
|
|
__synchronize_entity_decay(se);
|
|
}
|
|
|
|
/* migrated tasks did not contribute to our blocked load */
|
|
if (wakeup) {
|
|
subtract_blocked_load_contrib(cfs_rq, se->avg.load_avg_contrib);
|
|
update_entity_load_avg(se, 0);
|
|
}
|
|
|
|
cfs_rq->runnable_load_avg += se->avg.load_avg_contrib;
|
|
/* we force update consideration on load-balancer moves */
|
|
update_cfs_rq_blocked_load(cfs_rq, !wakeup);
|
|
}
|
|
|
|
/*
|
|
* Remove se's load from this cfs_rq child load-average, if the entity is
|
|
* transitioning to a blocked state we track its projected decay using
|
|
* blocked_load_avg.
|
|
*/
|
|
static inline void dequeue_entity_load_avg(struct cfs_rq *cfs_rq,
|
|
struct sched_entity *se,
|
|
int sleep)
|
|
{
|
|
update_entity_load_avg(se, 1);
|
|
/* we force update consideration on load-balancer moves */
|
|
update_cfs_rq_blocked_load(cfs_rq, !sleep);
|
|
|
|
cfs_rq->runnable_load_avg -= se->avg.load_avg_contrib;
|
|
if (sleep) {
|
|
cfs_rq->blocked_load_avg += se->avg.load_avg_contrib;
|
|
se->avg.decay_count = atomic64_read(&cfs_rq->decay_counter);
|
|
} /* migrations, e.g. sleep=0 leave decay_count == 0 */
|
|
}
|
|
|
|
/*
|
|
* Update the rq's load with the elapsed running time before entering
|
|
* idle. if the last scheduled task is not a CFS task, idle_enter will
|
|
* be the only way to update the runnable statistic.
|
|
*/
|
|
void idle_enter_fair(struct rq *this_rq)
|
|
{
|
|
update_rq_runnable_avg(this_rq, 1);
|
|
}
|
|
|
|
/*
|
|
* Update the rq's load with the elapsed idle time before a task is
|
|
* scheduled. if the newly scheduled task is not a CFS task, idle_exit will
|
|
* be the only way to update the runnable statistic.
|
|
*/
|
|
void idle_exit_fair(struct rq *this_rq)
|
|
{
|
|
update_rq_runnable_avg(this_rq, 0);
|
|
}
|
|
|
|
#else
|
|
static inline void update_entity_load_avg(struct sched_entity *se,
|
|
int update_cfs_rq) {}
|
|
static inline void update_rq_runnable_avg(struct rq *rq, int runnable) {}
|
|
static inline void enqueue_entity_load_avg(struct cfs_rq *cfs_rq,
|
|
struct sched_entity *se,
|
|
int wakeup) {}
|
|
static inline void dequeue_entity_load_avg(struct cfs_rq *cfs_rq,
|
|
struct sched_entity *se,
|
|
int sleep) {}
|
|
static inline void update_cfs_rq_blocked_load(struct cfs_rq *cfs_rq,
|
|
int force_update) {}
|
|
#endif
|
|
|
|
static void enqueue_sleeper(struct cfs_rq *cfs_rq, struct sched_entity *se)
|
|
{
|
|
#ifdef CONFIG_SCHEDSTATS
|
|
struct task_struct *tsk = NULL;
|
|
|
|
if (entity_is_task(se))
|
|
tsk = task_of(se);
|
|
|
|
if (se->statistics.sleep_start) {
|
|
u64 delta = rq_of(cfs_rq)->clock - se->statistics.sleep_start;
|
|
|
|
if ((s64)delta < 0)
|
|
delta = 0;
|
|
|
|
if (unlikely(delta > se->statistics.sleep_max))
|
|
se->statistics.sleep_max = delta;
|
|
|
|
se->statistics.sleep_start = 0;
|
|
se->statistics.sum_sleep_runtime += delta;
|
|
|
|
if (tsk) {
|
|
account_scheduler_latency(tsk, delta >> 10, 1);
|
|
trace_sched_stat_sleep(tsk, delta);
|
|
}
|
|
}
|
|
if (se->statistics.block_start) {
|
|
u64 delta = rq_of(cfs_rq)->clock - se->statistics.block_start;
|
|
|
|
if ((s64)delta < 0)
|
|
delta = 0;
|
|
|
|
if (unlikely(delta > se->statistics.block_max))
|
|
se->statistics.block_max = delta;
|
|
|
|
se->statistics.block_start = 0;
|
|
se->statistics.sum_sleep_runtime += delta;
|
|
|
|
if (tsk) {
|
|
if (tsk->in_iowait) {
|
|
se->statistics.iowait_sum += delta;
|
|
se->statistics.iowait_count++;
|
|
trace_sched_stat_iowait(tsk, delta);
|
|
}
|
|
|
|
trace_sched_stat_blocked(tsk, delta);
|
|
|
|
/*
|
|
* Blocking time is in units of nanosecs, so shift by
|
|
* 20 to get a milliseconds-range estimation of the
|
|
* amount of time that the task spent sleeping:
|
|
*/
|
|
if (unlikely(prof_on == SLEEP_PROFILING)) {
|
|
profile_hits(SLEEP_PROFILING,
|
|
(void *)get_wchan(tsk),
|
|
delta >> 20);
|
|
}
|
|
account_scheduler_latency(tsk, delta >> 10, 0);
|
|
}
|
|
}
|
|
#endif
|
|
}
|
|
|
|
static void check_spread(struct cfs_rq *cfs_rq, struct sched_entity *se)
|
|
{
|
|
#ifdef CONFIG_SCHED_DEBUG
|
|
s64 d = se->vruntime - cfs_rq->min_vruntime;
|
|
|
|
if (d < 0)
|
|
d = -d;
|
|
|
|
if (d > 3*sysctl_sched_latency)
|
|
schedstat_inc(cfs_rq, nr_spread_over);
|
|
#endif
|
|
}
|
|
|
|
static void
|
|
place_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int initial)
|
|
{
|
|
u64 vruntime = cfs_rq->min_vruntime;
|
|
|
|
/*
|
|
* The 'current' period is already promised to the current tasks,
|
|
* however the extra weight of the new task will slow them down a
|
|
* little, place the new task so that it fits in the slot that
|
|
* stays open at the end.
|
|
*/
|
|
if (initial && sched_feat(START_DEBIT))
|
|
vruntime += sched_vslice(cfs_rq, se);
|
|
|
|
/* sleeps up to a single latency don't count. */
|
|
if (!initial) {
|
|
unsigned long thresh = sysctl_sched_latency;
|
|
|
|
/*
|
|
* Halve their sleep time's effect, to allow
|
|
* for a gentler effect of sleepers:
|
|
*/
|
|
if (sched_feat(GENTLE_FAIR_SLEEPERS))
|
|
thresh >>= 1;
|
|
|
|
vruntime -= thresh;
|
|
}
|
|
|
|
/* ensure we never gain time by being placed backwards. */
|
|
se->vruntime = max_vruntime(se->vruntime, vruntime);
|
|
}
|
|
|
|
static void check_enqueue_throttle(struct cfs_rq *cfs_rq);
|
|
|
|
static void
|
|
enqueue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags)
|
|
{
|
|
/*
|
|
* Update the normalized vruntime before updating min_vruntime
|
|
* through callig update_curr().
|
|
*/
|
|
if (!(flags & ENQUEUE_WAKEUP) || (flags & ENQUEUE_WAKING))
|
|
se->vruntime += cfs_rq->min_vruntime;
|
|
|
|
/*
|
|
* Update run-time statistics of the 'current'.
|
|
*/
|
|
update_curr(cfs_rq);
|
|
enqueue_entity_load_avg(cfs_rq, se, flags & ENQUEUE_WAKEUP);
|
|
account_entity_enqueue(cfs_rq, se);
|
|
update_cfs_shares(cfs_rq);
|
|
|
|
if (flags & ENQUEUE_WAKEUP) {
|
|
place_entity(cfs_rq, se, 0);
|
|
enqueue_sleeper(cfs_rq, se);
|
|
}
|
|
|
|
update_stats_enqueue(cfs_rq, se);
|
|
check_spread(cfs_rq, se);
|
|
if (se != cfs_rq->curr)
|
|
__enqueue_entity(cfs_rq, se);
|
|
se->on_rq = 1;
|
|
|
|
if (cfs_rq->nr_running == 1) {
|
|
list_add_leaf_cfs_rq(cfs_rq);
|
|
check_enqueue_throttle(cfs_rq);
|
|
}
|
|
}
|
|
|
|
static void __clear_buddies_last(struct sched_entity *se)
|
|
{
|
|
for_each_sched_entity(se) {
|
|
struct cfs_rq *cfs_rq = cfs_rq_of(se);
|
|
if (cfs_rq->last == se)
|
|
cfs_rq->last = NULL;
|
|
else
|
|
break;
|
|
}
|
|
}
|
|
|
|
static void __clear_buddies_next(struct sched_entity *se)
|
|
{
|
|
for_each_sched_entity(se) {
|
|
struct cfs_rq *cfs_rq = cfs_rq_of(se);
|
|
if (cfs_rq->next == se)
|
|
cfs_rq->next = NULL;
|
|
else
|
|
break;
|
|
}
|
|
}
|
|
|
|
static void __clear_buddies_skip(struct sched_entity *se)
|
|
{
|
|
for_each_sched_entity(se) {
|
|
struct cfs_rq *cfs_rq = cfs_rq_of(se);
|
|
if (cfs_rq->skip == se)
|
|
cfs_rq->skip = NULL;
|
|
else
|
|
break;
|
|
}
|
|
}
|
|
|
|
static void clear_buddies(struct cfs_rq *cfs_rq, struct sched_entity *se)
|
|
{
|
|
if (cfs_rq->last == se)
|
|
__clear_buddies_last(se);
|
|
|
|
if (cfs_rq->next == se)
|
|
__clear_buddies_next(se);
|
|
|
|
if (cfs_rq->skip == se)
|
|
__clear_buddies_skip(se);
|
|
}
|
|
|
|
static __always_inline void return_cfs_rq_runtime(struct cfs_rq *cfs_rq);
|
|
|
|
static void
|
|
dequeue_entity(struct cfs_rq *cfs_rq, struct sched_entity *se, int flags)
|
|
{
|
|
/*
|
|
* Update run-time statistics of the 'current'.
|
|
*/
|
|
update_curr(cfs_rq);
|
|
dequeue_entity_load_avg(cfs_rq, se, flags & DEQUEUE_SLEEP);
|
|
|
|
update_stats_dequeue(cfs_rq, se);
|
|
if (flags & DEQUEUE_SLEEP) {
|
|
#ifdef CONFIG_SCHEDSTATS
|
|
if (entity_is_task(se)) {
|
|
struct task_struct *tsk = task_of(se);
|
|
|
|
if (tsk->state & TASK_INTERRUPTIBLE)
|
|
se->statistics.sleep_start = rq_of(cfs_rq)->clock;
|
|
if (tsk->state & TASK_UNINTERRUPTIBLE)
|
|
se->statistics.block_start = rq_of(cfs_rq)->clock;
|
|
}
|
|
#endif
|
|
}
|
|
|
|
clear_buddies(cfs_rq, se);
|
|
|
|
if (se != cfs_rq->curr)
|
|
__dequeue_entity(cfs_rq, se);
|
|
se->on_rq = 0;
|
|
account_entity_dequeue(cfs_rq, se);
|
|
|
|
/*
|
|
* Normalize the entity after updating the min_vruntime because the
|
|
* update can refer to the ->curr item and we need to reflect this
|
|
* movement in our normalized position.
|
|
*/
|
|
if (!(flags & DEQUEUE_SLEEP))
|
|
se->vruntime -= cfs_rq->min_vruntime;
|
|
|
|
/* return excess runtime on last dequeue */
|
|
return_cfs_rq_runtime(cfs_rq);
|
|
|
|
update_min_vruntime(cfs_rq);
|
|
update_cfs_shares(cfs_rq);
|
|
}
|
|
|
|
/*
|
|
* Preempt the current task with a newly woken task if needed:
|
|
*/
|
|
static void
|
|
check_preempt_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr)
|
|
{
|
|
unsigned long ideal_runtime, delta_exec;
|
|
struct sched_entity *se;
|
|
s64 delta;
|
|
|
|
ideal_runtime = sched_slice(cfs_rq, curr);
|
|
delta_exec = curr->sum_exec_runtime - curr->prev_sum_exec_runtime;
|
|
if (delta_exec > ideal_runtime) {
|
|
resched_task(rq_of(cfs_rq)->curr);
|
|
/*
|
|
* The current task ran long enough, ensure it doesn't get
|
|
* re-elected due to buddy favours.
|
|
*/
|
|
clear_buddies(cfs_rq, curr);
|
|
return;
|
|
}
|
|
|
|
/*
|
|
* Ensure that a task that missed wakeup preemption by a
|
|
* narrow margin doesn't have to wait for a full slice.
|
|
* This also mitigates buddy induced latencies under load.
|
|
*/
|
|
if (delta_exec < sysctl_sched_min_granularity)
|
|
return;
|
|
|
|
se = __pick_first_entity(cfs_rq);
|
|
delta = curr->vruntime - se->vruntime;
|
|
|
|
if (delta < 0)
|
|
return;
|
|
|
|
if (delta > ideal_runtime)
|
|
resched_task(rq_of(cfs_rq)->curr);
|
|
}
|
|
|
|
static void
|
|
set_next_entity(struct cfs_rq *cfs_rq, struct sched_entity *se)
|
|
{
|
|
/* 'current' is not kept within the tree. */
|
|
if (se->on_rq) {
|
|
/*
|
|
* Any task has to be enqueued before it get to execute on
|
|
* a CPU. So account for the time it spent waiting on the
|
|
* runqueue.
|
|
*/
|
|
update_stats_wait_end(cfs_rq, se);
|
|
__dequeue_entity(cfs_rq, se);
|
|
}
|
|
|
|
update_stats_curr_start(cfs_rq, se);
|
|
cfs_rq->curr = se;
|
|
#ifdef CONFIG_SCHEDSTATS
|
|
/*
|
|
* Track our maximum slice length, if the CPU's load is at
|
|
* least twice that of our own weight (i.e. dont track it
|
|
* when there are only lesser-weight tasks around):
|
|
*/
|
|
if (rq_of(cfs_rq)->load.weight >= 2*se->load.weight) {
|
|
se->statistics.slice_max = max(se->statistics.slice_max,
|
|
se->sum_exec_runtime - se->prev_sum_exec_runtime);
|
|
}
|
|
#endif
|
|
se->prev_sum_exec_runtime = se->sum_exec_runtime;
|
|
}
|
|
|
|
static int
|
|
wakeup_preempt_entity(struct sched_entity *curr, struct sched_entity *se);
|
|
|
|
/*
|
|
* Pick the next process, keeping these things in mind, in this order:
|
|
* 1) keep things fair between processes/task groups
|
|
* 2) pick the "next" process, since someone really wants that to run
|
|
* 3) pick the "last" process, for cache locality
|
|
* 4) do not run the "skip" process, if something else is available
|
|
*/
|
|
static struct sched_entity *pick_next_entity(struct cfs_rq *cfs_rq)
|
|
{
|
|
struct sched_entity *se = __pick_first_entity(cfs_rq);
|
|
struct sched_entity *left = se;
|
|
|
|
/*
|
|
* Avoid running the skip buddy, if running something else can
|
|
* be done without getting too unfair.
|
|
*/
|
|
if (cfs_rq->skip == se) {
|
|
struct sched_entity *second = __pick_next_entity(se);
|
|
if (second && wakeup_preempt_entity(second, left) < 1)
|
|
se = second;
|
|
}
|
|
|
|
/*
|
|
* Prefer last buddy, try to return the CPU to a preempted task.
|
|
*/
|
|
if (cfs_rq->last && wakeup_preempt_entity(cfs_rq->last, left) < 1)
|
|
se = cfs_rq->last;
|
|
|
|
/*
|
|
* Someone really wants this to run. If it's not unfair, run it.
|
|
*/
|
|
if (cfs_rq->next && wakeup_preempt_entity(cfs_rq->next, left) < 1)
|
|
se = cfs_rq->next;
|
|
|
|
clear_buddies(cfs_rq, se);
|
|
|
|
return se;
|
|
}
|
|
|
|
static void check_cfs_rq_runtime(struct cfs_rq *cfs_rq);
|
|
|
|
static void put_prev_entity(struct cfs_rq *cfs_rq, struct sched_entity *prev)
|
|
{
|
|
/*
|
|
* If still on the runqueue then deactivate_task()
|
|
* was not called and update_curr() has to be done:
|
|
*/
|
|
if (prev->on_rq)
|
|
update_curr(cfs_rq);
|
|
|
|
/* throttle cfs_rqs exceeding runtime */
|
|
check_cfs_rq_runtime(cfs_rq);
|
|
|
|
check_spread(cfs_rq, prev);
|
|
if (prev->on_rq) {
|
|
update_stats_wait_start(cfs_rq, prev);
|
|
/* Put 'current' back into the tree. */
|
|
__enqueue_entity(cfs_rq, prev);
|
|
/* in !on_rq case, update occurred at dequeue */
|
|
update_entity_load_avg(prev, 1);
|
|
}
|
|
cfs_rq->curr = NULL;
|
|
}
|
|
|
|
static void
|
|
entity_tick(struct cfs_rq *cfs_rq, struct sched_entity *curr, int queued)
|
|
{
|
|
/*
|
|
* Update run-time statistics of the 'current'.
|
|
*/
|
|
update_curr(cfs_rq);
|
|
|
|
/*
|
|
* Ensure that runnable average is periodically updated.
|
|
*/
|
|
update_entity_load_avg(curr, 1);
|
|
update_cfs_rq_blocked_load(cfs_rq, 1);
|
|
|
|
#ifdef CONFIG_SCHED_HRTICK
|
|
/*
|
|
* queued ticks are scheduled to match the slice, so don't bother
|
|
* validating it and just reschedule.
|
|
*/
|
|
if (queued) {
|
|
resched_task(rq_of(cfs_rq)->curr);
|
|
return;
|
|
}
|
|
/*
|
|
* don't let the period tick interfere with the hrtick preemption
|
|
*/
|
|
if (!sched_feat(DOUBLE_TICK) &&
|
|
hrtimer_active(&rq_of(cfs_rq)->hrtick_timer))
|
|
return;
|
|
#endif
|
|
|
|
if (cfs_rq->nr_running > 1)
|
|
check_preempt_tick(cfs_rq, curr);
|
|
}
|
|
|
|
|
|
/**************************************************
|
|
* CFS bandwidth control machinery
|
|
*/
|
|
|
|
#ifdef CONFIG_CFS_BANDWIDTH
|
|
|
|
#ifdef HAVE_JUMP_LABEL
|
|
static struct static_key __cfs_bandwidth_used;
|
|
|
|
static inline bool cfs_bandwidth_used(void)
|
|
{
|
|
return static_key_false(&__cfs_bandwidth_used);
|
|
}
|
|
|
|
void account_cfs_bandwidth_used(int enabled, int was_enabled)
|
|
{
|
|
/* only need to count groups transitioning between enabled/!enabled */
|
|
if (enabled && !was_enabled)
|
|
static_key_slow_inc(&__cfs_bandwidth_used);
|
|
else if (!enabled && was_enabled)
|
|
static_key_slow_dec(&__cfs_bandwidth_used);
|
|
}
|
|
#else /* HAVE_JUMP_LABEL */
|
|
static bool cfs_bandwidth_used(void)
|
|
{
|
|
return true;
|
|
}
|
|
|
|
void account_cfs_bandwidth_used(int enabled, int was_enabled) {}
|
|
#endif /* HAVE_JUMP_LABEL */
|
|
|
|
/*
|
|
* default period for cfs group bandwidth.
|
|
* default: 0.1s, units: nanoseconds
|
|
*/
|
|
static inline u64 default_cfs_period(void)
|
|
{
|
|
return 100000000ULL;
|
|
}
|
|
|
|
static inline u64 sched_cfs_bandwidth_slice(void)
|
|
{
|
|
return (u64)sysctl_sched_cfs_bandwidth_slice * NSEC_PER_USEC;
|
|
}
|
|
|
|
/*
|
|
* Replenish runtime according to assigned quota and update expiration time.
|
|
* We use sched_clock_cpu directly instead of rq->clock to avoid adding
|
|
* additional synchronization around rq->lock.
|
|
*
|
|
* requires cfs_b->lock
|
|
*/
|
|
void __refill_cfs_bandwidth_runtime(struct cfs_bandwidth *cfs_b)
|
|
{
|
|
u64 now;
|
|
|
|
if (cfs_b->quota == RUNTIME_INF)
|
|
return;
|
|
|
|
now = sched_clock_cpu(smp_processor_id());
|
|
cfs_b->runtime = cfs_b->quota;
|
|
cfs_b->runtime_expires = now + ktime_to_ns(cfs_b->period);
|
|
}
|
|
|
|
static inline struct cfs_bandwidth *tg_cfs_bandwidth(struct task_group *tg)
|
|
{
|
|
return &tg->cfs_bandwidth;
|
|
}
|
|
|
|
/* rq->task_clock normalized against any time this cfs_rq has spent throttled */
|
|
static inline u64 cfs_rq_clock_task(struct cfs_rq *cfs_rq)
|
|
{
|
|
if (unlikely(cfs_rq->throttle_count))
|
|
return cfs_rq->throttled_clock_task;
|
|
|
|
return rq_of(cfs_rq)->clock_task - cfs_rq->throttled_clock_task_time;
|
|
}
|
|
|
|
/* returns 0 on failure to allocate runtime */
|
|
static int assign_cfs_rq_runtime(struct cfs_rq *cfs_rq)
|
|
{
|
|
struct task_group *tg = cfs_rq->tg;
|
|
struct cfs_bandwidth *cfs_b = tg_cfs_bandwidth(tg);
|
|
u64 amount = 0, min_amount, expires;
|
|
|
|
/* note: this is a positive sum as runtime_remaining <= 0 */
|
|
min_amount = sched_cfs_bandwidth_slice() - cfs_rq->runtime_remaining;
|
|
|
|
raw_spin_lock(&cfs_b->lock);
|
|
if (cfs_b->quota == RUNTIME_INF)
|
|
amount = min_amount;
|
|
else {
|
|
/*
|
|
* If the bandwidth pool has become inactive, then at least one
|
|
* period must have elapsed since the last consumption.
|
|
* Refresh the global state and ensure bandwidth timer becomes
|
|
* active.
|
|
*/
|
|
if (!cfs_b->timer_active) {
|
|
__refill_cfs_bandwidth_runtime(cfs_b);
|
|
__start_cfs_bandwidth(cfs_b);
|
|
}
|
|
|
|
if (cfs_b->runtime > 0) {
|
|
amount = min(cfs_b->runtime, min_amount);
|
|
cfs_b->runtime -= amount;
|
|
cfs_b->idle = 0;
|
|
}
|
|
}
|
|
expires = cfs_b->runtime_expires;
|
|
raw_spin_unlock(&cfs_b->lock);
|
|
|
|
cfs_rq->runtime_remaining += amount;
|
|
/*
|
|
* we may have advanced our local expiration to account for allowed
|
|
* spread between our sched_clock and the one on which runtime was
|
|
* issued.
|
|
*/
|
|
if ((s64)(expires - cfs_rq->runtime_expires) > 0)
|
|
cfs_rq->runtime_expires = expires;
|
|
|
|
return cfs_rq->runtime_remaining > 0;
|
|
}
|
|
|
|
/*
|
|
* Note: This depends on the synchronization provided by sched_clock and the
|
|
* fact that rq->clock snapshots this value.
|
|
*/
|
|
static void expire_cfs_rq_runtime(struct cfs_rq *cfs_rq)
|
|
{
|
|
struct cfs_bandwidth *cfs_b = tg_cfs_bandwidth(cfs_rq->tg);
|
|
struct rq *rq = rq_of(cfs_rq);
|
|
|
|
/* if the deadline is ahead of our clock, nothing to do */
|
|
if (likely((s64)(rq->clock - cfs_rq->runtime_expires) < 0))
|
|
return;
|
|
|
|
if (cfs_rq->runtime_remaining < 0)
|
|
return;
|
|
|
|
/*
|
|
* If the local deadline has passed we have to consider the
|
|
* possibility that our sched_clock is 'fast' and the global deadline
|
|
* has not truly expired.
|
|
*
|
|
* Fortunately we can check determine whether this the case by checking
|
|
* whether the global deadline has advanced.
|
|
*/
|
|
|
|
if ((s64)(cfs_rq->runtime_expires - cfs_b->runtime_expires) >= 0) {
|
|
/* extend local deadline, drift is bounded above by 2 ticks */
|
|
cfs_rq->runtime_expires += TICK_NSEC;
|
|
} else {
|
|
/* global deadline is ahead, expiration has passed */
|
|
cfs_rq->runtime_remaining = 0;
|
|
}
|
|
}
|
|
|
|
static void __account_cfs_rq_runtime(struct cfs_rq *cfs_rq,
|
|
unsigned long delta_exec)
|
|
{
|
|
/* dock delta_exec before expiring quota (as it could span periods) */
|
|
cfs_rq->runtime_remaining -= delta_exec;
|
|
expire_cfs_rq_runtime(cfs_rq);
|
|
|
|
if (likely(cfs_rq->runtime_remaining > 0))
|
|
return;
|
|
|
|
/*
|
|
* if we're unable to extend our runtime we resched so that the active
|
|
* hierarchy can be throttled
|
|
*/
|
|
if (!assign_cfs_rq_runtime(cfs_rq) && likely(cfs_rq->curr))
|
|
resched_task(rq_of(cfs_rq)->curr);
|
|
}
|
|
|
|
static __always_inline
|
|
void account_cfs_rq_runtime(struct cfs_rq *cfs_rq, unsigned long delta_exec)
|
|
{
|
|
if (!cfs_bandwidth_used() || !cfs_rq->runtime_enabled)
|
|
return;
|
|
|
|
__account_cfs_rq_runtime(cfs_rq, delta_exec);
|
|
}
|
|
|
|
static inline int cfs_rq_throttled(struct cfs_rq *cfs_rq)
|
|
{
|
|
return cfs_bandwidth_used() && cfs_rq->throttled;
|
|
}
|
|
|
|
/* check whether cfs_rq, or any parent, is throttled */
|
|
static inline int throttled_hierarchy(struct cfs_rq *cfs_rq)
|
|
{
|
|
return cfs_bandwidth_used() && cfs_rq->throttle_count;
|
|
}
|
|
|
|
/*
|
|
* Ensure that neither of the group entities corresponding to src_cpu or
|
|
* dest_cpu are members of a throttled hierarchy when performing group
|
|
* load-balance operations.
|
|
*/
|
|
static inline int throttled_lb_pair(struct task_group *tg,
|
|
int src_cpu, int dest_cpu)
|
|
{
|
|
struct cfs_rq *src_cfs_rq, *dest_cfs_rq;
|
|
|
|
src_cfs_rq = tg->cfs_rq[src_cpu];
|
|
dest_cfs_rq = tg->cfs_rq[dest_cpu];
|
|
|
|
return throttled_hierarchy(src_cfs_rq) ||
|
|
throttled_hierarchy(dest_cfs_rq);
|
|
}
|
|
|
|
/* updated child weight may affect parent so we have to do this bottom up */
|
|
static int tg_unthrottle_up(struct task_group *tg, void *data)
|
|
{
|
|
struct rq *rq = data;
|
|
struct cfs_rq *cfs_rq = tg->cfs_rq[cpu_of(rq)];
|
|
|
|
cfs_rq->throttle_count--;
|
|
#ifdef CONFIG_SMP
|
|
if (!cfs_rq->throttle_count) {
|
|
/* adjust cfs_rq_clock_task() */
|
|
cfs_rq->throttled_clock_task_time += rq->clock_task -
|
|
cfs_rq->throttled_clock_task;
|
|
}
|
|
#endif
|
|
|
|
return 0;
|
|
}
|
|
|
|
static int tg_throttle_down(struct task_group *tg, void *data)
|
|
{
|
|
struct rq *rq = data;
|
|
struct cfs_rq *cfs_rq = tg->cfs_rq[cpu_of(rq)];
|
|
|
|
/* group is entering throttled state, stop time */
|
|
if (!cfs_rq->throttle_count)
|
|
cfs_rq->throttled_clock_task = rq->clock_task;
|
|
cfs_rq->throttle_count++;
|
|
|
|
return 0;
|
|
}
|
|
|
|
static void throttle_cfs_rq(struct cfs_rq *cfs_rq)
|
|
{
|
|
struct rq *rq = rq_of(cfs_rq);
|
|
struct cfs_bandwidth *cfs_b = tg_cfs_bandwidth(cfs_rq->tg);
|
|
struct sched_entity *se;
|
|
long task_delta, dequeue = 1;
|
|
|
|
se = cfs_rq->tg->se[cpu_of(rq_of(cfs_rq))];
|
|
|
|
/* freeze hierarchy runnable averages while throttled */
|
|
rcu_read_lock();
|
|
walk_tg_tree_from(cfs_rq->tg, tg_throttle_down, tg_nop, (void *)rq);
|
|
rcu_read_unlock();
|
|
|
|
task_delta = cfs_rq->h_nr_running;
|
|
for_each_sched_entity(se) {
|
|
struct cfs_rq *qcfs_rq = cfs_rq_of(se);
|
|
/* throttled entity or throttle-on-deactivate */
|
|
if (!se->on_rq)
|
|
break;
|
|
|
|
if (dequeue)
|
|
dequeue_entity(qcfs_rq, se, DEQUEUE_SLEEP);
|
|
qcfs_rq->h_nr_running -= task_delta;
|
|
|
|
if (qcfs_rq->load.weight)
|
|
dequeue = 0;
|
|
}
|
|
|
|
if (!se)
|
|
rq->nr_running -= task_delta;
|
|
|
|
cfs_rq->throttled = 1;
|
|
cfs_rq->throttled_clock = rq->clock;
|
|
raw_spin_lock(&cfs_b->lock);
|
|
list_add_tail_rcu(&cfs_rq->throttled_list, &cfs_b->throttled_cfs_rq);
|
|
raw_spin_unlock(&cfs_b->lock);
|
|
}
|
|
|
|
void unthrottle_cfs_rq(struct cfs_rq *cfs_rq)
|
|
{
|
|
struct rq *rq = rq_of(cfs_rq);
|
|
struct cfs_bandwidth *cfs_b = tg_cfs_bandwidth(cfs_rq->tg);
|
|
struct sched_entity *se;
|
|
int enqueue = 1;
|
|
long task_delta;
|
|
|
|
se = cfs_rq->tg->se[cpu_of(rq_of(cfs_rq))];
|
|
|
|
cfs_rq->throttled = 0;
|
|
|
|
update_rq_clock(rq);
|
|
|
|
raw_spin_lock(&cfs_b->lock);
|
|
cfs_b->throttled_time += rq->clock - cfs_rq->throttled_clock;
|
|
list_del_rcu(&cfs_rq->throttled_list);
|
|
raw_spin_unlock(&cfs_b->lock);
|
|
|
|
/* update hierarchical throttle state */
|
|
walk_tg_tree_from(cfs_rq->tg, tg_nop, tg_unthrottle_up, (void *)rq);
|
|
|
|
if (!cfs_rq->load.weight)
|
|
return;
|
|
|
|
task_delta = cfs_rq->h_nr_running;
|
|
for_each_sched_entity(se) {
|
|
if (se->on_rq)
|
|
enqueue = 0;
|
|
|
|
cfs_rq = cfs_rq_of(se);
|
|
if (enqueue)
|
|
enqueue_entity(cfs_rq, se, ENQUEUE_WAKEUP);
|
|
cfs_rq->h_nr_running += task_delta;
|
|
|
|
if (cfs_rq_throttled(cfs_rq))
|
|
break;
|
|
}
|
|
|
|
if (!se)
|
|
rq->nr_running += task_delta;
|
|
|
|
/* determine whether we need to wake up potentially idle cpu */
|
|
if (rq->curr == rq->idle && rq->cfs.nr_running)
|
|
resched_task(rq->curr);
|
|
}
|
|
|
|
static u64 distribute_cfs_runtime(struct cfs_bandwidth *cfs_b,
|
|
u64 remaining, u64 expires)
|
|
{
|
|
struct cfs_rq *cfs_rq;
|
|
u64 runtime = remaining;
|
|
|
|
rcu_read_lock();
|
|
list_for_each_entry_rcu(cfs_rq, &cfs_b->throttled_cfs_rq,
|
|
throttled_list) {
|
|
struct rq *rq = rq_of(cfs_rq);
|
|
|
|
raw_spin_lock(&rq->lock);
|
|
if (!cfs_rq_throttled(cfs_rq))
|
|
goto next;
|
|
|
|
runtime = -cfs_rq->runtime_remaining + 1;
|
|
if (runtime > remaining)
|
|
runtime = remaining;
|
|
remaining -= runtime;
|
|
|
|
cfs_rq->runtime_remaining += runtime;
|
|
cfs_rq->runtime_expires = expires;
|
|
|
|
/* we check whether we're throttled above */
|
|
if (cfs_rq->runtime_remaining > 0)
|
|
unthrottle_cfs_rq(cfs_rq);
|
|
|
|
next:
|
|
raw_spin_unlock(&rq->lock);
|
|
|
|
if (!remaining)
|
|
break;
|
|
}
|
|
rcu_read_unlock();
|
|
|
|
return remaining;
|
|
}
|
|
|
|
/*
|
|
* Responsible for refilling a task_group's bandwidth and unthrottling its
|
|
* cfs_rqs as appropriate. If there has been no activity within the last
|
|
* period the timer is deactivated until scheduling resumes; cfs_b->idle is
|
|
* used to track this state.
|
|
*/
|
|
static int do_sched_cfs_period_timer(struct cfs_bandwidth *cfs_b, int overrun)
|
|
{
|
|
u64 runtime, runtime_expires;
|
|
int idle = 1, throttled;
|
|
|
|
raw_spin_lock(&cfs_b->lock);
|
|
/* no need to continue the timer with no bandwidth constraint */
|
|
if (cfs_b->quota == RUNTIME_INF)
|
|
goto out_unlock;
|
|
|
|
throttled = !list_empty(&cfs_b->throttled_cfs_rq);
|
|
/* idle depends on !throttled (for the case of a large deficit) */
|
|
idle = cfs_b->idle && !throttled;
|
|
cfs_b->nr_periods += overrun;
|
|
|
|
/* if we're going inactive then everything else can be deferred */
|
|
if (idle)
|
|
goto out_unlock;
|
|
|
|
__refill_cfs_bandwidth_runtime(cfs_b);
|
|
|
|
if (!throttled) {
|
|
/* mark as potentially idle for the upcoming period */
|
|
cfs_b->idle = 1;
|
|
goto out_unlock;
|
|
}
|
|
|
|
/* account preceding periods in which throttling occurred */
|
|
cfs_b->nr_throttled += overrun;
|
|
|
|
/*
|
|
* There are throttled entities so we must first use the new bandwidth
|
|
* to unthrottle them before making it generally available. This
|
|
* ensures that all existing debts will be paid before a new cfs_rq is
|
|
* allowed to run.
|
|
*/
|
|
runtime = cfs_b->runtime;
|
|
runtime_expires = cfs_b->runtime_expires;
|
|
cfs_b->runtime = 0;
|
|
|
|
/*
|
|
* This check is repeated as we are holding onto the new bandwidth
|
|
* while we unthrottle. This can potentially race with an unthrottled
|
|
* group trying to acquire new bandwidth from the global pool.
|
|
*/
|
|
while (throttled && runtime > 0) {
|
|
raw_spin_unlock(&cfs_b->lock);
|
|
/* we can't nest cfs_b->lock while distributing bandwidth */
|
|
runtime = distribute_cfs_runtime(cfs_b, runtime,
|
|
runtime_expires);
|
|
raw_spin_lock(&cfs_b->lock);
|
|
|
|
throttled = !list_empty(&cfs_b->throttled_cfs_rq);
|
|
}
|
|
|
|
/* return (any) remaining runtime */
|
|
cfs_b->runtime = runtime;
|
|
/*
|
|
* While we are ensured activity in the period following an
|
|
* unthrottle, this also covers the case in which the new bandwidth is
|
|
* insufficient to cover the existing bandwidth deficit. (Forcing the
|
|
* timer to remain active while there are any throttled entities.)
|
|
*/
|
|
cfs_b->idle = 0;
|
|
out_unlock:
|
|
if (idle)
|
|
cfs_b->timer_active = 0;
|
|
raw_spin_unlock(&cfs_b->lock);
|
|
|
|
return idle;
|
|
}
|
|
|
|
/* a cfs_rq won't donate quota below this amount */
|
|
static const u64 min_cfs_rq_runtime = 1 * NSEC_PER_MSEC;
|
|
/* minimum remaining period time to redistribute slack quota */
|
|
static const u64 min_bandwidth_expiration = 2 * NSEC_PER_MSEC;
|
|
/* how long we wait to gather additional slack before distributing */
|
|
static const u64 cfs_bandwidth_slack_period = 5 * NSEC_PER_MSEC;
|
|
|
|
/* are we near the end of the current quota period? */
|
|
static int runtime_refresh_within(struct cfs_bandwidth *cfs_b, u64 min_expire)
|
|
{
|
|
struct hrtimer *refresh_timer = &cfs_b->period_timer;
|
|
u64 remaining;
|
|
|
|
/* if the call-back is running a quota refresh is already occurring */
|
|
if (hrtimer_callback_running(refresh_timer))
|
|
return 1;
|
|
|
|
/* is a quota refresh about to occur? */
|
|
remaining = ktime_to_ns(hrtimer_expires_remaining(refresh_timer));
|
|
if (remaining < min_expire)
|
|
return 1;
|
|
|
|
return 0;
|
|
}
|
|
|
|
static void start_cfs_slack_bandwidth(struct cfs_bandwidth *cfs_b)
|
|
{
|
|
u64 min_left = cfs_bandwidth_slack_period + min_bandwidth_expiration;
|
|
|
|
/* if there's a quota refresh soon don't bother with slack */
|
|
if (runtime_refresh_within(cfs_b, min_left))
|
|
return;
|
|
|
|
start_bandwidth_timer(&cfs_b->slack_timer,
|
|
ns_to_ktime(cfs_bandwidth_slack_period));
|
|
}
|
|
|
|
/* we know any runtime found here is valid as update_curr() precedes return */
|
|
static void __return_cfs_rq_runtime(struct cfs_rq *cfs_rq)
|
|
{
|
|
struct cfs_bandwidth *cfs_b = tg_cfs_bandwidth(cfs_rq->tg);
|
|
s64 slack_runtime = cfs_rq->runtime_remaining - min_cfs_rq_runtime;
|
|
|
|
if (slack_runtime <= 0)
|
|
return;
|
|
|
|
raw_spin_lock(&cfs_b->lock);
|
|
if (cfs_b->quota != RUNTIME_INF &&
|
|
cfs_rq->runtime_expires == cfs_b->runtime_expires) {
|
|
cfs_b->runtime += slack_runtime;
|
|
|
|
/* we are under rq->lock, defer unthrottling using a timer */
|
|
if (cfs_b->runtime > sched_cfs_bandwidth_slice() &&
|
|
!list_empty(&cfs_b->throttled_cfs_rq))
|
|
start_cfs_slack_bandwidth(cfs_b);
|
|
}
|
|
raw_spin_unlock(&cfs_b->lock);
|
|
|
|
/* even if it's not valid for return we don't want to try again */
|
|
cfs_rq->runtime_remaining -= slack_runtime;
|
|
}
|
|
|
|
static __always_inline void return_cfs_rq_runtime(struct cfs_rq *cfs_rq)
|
|
{
|
|
if (!cfs_bandwidth_used())
|
|
return;
|
|
|
|
if (!cfs_rq->runtime_enabled || cfs_rq->nr_running)
|
|
return;
|
|
|
|
__return_cfs_rq_runtime(cfs_rq);
|
|
}
|
|
|
|
/*
|
|
* This is done with a timer (instead of inline with bandwidth return) since
|
|
* it's necessary to juggle rq->locks to unthrottle their respective cfs_rqs.
|
|
*/
|
|
static void do_sched_cfs_slack_timer(struct cfs_bandwidth *cfs_b)
|
|
{
|
|
u64 runtime = 0, slice = sched_cfs_bandwidth_slice();
|
|
u64 expires;
|
|
|
|
/* confirm we're still not at a refresh boundary */
|
|
if (runtime_refresh_within(cfs_b, min_bandwidth_expiration))
|
|
return;
|
|
|
|
raw_spin_lock(&cfs_b->lock);
|
|
if (cfs_b->quota != RUNTIME_INF && cfs_b->runtime > slice) {
|
|
runtime = cfs_b->runtime;
|
|
cfs_b->runtime = 0;
|
|
}
|
|
expires = cfs_b->runtime_expires;
|
|
raw_spin_unlock(&cfs_b->lock);
|
|
|
|
if (!runtime)
|
|
return;
|
|
|
|
runtime = distribute_cfs_runtime(cfs_b, runtime, expires);
|
|
|
|
raw_spin_lock(&cfs_b->lock);
|
|
if (expires == cfs_b->runtime_expires)
|
|
cfs_b->runtime = runtime;
|
|
raw_spin_unlock(&cfs_b->lock);
|
|
}
|
|
|
|
/*
|
|
* When a group wakes up we want to make sure that its quota is not already
|
|
* expired/exceeded, otherwise it may be allowed to steal additional ticks of
|
|
* runtime as update_curr() throttling can not not trigger until it's on-rq.
|
|
*/
|
|
static void check_enqueue_throttle(struct cfs_rq *cfs_rq)
|
|
{
|
|
if (!cfs_bandwidth_used())
|
|
return;
|
|
|
|
/* an active group must be handled by the update_curr()->put() path */
|
|
if (!cfs_rq->runtime_enabled || cfs_rq->curr)
|
|
return;
|
|
|
|
/* ensure the group is not already throttled */
|
|
if (cfs_rq_throttled(cfs_rq))
|
|
return;
|
|
|
|
/* update runtime allocation */
|
|
account_cfs_rq_runtime(cfs_rq, 0);
|
|
if (cfs_rq->runtime_remaining <= 0)
|
|
throttle_cfs_rq(cfs_rq);
|
|
}
|
|
|
|
/* conditionally throttle active cfs_rq's from put_prev_entity() */
|
|
static void check_cfs_rq_runtime(struct cfs_rq *cfs_rq)
|
|
{
|
|
if (!cfs_bandwidth_used())
|
|
return;
|
|
|
|
if (likely(!cfs_rq->runtime_enabled || cfs_rq->runtime_remaining > 0))
|
|
return;
|
|
|
|
/*
|
|
* it's possible for a throttled entity to be forced into a running
|
|
* state (e.g. set_curr_task), in this case we're finished.
|
|
*/
|
|
if (cfs_rq_throttled(cfs_rq))
|
|
return;
|
|
|
|
throttle_cfs_rq(cfs_rq);
|
|
}
|
|
|
|
static inline u64 default_cfs_period(void);
|
|
static int do_sched_cfs_period_timer(struct cfs_bandwidth *cfs_b, int overrun);
|
|
static void do_sched_cfs_slack_timer(struct cfs_bandwidth *cfs_b);
|
|
|
|
static enum hrtimer_restart sched_cfs_slack_timer(struct hrtimer *timer)
|
|
{
|
|
struct cfs_bandwidth *cfs_b =
|
|
container_of(timer, struct cfs_bandwidth, slack_timer);
|
|
do_sched_cfs_slack_timer(cfs_b);
|
|
|
|
return HRTIMER_NORESTART;
|
|
}
|
|
|
|
static enum hrtimer_restart sched_cfs_period_timer(struct hrtimer *timer)
|
|
{
|
|
struct cfs_bandwidth *cfs_b =
|
|
container_of(timer, struct cfs_bandwidth, period_timer);
|
|
ktime_t now;
|
|
int overrun;
|
|
int idle = 0;
|
|
|
|
for (;;) {
|
|
now = hrtimer_cb_get_time(timer);
|
|
overrun = hrtimer_forward(timer, now, cfs_b->period);
|
|
|
|
if (!overrun)
|
|
break;
|
|
|
|
idle = do_sched_cfs_period_timer(cfs_b, overrun);
|
|
}
|
|
|
|
return idle ? HRTIMER_NORESTART : HRTIMER_RESTART;
|
|
}
|
|
|
|
void init_cfs_bandwidth(struct cfs_bandwidth *cfs_b)
|
|
{
|
|
raw_spin_lock_init(&cfs_b->lock);
|
|
cfs_b->runtime = 0;
|
|
cfs_b->quota = RUNTIME_INF;
|
|
cfs_b->period = ns_to_ktime(default_cfs_period());
|
|
|
|
INIT_LIST_HEAD(&cfs_b->throttled_cfs_rq);
|
|
hrtimer_init(&cfs_b->period_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
|
|
cfs_b->period_timer.function = sched_cfs_period_timer;
|
|
hrtimer_init(&cfs_b->slack_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
|
|
cfs_b->slack_timer.function = sched_cfs_slack_timer;
|
|
}
|
|
|
|
static void init_cfs_rq_runtime(struct cfs_rq *cfs_rq)
|
|
{
|
|
cfs_rq->runtime_enabled = 0;
|
|
INIT_LIST_HEAD(&cfs_rq->throttled_list);
|
|
}
|
|
|
|
/* requires cfs_b->lock, may release to reprogram timer */
|
|
void __start_cfs_bandwidth(struct cfs_bandwidth *cfs_b)
|
|
{
|
|
/*
|
|
* The timer may be active because we're trying to set a new bandwidth
|
|
* period or because we're racing with the tear-down path
|
|
* (timer_active==0 becomes visible before the hrtimer call-back
|
|
* terminates). In either case we ensure that it's re-programmed
|
|
*/
|
|
while (unlikely(hrtimer_active(&cfs_b->period_timer))) {
|
|
raw_spin_unlock(&cfs_b->lock);
|
|
/* ensure cfs_b->lock is available while we wait */
|
|
hrtimer_cancel(&cfs_b->period_timer);
|
|
|
|
raw_spin_lock(&cfs_b->lock);
|
|
/* if someone else restarted the timer then we're done */
|
|
if (cfs_b->timer_active)
|
|
return;
|
|
}
|
|
|
|
cfs_b->timer_active = 1;
|
|
start_bandwidth_timer(&cfs_b->period_timer, cfs_b->period);
|
|
}
|
|
|
|
static void destroy_cfs_bandwidth(struct cfs_bandwidth *cfs_b)
|
|
{
|
|
hrtimer_cancel(&cfs_b->period_timer);
|
|
hrtimer_cancel(&cfs_b->slack_timer);
|
|
}
|
|
|
|
static void __maybe_unused unthrottle_offline_cfs_rqs(struct rq *rq)
|
|
{
|
|
struct cfs_rq *cfs_rq;
|
|
|
|
for_each_leaf_cfs_rq(rq, cfs_rq) {
|
|
struct cfs_bandwidth *cfs_b = tg_cfs_bandwidth(cfs_rq->tg);
|
|
|
|
if (!cfs_rq->runtime_enabled)
|
|
continue;
|
|
|
|
/*
|
|
* clock_task is not advancing so we just need to make sure
|
|
* there's some valid quota amount
|
|
*/
|
|
cfs_rq->runtime_remaining = cfs_b->quota;
|
|
if (cfs_rq_throttled(cfs_rq))
|
|
unthrottle_cfs_rq(cfs_rq);
|
|
}
|
|
}
|
|
|
|
#else /* CONFIG_CFS_BANDWIDTH */
|
|
static inline u64 cfs_rq_clock_task(struct cfs_rq *cfs_rq)
|
|
{
|
|
return rq_of(cfs_rq)->clock_task;
|
|
}
|
|
|
|
static void account_cfs_rq_runtime(struct cfs_rq *cfs_rq,
|
|
unsigned long delta_exec) {}
|
|
static void check_cfs_rq_runtime(struct cfs_rq *cfs_rq) {}
|
|
static void check_enqueue_throttle(struct cfs_rq *cfs_rq) {}
|
|
static __always_inline void return_cfs_rq_runtime(struct cfs_rq *cfs_rq) {}
|
|
|
|
static inline int cfs_rq_throttled(struct cfs_rq *cfs_rq)
|
|
{
|
|
return 0;
|
|
}
|
|
|
|
static inline int throttled_hierarchy(struct cfs_rq *cfs_rq)
|
|
{
|
|
return 0;
|
|
}
|
|
|
|
static inline int throttled_lb_pair(struct task_group *tg,
|
|
int src_cpu, int dest_cpu)
|
|
{
|
|
return 0;
|
|
}
|
|
|
|
void init_cfs_bandwidth(struct cfs_bandwidth *cfs_b) {}
|
|
|
|
#ifdef CONFIG_FAIR_GROUP_SCHED
|
|
static void init_cfs_rq_runtime(struct cfs_rq *cfs_rq) {}
|
|
#endif
|
|
|
|
static inline struct cfs_bandwidth *tg_cfs_bandwidth(struct task_group *tg)
|
|
{
|
|
return NULL;
|
|
}
|
|
static inline void destroy_cfs_bandwidth(struct cfs_bandwidth *cfs_b) {}
|
|
static inline void unthrottle_offline_cfs_rqs(struct rq *rq) {}
|
|
|
|
#endif /* CONFIG_CFS_BANDWIDTH */
|
|
|
|
/**************************************************
|
|
* CFS operations on tasks:
|
|
*/
|
|
|
|
#ifdef CONFIG_SCHED_HRTICK
|
|
static void hrtick_start_fair(struct rq *rq, struct task_struct *p)
|
|
{
|
|
struct sched_entity *se = &p->se;
|
|
struct cfs_rq *cfs_rq = cfs_rq_of(se);
|
|
|
|
WARN_ON(task_rq(p) != rq);
|
|
|
|
if (cfs_rq->nr_running > 1) {
|
|
u64 slice = sched_slice(cfs_rq, se);
|
|
u64 ran = se->sum_exec_runtime - se->prev_sum_exec_runtime;
|
|
s64 delta = slice - ran;
|
|
|
|
if (delta < 0) {
|
|
if (rq->curr == p)
|
|
resched_task(p);
|
|
return;
|
|
}
|
|
|
|
/*
|
|
* Don't schedule slices shorter than 10000ns, that just
|
|
* doesn't make sense. Rely on vruntime for fairness.
|
|
*/
|
|
if (rq->curr != p)
|
|
delta = max_t(s64, 10000LL, delta);
|
|
|
|
hrtick_start(rq, delta);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* called from enqueue/dequeue and updates the hrtick when the
|
|
* current task is from our class and nr_running is low enough
|
|
* to matter.
|
|
*/
|
|
static void hrtick_update(struct rq *rq)
|
|
{
|
|
struct task_struct *curr = rq->curr;
|
|
|
|
if (!hrtick_enabled(rq) || curr->sched_class != &fair_sched_class)
|
|
return;
|
|
|
|
if (cfs_rq_of(&curr->se)->nr_running < sched_nr_latency)
|
|
hrtick_start_fair(rq, curr);
|
|
}
|
|
#else /* !CONFIG_SCHED_HRTICK */
|
|
static inline void
|
|
hrtick_start_fair(struct rq *rq, struct task_struct *p)
|
|
{
|
|
}
|
|
|
|
static inline void hrtick_update(struct rq *rq)
|
|
{
|
|
}
|
|
#endif
|
|
|
|
/*
|
|
* The enqueue_task method is called before nr_running is
|
|
* increased. Here we update the fair scheduling stats and
|
|
* then put the task into the rbtree:
|
|
*/
|
|
static void
|
|
enqueue_task_fair(struct rq *rq, struct task_struct *p, int flags)
|
|
{
|
|
struct cfs_rq *cfs_rq;
|
|
struct sched_entity *se = &p->se;
|
|
|
|
for_each_sched_entity(se) {
|
|
if (se->on_rq)
|
|
break;
|
|
cfs_rq = cfs_rq_of(se);
|
|
enqueue_entity(cfs_rq, se, flags);
|
|
|
|
/*
|
|
* end evaluation on encountering a throttled cfs_rq
|
|
*
|
|
* note: in the case of encountering a throttled cfs_rq we will
|
|
* post the final h_nr_running increment below.
|
|
*/
|
|
if (cfs_rq_throttled(cfs_rq))
|
|
break;
|
|
cfs_rq->h_nr_running++;
|
|
|
|
flags = ENQUEUE_WAKEUP;
|
|
}
|
|
|
|
for_each_sched_entity(se) {
|
|
cfs_rq = cfs_rq_of(se);
|
|
cfs_rq->h_nr_running++;
|
|
|
|
if (cfs_rq_throttled(cfs_rq))
|
|
break;
|
|
|
|
update_cfs_shares(cfs_rq);
|
|
update_entity_load_avg(se, 1);
|
|
}
|
|
|
|
if (!se) {
|
|
update_rq_runnable_avg(rq, rq->nr_running);
|
|
inc_nr_running(rq);
|
|
}
|
|
hrtick_update(rq);
|
|
}
|
|
|
|
static void set_next_buddy(struct sched_entity *se);
|
|
|
|
/*
|
|
* The dequeue_task method is called before nr_running is
|
|
* decreased. We remove the task from the rbtree and
|
|
* update the fair scheduling stats:
|
|
*/
|
|
static void dequeue_task_fair(struct rq *rq, struct task_struct *p, int flags)
|
|
{
|
|
struct cfs_rq *cfs_rq;
|
|
struct sched_entity *se = &p->se;
|
|
int task_sleep = flags & DEQUEUE_SLEEP;
|
|
|
|
for_each_sched_entity(se) {
|
|
cfs_rq = cfs_rq_of(se);
|
|
dequeue_entity(cfs_rq, se, flags);
|
|
|
|
/*
|
|
* end evaluation on encountering a throttled cfs_rq
|
|
*
|
|
* note: in the case of encountering a throttled cfs_rq we will
|
|
* post the final h_nr_running decrement below.
|
|
*/
|
|
if (cfs_rq_throttled(cfs_rq))
|
|
break;
|
|
cfs_rq->h_nr_running--;
|
|
|
|
/* Don't dequeue parent if it has other entities besides us */
|
|
if (cfs_rq->load.weight) {
|
|
/*
|
|
* Bias pick_next to pick a task from this cfs_rq, as
|
|
* p is sleeping when it is within its sched_slice.
|
|
*/
|
|
if (task_sleep && parent_entity(se))
|
|
set_next_buddy(parent_entity(se));
|
|
|
|
/* avoid re-evaluating load for this entity */
|
|
se = parent_entity(se);
|
|
break;
|
|
}
|
|
flags |= DEQUEUE_SLEEP;
|
|
}
|
|
|
|
for_each_sched_entity(se) {
|
|
cfs_rq = cfs_rq_of(se);
|
|
cfs_rq->h_nr_running--;
|
|
|
|
if (cfs_rq_throttled(cfs_rq))
|
|
break;
|
|
|
|
update_cfs_shares(cfs_rq);
|
|
update_entity_load_avg(se, 1);
|
|
}
|
|
|
|
if (!se) {
|
|
dec_nr_running(rq);
|
|
update_rq_runnable_avg(rq, 1);
|
|
}
|
|
hrtick_update(rq);
|
|
}
|
|
|
|
#ifdef CONFIG_SMP
|
|
/* Used instead of source_load when we know the type == 0 */
|
|
static unsigned long weighted_cpuload(const int cpu)
|
|
{
|
|
return cpu_rq(cpu)->load.weight;
|
|
}
|
|
|
|
/*
|
|
* Return a low guess at the load of a migration-source cpu weighted
|
|
* according to the scheduling class and "nice" value.
|
|
*
|
|
* We want to under-estimate the load of migration sources, to
|
|
* balance conservatively.
|
|
*/
|
|
static unsigned long source_load(int cpu, int type)
|
|
{
|
|
struct rq *rq = cpu_rq(cpu);
|
|
unsigned long total = weighted_cpuload(cpu);
|
|
|
|
if (type == 0 || !sched_feat(LB_BIAS))
|
|
return total;
|
|
|
|
return min(rq->cpu_load[type-1], total);
|
|
}
|
|
|
|
/*
|
|
* Return a high guess at the load of a migration-target cpu weighted
|
|
* according to the scheduling class and "nice" value.
|
|
*/
|
|
static unsigned long target_load(int cpu, int type)
|
|
{
|
|
struct rq *rq = cpu_rq(cpu);
|
|
unsigned long total = weighted_cpuload(cpu);
|
|
|
|
if (type == 0 || !sched_feat(LB_BIAS))
|
|
return total;
|
|
|
|
return max(rq->cpu_load[type-1], total);
|
|
}
|
|
|
|
static unsigned long power_of(int cpu)
|
|
{
|
|
return cpu_rq(cpu)->cpu_power;
|
|
}
|
|
|
|
static unsigned long cpu_avg_load_per_task(int cpu)
|
|
{
|
|
struct rq *rq = cpu_rq(cpu);
|
|
unsigned long nr_running = ACCESS_ONCE(rq->nr_running);
|
|
|
|
if (nr_running)
|
|
return rq->load.weight / nr_running;
|
|
|
|
return 0;
|
|
}
|
|
|
|
|
|
static void task_waking_fair(struct task_struct *p)
|
|
{
|
|
struct sched_entity *se = &p->se;
|
|
struct cfs_rq *cfs_rq = cfs_rq_of(se);
|
|
u64 min_vruntime;
|
|
|
|
#ifndef CONFIG_64BIT
|
|
u64 min_vruntime_copy;
|
|
|
|
do {
|
|
min_vruntime_copy = cfs_rq->min_vruntime_copy;
|
|
smp_rmb();
|
|
min_vruntime = cfs_rq->min_vruntime;
|
|
} while (min_vruntime != min_vruntime_copy);
|
|
#else
|
|
min_vruntime = cfs_rq->min_vruntime;
|
|
#endif
|
|
|
|
se->vruntime -= min_vruntime;
|
|
}
|
|
|
|
#ifdef CONFIG_FAIR_GROUP_SCHED
|
|
/*
|
|
* effective_load() calculates the load change as seen from the root_task_group
|
|
*
|
|
* Adding load to a group doesn't make a group heavier, but can cause movement
|
|
* of group shares between cpus. Assuming the shares were perfectly aligned one
|
|
* can calculate the shift in shares.
|
|
*
|
|
* Calculate the effective load difference if @wl is added (subtracted) to @tg
|
|
* on this @cpu and results in a total addition (subtraction) of @wg to the
|
|
* total group weight.
|
|
*
|
|
* Given a runqueue weight distribution (rw_i) we can compute a shares
|
|
* distribution (s_i) using:
|
|
*
|
|
* s_i = rw_i / \Sum rw_j (1)
|
|
*
|
|
* Suppose we have 4 CPUs and our @tg is a direct child of the root group and
|
|
* has 7 equal weight tasks, distributed as below (rw_i), with the resulting
|
|
* shares distribution (s_i):
|
|
*
|
|
* rw_i = { 2, 4, 1, 0 }
|
|
* s_i = { 2/7, 4/7, 1/7, 0 }
|
|
*
|
|
* As per wake_affine() we're interested in the load of two CPUs (the CPU the
|
|
* task used to run on and the CPU the waker is running on), we need to
|
|
* compute the effect of waking a task on either CPU and, in case of a sync
|
|
* wakeup, compute the effect of the current task going to sleep.
|
|
*
|
|
* So for a change of @wl to the local @cpu with an overall group weight change
|
|
* of @wl we can compute the new shares distribution (s'_i) using:
|
|
*
|
|
* s'_i = (rw_i + @wl) / (@wg + \Sum rw_j) (2)
|
|
*
|
|
* Suppose we're interested in CPUs 0 and 1, and want to compute the load
|
|
* differences in waking a task to CPU 0. The additional task changes the
|
|
* weight and shares distributions like:
|
|
*
|
|
* rw'_i = { 3, 4, 1, 0 }
|
|
* s'_i = { 3/8, 4/8, 1/8, 0 }
|
|
*
|
|
* We can then compute the difference in effective weight by using:
|
|
*
|
|
* dw_i = S * (s'_i - s_i) (3)
|
|
*
|
|
* Where 'S' is the group weight as seen by its parent.
|
|
*
|
|
* Therefore the effective change in loads on CPU 0 would be 5/56 (3/8 - 2/7)
|
|
* times the weight of the group. The effect on CPU 1 would be -4/56 (4/8 -
|
|
* 4/7) times the weight of the group.
|
|
*/
|
|
static long effective_load(struct task_group *tg, int cpu, long wl, long wg)
|
|
{
|
|
struct sched_entity *se = tg->se[cpu];
|
|
|
|
if (!tg->parent) /* the trivial, non-cgroup case */
|
|
return wl;
|
|
|
|
for_each_sched_entity(se) {
|
|
long w, W;
|
|
|
|
tg = se->my_q->tg;
|
|
|
|
/*
|
|
* W = @wg + \Sum rw_j
|
|
*/
|
|
W = wg + calc_tg_weight(tg, se->my_q);
|
|
|
|
/*
|
|
* w = rw_i + @wl
|
|
*/
|
|
w = se->my_q->load.weight + wl;
|
|
|
|
/*
|
|
* wl = S * s'_i; see (2)
|
|
*/
|
|
if (W > 0 && w < W)
|
|
wl = (w * tg->shares) / W;
|
|
else
|
|
wl = tg->shares;
|
|
|
|
/*
|
|
* Per the above, wl is the new se->load.weight value; since
|
|
* those are clipped to [MIN_SHARES, ...) do so now. See
|
|
* calc_cfs_shares().
|
|
*/
|
|
if (wl < MIN_SHARES)
|
|
wl = MIN_SHARES;
|
|
|
|
/*
|
|
* wl = dw_i = S * (s'_i - s_i); see (3)
|
|
*/
|
|
wl -= se->load.weight;
|
|
|
|
/*
|
|
* Recursively apply this logic to all parent groups to compute
|
|
* the final effective load change on the root group. Since
|
|
* only the @tg group gets extra weight, all parent groups can
|
|
* only redistribute existing shares. @wl is the shift in shares
|
|
* resulting from this level per the above.
|
|
*/
|
|
wg = 0;
|
|
}
|
|
|
|
return wl;
|
|
}
|
|
#else
|
|
|
|
static inline unsigned long effective_load(struct task_group *tg, int cpu,
|
|
unsigned long wl, unsigned long wg)
|
|
{
|
|
return wl;
|
|
}
|
|
|
|
#endif
|
|
|
|
static int wake_affine(struct sched_domain *sd, struct task_struct *p, int sync)
|
|
{
|
|
s64 this_load, load;
|
|
int idx, this_cpu, prev_cpu;
|
|
unsigned long tl_per_task;
|
|
struct task_group *tg;
|
|
unsigned long weight;
|
|
int balanced;
|
|
|
|
idx = sd->wake_idx;
|
|
this_cpu = smp_processor_id();
|
|
prev_cpu = task_cpu(p);
|
|
load = source_load(prev_cpu, idx);
|
|
this_load = target_load(this_cpu, idx);
|
|
|
|
/*
|
|
* If sync wakeup then subtract the (maximum possible)
|
|
* effect of the currently running task from the load
|
|
* of the current CPU:
|
|
*/
|
|
if (sync) {
|
|
tg = task_group(current);
|
|
weight = current->se.load.weight;
|
|
|
|
this_load += effective_load(tg, this_cpu, -weight, -weight);
|
|
load += effective_load(tg, prev_cpu, 0, -weight);
|
|
}
|
|
|
|
tg = task_group(p);
|
|
weight = p->se.load.weight;
|
|
|
|
/*
|
|
* In low-load situations, where prev_cpu is idle and this_cpu is idle
|
|
* due to the sync cause above having dropped this_load to 0, we'll
|
|
* always have an imbalance, but there's really nothing you can do
|
|
* about that, so that's good too.
|
|
*
|
|
* Otherwise check if either cpus are near enough in load to allow this
|
|
* task to be woken on this_cpu.
|
|
*/
|
|
if (this_load > 0) {
|
|
s64 this_eff_load, prev_eff_load;
|
|
|
|
this_eff_load = 100;
|
|
this_eff_load *= power_of(prev_cpu);
|
|
this_eff_load *= this_load +
|
|
effective_load(tg, this_cpu, weight, weight);
|
|
|
|
prev_eff_load = 100 + (sd->imbalance_pct - 100) / 2;
|
|
prev_eff_load *= power_of(this_cpu);
|
|
prev_eff_load *= load + effective_load(tg, prev_cpu, 0, weight);
|
|
|
|
balanced = this_eff_load <= prev_eff_load;
|
|
} else
|
|
balanced = true;
|
|
|
|
/*
|
|
* If the currently running task will sleep within
|
|
* a reasonable amount of time then attract this newly
|
|
* woken task:
|
|
*/
|
|
if (sync && balanced)
|
|
return 1;
|
|
|
|
schedstat_inc(p, se.statistics.nr_wakeups_affine_attempts);
|
|
tl_per_task = cpu_avg_load_per_task(this_cpu);
|
|
|
|
if (balanced ||
|
|
(this_load <= load &&
|
|
this_load + target_load(prev_cpu, idx) <= tl_per_task)) {
|
|
/*
|
|
* This domain has SD_WAKE_AFFINE and
|
|
* p is cache cold in this domain, and
|
|
* there is no bad imbalance.
|
|
*/
|
|
schedstat_inc(sd, ttwu_move_affine);
|
|
schedstat_inc(p, se.statistics.nr_wakeups_affine);
|
|
|
|
return 1;
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* find_idlest_group finds and returns the least busy CPU group within the
|
|
* domain.
|
|
*/
|
|
static struct sched_group *
|
|
find_idlest_group(struct sched_domain *sd, struct task_struct *p,
|
|
int this_cpu, int load_idx)
|
|
{
|
|
struct sched_group *idlest = NULL, *group = sd->groups;
|
|
unsigned long min_load = ULONG_MAX, this_load = 0;
|
|
int imbalance = 100 + (sd->imbalance_pct-100)/2;
|
|
|
|
do {
|
|
unsigned long load, avg_load;
|
|
int local_group;
|
|
int i;
|
|
|
|
/* Skip over this group if it has no CPUs allowed */
|
|
if (!cpumask_intersects(sched_group_cpus(group),
|
|
tsk_cpus_allowed(p)))
|
|
continue;
|
|
|
|
local_group = cpumask_test_cpu(this_cpu,
|
|
sched_group_cpus(group));
|
|
|
|
/* Tally up the load of all CPUs in the group */
|
|
avg_load = 0;
|
|
|
|
for_each_cpu(i, sched_group_cpus(group)) {
|
|
/* Bias balancing toward cpus of our domain */
|
|
if (local_group)
|
|
load = source_load(i, load_idx);
|
|
else
|
|
load = target_load(i, load_idx);
|
|
|
|
avg_load += load;
|
|
}
|
|
|
|
/* Adjust by relative CPU power of the group */
|
|
avg_load = (avg_load * SCHED_POWER_SCALE) / group->sgp->power;
|
|
|
|
if (local_group) {
|
|
this_load = avg_load;
|
|
} else if (avg_load < min_load) {
|
|
min_load = avg_load;
|
|
idlest = group;
|
|
}
|
|
} while (group = group->next, group != sd->groups);
|
|
|
|
if (!idlest || 100*this_load < imbalance*min_load)
|
|
return NULL;
|
|
return idlest;
|
|
}
|
|
|
|
/*
|
|
* find_idlest_cpu - find the idlest cpu among the cpus in group.
|
|
*/
|
|
static int
|
|
find_idlest_cpu(struct sched_group *group, struct task_struct *p, int this_cpu)
|
|
{
|
|
unsigned long load, min_load = ULONG_MAX;
|
|
int idlest = -1;
|
|
int i;
|
|
|
|
/* Traverse only the allowed CPUs */
|
|
for_each_cpu_and(i, sched_group_cpus(group), tsk_cpus_allowed(p)) {
|
|
load = weighted_cpuload(i);
|
|
|
|
if (load < min_load || (load == min_load && i == this_cpu)) {
|
|
min_load = load;
|
|
idlest = i;
|
|
}
|
|
}
|
|
|
|
return idlest;
|
|
}
|
|
|
|
/*
|
|
* Try and locate an idle CPU in the sched_domain.
|
|
*/
|
|
static int select_idle_sibling(struct task_struct *p, int target)
|
|
{
|
|
struct sched_domain *sd;
|
|
struct sched_group *sg;
|
|
int i = task_cpu(p);
|
|
|
|
if (idle_cpu(target))
|
|
return target;
|
|
|
|
/*
|
|
* If the prevous cpu is cache affine and idle, don't be stupid.
|
|
*/
|
|
if (i != target && cpus_share_cache(i, target) && idle_cpu(i))
|
|
return i;
|
|
|
|
/*
|
|
* Otherwise, iterate the domains and find an elegible idle cpu.
|
|
*/
|
|
sd = rcu_dereference(per_cpu(sd_llc, target));
|
|
for_each_lower_domain(sd) {
|
|
sg = sd->groups;
|
|
do {
|
|
if (!cpumask_intersects(sched_group_cpus(sg),
|
|
tsk_cpus_allowed(p)))
|
|
goto next;
|
|
|
|
for_each_cpu(i, sched_group_cpus(sg)) {
|
|
if (i == target || !idle_cpu(i))
|
|
goto next;
|
|
}
|
|
|
|
target = cpumask_first_and(sched_group_cpus(sg),
|
|
tsk_cpus_allowed(p));
|
|
goto done;
|
|
next:
|
|
sg = sg->next;
|
|
} while (sg != sd->groups);
|
|
}
|
|
done:
|
|
return target;
|
|
}
|
|
|
|
/*
|
|
* sched_balance_self: balance the current task (running on cpu) in domains
|
|
* that have the 'flag' flag set. In practice, this is SD_BALANCE_FORK and
|
|
* SD_BALANCE_EXEC.
|
|
*
|
|
* Balance, ie. select the least loaded group.
|
|
*
|
|
* Returns the target CPU number, or the same CPU if no balancing is needed.
|
|
*
|
|
* preempt must be disabled.
|
|
*/
|
|
static int
|
|
select_task_rq_fair(struct task_struct *p, int sd_flag, int wake_flags)
|
|
{
|
|
struct sched_domain *tmp, *affine_sd = NULL, *sd = NULL;
|
|
int cpu = smp_processor_id();
|
|
int prev_cpu = task_cpu(p);
|
|
int new_cpu = cpu;
|
|
int want_affine = 0;
|
|
int sync = wake_flags & WF_SYNC;
|
|
|
|
if (p->nr_cpus_allowed == 1)
|
|
return prev_cpu;
|
|
|
|
if (sd_flag & SD_BALANCE_WAKE) {
|
|
if (cpumask_test_cpu(cpu, tsk_cpus_allowed(p)))
|
|
want_affine = 1;
|
|
new_cpu = prev_cpu;
|
|
}
|
|
|
|
rcu_read_lock();
|
|
for_each_domain(cpu, tmp) {
|
|
if (!(tmp->flags & SD_LOAD_BALANCE))
|
|
continue;
|
|
|
|
/*
|
|
* If both cpu and prev_cpu are part of this domain,
|
|
* cpu is a valid SD_WAKE_AFFINE target.
|
|
*/
|
|
if (want_affine && (tmp->flags & SD_WAKE_AFFINE) &&
|
|
cpumask_test_cpu(prev_cpu, sched_domain_span(tmp))) {
|
|
affine_sd = tmp;
|
|
break;
|
|
}
|
|
|
|
if (tmp->flags & sd_flag)
|
|
sd = tmp;
|
|
}
|
|
|
|
if (affine_sd) {
|
|
if (cpu != prev_cpu && wake_affine(affine_sd, p, sync))
|
|
prev_cpu = cpu;
|
|
|
|
new_cpu = select_idle_sibling(p, prev_cpu);
|
|
goto unlock;
|
|
}
|
|
|
|
while (sd) {
|
|
int load_idx = sd->forkexec_idx;
|
|
struct sched_group *group;
|
|
int weight;
|
|
|
|
if (!(sd->flags & sd_flag)) {
|
|
sd = sd->child;
|
|
continue;
|
|
}
|
|
|
|
if (sd_flag & SD_BALANCE_WAKE)
|
|
load_idx = sd->wake_idx;
|
|
|
|
group = find_idlest_group(sd, p, cpu, load_idx);
|
|
if (!group) {
|
|
sd = sd->child;
|
|
continue;
|
|
}
|
|
|
|
new_cpu = find_idlest_cpu(group, p, cpu);
|
|
if (new_cpu == -1 || new_cpu == cpu) {
|
|
/* Now try balancing at a lower domain level of cpu */
|
|
sd = sd->child;
|
|
continue;
|
|
}
|
|
|
|
/* Now try balancing at a lower domain level of new_cpu */
|
|
cpu = new_cpu;
|
|
weight = sd->span_weight;
|
|
sd = NULL;
|
|
for_each_domain(cpu, tmp) {
|
|
if (weight <= tmp->span_weight)
|
|
break;
|
|
if (tmp->flags & sd_flag)
|
|
sd = tmp;
|
|
}
|
|
/* while loop will break here if sd == NULL */
|
|
}
|
|
unlock:
|
|
rcu_read_unlock();
|
|
|
|
return new_cpu;
|
|
}
|
|
|
|
/*
|
|
* Load-tracking only depends on SMP, FAIR_GROUP_SCHED dependency below may be
|
|
* removed when useful for applications beyond shares distribution (e.g.
|
|
* load-balance).
|
|
*/
|
|
#ifdef CONFIG_FAIR_GROUP_SCHED
|
|
/*
|
|
* Called immediately before a task is migrated to a new cpu; task_cpu(p) and
|
|
* cfs_rq_of(p) references at time of call are still valid and identify the
|
|
* previous cpu. However, the caller only guarantees p->pi_lock is held; no
|
|
* other assumptions, including the state of rq->lock, should be made.
|
|
*/
|
|
static void
|
|
migrate_task_rq_fair(struct task_struct *p, int next_cpu)
|
|
{
|
|
struct sched_entity *se = &p->se;
|
|
struct cfs_rq *cfs_rq = cfs_rq_of(se);
|
|
|
|
/*
|
|
* Load tracking: accumulate removed load so that it can be processed
|
|
* when we next update owning cfs_rq under rq->lock. Tasks contribute
|
|
* to blocked load iff they have a positive decay-count. It can never
|
|
* be negative here since on-rq tasks have decay-count == 0.
|
|
*/
|
|
if (se->avg.decay_count) {
|
|
se->avg.decay_count = -__synchronize_entity_decay(se);
|
|
atomic64_add(se->avg.load_avg_contrib, &cfs_rq->removed_load);
|
|
}
|
|
}
|
|
#endif
|
|
#endif /* CONFIG_SMP */
|
|
|
|
static unsigned long
|
|
wakeup_gran(struct sched_entity *curr, struct sched_entity *se)
|
|
{
|
|
unsigned long gran = sysctl_sched_wakeup_granularity;
|
|
|
|
/*
|
|
* Since its curr running now, convert the gran from real-time
|
|
* to virtual-time in his units.
|
|
*
|
|
* By using 'se' instead of 'curr' we penalize light tasks, so
|
|
* they get preempted easier. That is, if 'se' < 'curr' then
|
|
* the resulting gran will be larger, therefore penalizing the
|
|
* lighter, if otoh 'se' > 'curr' then the resulting gran will
|
|
* be smaller, again penalizing the lighter task.
|
|
*
|
|
* This is especially important for buddies when the leftmost
|
|
* task is higher priority than the buddy.
|
|
*/
|
|
return calc_delta_fair(gran, se);
|
|
}
|
|
|
|
/*
|
|
* Should 'se' preempt 'curr'.
|
|
*
|
|
* |s1
|
|
* |s2
|
|
* |s3
|
|
* g
|
|
* |<--->|c
|
|
*
|
|
* w(c, s1) = -1
|
|
* w(c, s2) = 0
|
|
* w(c, s3) = 1
|
|
*
|
|
*/
|
|
static int
|
|
wakeup_preempt_entity(struct sched_entity *curr, struct sched_entity *se)
|
|
{
|
|
s64 gran, vdiff = curr->vruntime - se->vruntime;
|
|
|
|
if (vdiff <= 0)
|
|
return -1;
|
|
|
|
gran = wakeup_gran(curr, se);
|
|
if (vdiff > gran)
|
|
return 1;
|
|
|
|
return 0;
|
|
}
|
|
|
|
static void set_last_buddy(struct sched_entity *se)
|
|
{
|
|
if (entity_is_task(se) && unlikely(task_of(se)->policy == SCHED_IDLE))
|
|
return;
|
|
|
|
for_each_sched_entity(se)
|
|
cfs_rq_of(se)->last = se;
|
|
}
|
|
|
|
static void set_next_buddy(struct sched_entity *se)
|
|
{
|
|
if (entity_is_task(se) && unlikely(task_of(se)->policy == SCHED_IDLE))
|
|
return;
|
|
|
|
for_each_sched_entity(se)
|
|
cfs_rq_of(se)->next = se;
|
|
}
|
|
|
|
static void set_skip_buddy(struct sched_entity *se)
|
|
{
|
|
for_each_sched_entity(se)
|
|
cfs_rq_of(se)->skip = se;
|
|
}
|
|
|
|
/*
|
|
* Preempt the current task with a newly woken task if needed:
|
|
*/
|
|
static void check_preempt_wakeup(struct rq *rq, struct task_struct *p, int wake_flags)
|
|
{
|
|
struct task_struct *curr = rq->curr;
|
|
struct sched_entity *se = &curr->se, *pse = &p->se;
|
|
struct cfs_rq *cfs_rq = task_cfs_rq(curr);
|
|
int scale = cfs_rq->nr_running >= sched_nr_latency;
|
|
int next_buddy_marked = 0;
|
|
|
|
if (unlikely(se == pse))
|
|
return;
|
|
|
|
/*
|
|
* This is possible from callers such as move_task(), in which we
|
|
* unconditionally check_prempt_curr() after an enqueue (which may have
|
|
* lead to a throttle). This both saves work and prevents false
|
|
* next-buddy nomination below.
|
|
*/
|
|
if (unlikely(throttled_hierarchy(cfs_rq_of(pse))))
|
|
return;
|
|
|
|
if (sched_feat(NEXT_BUDDY) && scale && !(wake_flags & WF_FORK)) {
|
|
set_next_buddy(pse);
|
|
next_buddy_marked = 1;
|
|
}
|
|
|
|
/*
|
|
* We can come here with TIF_NEED_RESCHED already set from new task
|
|
* wake up path.
|
|
*
|
|
* Note: this also catches the edge-case of curr being in a throttled
|
|
* group (e.g. via set_curr_task), since update_curr() (in the
|
|
* enqueue of curr) will have resulted in resched being set. This
|
|
* prevents us from potentially nominating it as a false LAST_BUDDY
|
|
* below.
|
|
*/
|
|
if (test_tsk_need_resched(curr))
|
|
return;
|
|
|
|
/* Idle tasks are by definition preempted by non-idle tasks. */
|
|
if (unlikely(curr->policy == SCHED_IDLE) &&
|
|
likely(p->policy != SCHED_IDLE))
|
|
goto preempt;
|
|
|
|
/*
|
|
* Batch and idle tasks do not preempt non-idle tasks (their preemption
|
|
* is driven by the tick):
|
|
*/
|
|
if (unlikely(p->policy != SCHED_NORMAL) || !sched_feat(WAKEUP_PREEMPTION))
|
|
return;
|
|
|
|
find_matching_se(&se, &pse);
|
|
update_curr(cfs_rq_of(se));
|
|
BUG_ON(!pse);
|
|
if (wakeup_preempt_entity(se, pse) == 1) {
|
|
/*
|
|
* Bias pick_next to pick the sched entity that is
|
|
* triggering this preemption.
|
|
*/
|
|
if (!next_buddy_marked)
|
|
set_next_buddy(pse);
|
|
goto preempt;
|
|
}
|
|
|
|
return;
|
|
|
|
preempt:
|
|
resched_task(curr);
|
|
/*
|
|
* Only set the backward buddy when the current task is still
|
|
* on the rq. This can happen when a wakeup gets interleaved
|
|
* with schedule on the ->pre_schedule() or idle_balance()
|
|
* point, either of which can * drop the rq lock.
|
|
*
|
|
* Also, during early boot the idle thread is in the fair class,
|
|
* for obvious reasons its a bad idea to schedule back to it.
|
|
*/
|
|
if (unlikely(!se->on_rq || curr == rq->idle))
|
|
return;
|
|
|
|
if (sched_feat(LAST_BUDDY) && scale && entity_is_task(se))
|
|
set_last_buddy(se);
|
|
}
|
|
|
|
static struct task_struct *pick_next_task_fair(struct rq *rq)
|
|
{
|
|
struct task_struct *p;
|
|
struct cfs_rq *cfs_rq = &rq->cfs;
|
|
struct sched_entity *se;
|
|
|
|
if (!cfs_rq->nr_running)
|
|
return NULL;
|
|
|
|
do {
|
|
se = pick_next_entity(cfs_rq);
|
|
set_next_entity(cfs_rq, se);
|
|
cfs_rq = group_cfs_rq(se);
|
|
} while (cfs_rq);
|
|
|
|
p = task_of(se);
|
|
if (hrtick_enabled(rq))
|
|
hrtick_start_fair(rq, p);
|
|
|
|
return p;
|
|
}
|
|
|
|
/*
|
|
* Account for a descheduled task:
|
|
*/
|
|
static void put_prev_task_fair(struct rq *rq, struct task_struct *prev)
|
|
{
|
|
struct sched_entity *se = &prev->se;
|
|
struct cfs_rq *cfs_rq;
|
|
|
|
for_each_sched_entity(se) {
|
|
cfs_rq = cfs_rq_of(se);
|
|
put_prev_entity(cfs_rq, se);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* sched_yield() is very simple
|
|
*
|
|
* The magic of dealing with the ->skip buddy is in pick_next_entity.
|
|
*/
|
|
static void yield_task_fair(struct rq *rq)
|
|
{
|
|
struct task_struct *curr = rq->curr;
|
|
struct cfs_rq *cfs_rq = task_cfs_rq(curr);
|
|
struct sched_entity *se = &curr->se;
|
|
|
|
/*
|
|
* Are we the only task in the tree?
|
|
*/
|
|
if (unlikely(rq->nr_running == 1))
|
|
return;
|
|
|
|
clear_buddies(cfs_rq, se);
|
|
|
|
if (curr->policy != SCHED_BATCH) {
|
|
update_rq_clock(rq);
|
|
/*
|
|
* Update run-time statistics of the 'current'.
|
|
*/
|
|
update_curr(cfs_rq);
|
|
/*
|
|
* Tell update_rq_clock() that we've just updated,
|
|
* so we don't do microscopic update in schedule()
|
|
* and double the fastpath cost.
|
|
*/
|
|
rq->skip_clock_update = 1;
|
|
}
|
|
|
|
set_skip_buddy(se);
|
|
}
|
|
|
|
static bool yield_to_task_fair(struct rq *rq, struct task_struct *p, bool preempt)
|
|
{
|
|
struct sched_entity *se = &p->se;
|
|
|
|
/* throttled hierarchies are not runnable */
|
|
if (!se->on_rq || throttled_hierarchy(cfs_rq_of(se)))
|
|
return false;
|
|
|
|
/* Tell the scheduler that we'd really like pse to run next. */
|
|
set_next_buddy(se);
|
|
|
|
yield_task_fair(rq);
|
|
|
|
return true;
|
|
}
|
|
|
|
#ifdef CONFIG_SMP
|
|
/**************************************************
|
|
* Fair scheduling class load-balancing methods.
|
|
*
|
|
* BASICS
|
|
*
|
|
* The purpose of load-balancing is to achieve the same basic fairness the
|
|
* per-cpu scheduler provides, namely provide a proportional amount of compute
|
|
* time to each task. This is expressed in the following equation:
|
|
*
|
|
* W_i,n/P_i == W_j,n/P_j for all i,j (1)
|
|
*
|
|
* Where W_i,n is the n-th weight average for cpu i. The instantaneous weight
|
|
* W_i,0 is defined as:
|
|
*
|
|
* W_i,0 = \Sum_j w_i,j (2)
|
|
*
|
|
* Where w_i,j is the weight of the j-th runnable task on cpu i. This weight
|
|
* is derived from the nice value as per prio_to_weight[].
|
|
*
|
|
* The weight average is an exponential decay average of the instantaneous
|
|
* weight:
|
|
*
|
|
* W'_i,n = (2^n - 1) / 2^n * W_i,n + 1 / 2^n * W_i,0 (3)
|
|
*
|
|
* P_i is the cpu power (or compute capacity) of cpu i, typically it is the
|
|
* fraction of 'recent' time available for SCHED_OTHER task execution. But it
|
|
* can also include other factors [XXX].
|
|
*
|
|
* To achieve this balance we define a measure of imbalance which follows
|
|
* directly from (1):
|
|
*
|
|
* imb_i,j = max{ avg(W/P), W_i/P_i } - min{ avg(W/P), W_j/P_j } (4)
|
|
*
|
|
* We them move tasks around to minimize the imbalance. In the continuous
|
|
* function space it is obvious this converges, in the discrete case we get
|
|
* a few fun cases generally called infeasible weight scenarios.
|
|
*
|
|
* [XXX expand on:
|
|
* - infeasible weights;
|
|
* - local vs global optima in the discrete case. ]
|
|
*
|
|
*
|
|
* SCHED DOMAINS
|
|
*
|
|
* In order to solve the imbalance equation (4), and avoid the obvious O(n^2)
|
|
* for all i,j solution, we create a tree of cpus that follows the hardware
|
|
* topology where each level pairs two lower groups (or better). This results
|
|
* in O(log n) layers. Furthermore we reduce the number of cpus going up the
|
|
* tree to only the first of the previous level and we decrease the frequency
|
|
* of load-balance at each level inv. proportional to the number of cpus in
|
|
* the groups.
|
|
*
|
|
* This yields:
|
|
*
|
|
* log_2 n 1 n
|
|
* \Sum { --- * --- * 2^i } = O(n) (5)
|
|
* i = 0 2^i 2^i
|
|
* `- size of each group
|
|
* | | `- number of cpus doing load-balance
|
|
* | `- freq
|
|
* `- sum over all levels
|
|
*
|
|
* Coupled with a limit on how many tasks we can migrate every balance pass,
|
|
* this makes (5) the runtime complexity of the balancer.
|
|
*
|
|
* An important property here is that each CPU is still (indirectly) connected
|
|
* to every other cpu in at most O(log n) steps:
|
|
*
|
|
* The adjacency matrix of the resulting graph is given by:
|
|
*
|
|
* log_2 n
|
|
* A_i,j = \Union (i % 2^k == 0) && i / 2^(k+1) == j / 2^(k+1) (6)
|
|
* k = 0
|
|
*
|
|
* And you'll find that:
|
|
*
|
|
* A^(log_2 n)_i,j != 0 for all i,j (7)
|
|
*
|
|
* Showing there's indeed a path between every cpu in at most O(log n) steps.
|
|
* The task movement gives a factor of O(m), giving a convergence complexity
|
|
* of:
|
|
*
|
|
* O(nm log n), n := nr_cpus, m := nr_tasks (8)
|
|
*
|
|
*
|
|
* WORK CONSERVING
|
|
*
|
|
* In order to avoid CPUs going idle while there's still work to do, new idle
|
|
* balancing is more aggressive and has the newly idle cpu iterate up the domain
|
|
* tree itself instead of relying on other CPUs to bring it work.
|
|
*
|
|
* This adds some complexity to both (5) and (8) but it reduces the total idle
|
|
* time.
|
|
*
|
|
* [XXX more?]
|
|
*
|
|
*
|
|
* CGROUPS
|
|
*
|
|
* Cgroups make a horror show out of (2), instead of a simple sum we get:
|
|
*
|
|
* s_k,i
|
|
* W_i,0 = \Sum_j \Prod_k w_k * ----- (9)
|
|
* S_k
|
|
*
|
|
* Where
|
|
*
|
|
* s_k,i = \Sum_j w_i,j,k and S_k = \Sum_i s_k,i (10)
|
|
*
|
|
* w_i,j,k is the weight of the j-th runnable task in the k-th cgroup on cpu i.
|
|
*
|
|
* The big problem is S_k, its a global sum needed to compute a local (W_i)
|
|
* property.
|
|
*
|
|
* [XXX write more on how we solve this.. _after_ merging pjt's patches that
|
|
* rewrite all of this once again.]
|
|
*/
|
|
|
|
static unsigned long __read_mostly max_load_balance_interval = HZ/10;
|
|
|
|
#define LBF_ALL_PINNED 0x01
|
|
#define LBF_NEED_BREAK 0x02
|
|
#define LBF_SOME_PINNED 0x04
|
|
|
|
struct lb_env {
|
|
struct sched_domain *sd;
|
|
|
|
struct rq *src_rq;
|
|
int src_cpu;
|
|
|
|
int dst_cpu;
|
|
struct rq *dst_rq;
|
|
|
|
struct cpumask *dst_grpmask;
|
|
int new_dst_cpu;
|
|
enum cpu_idle_type idle;
|
|
long imbalance;
|
|
/* The set of CPUs under consideration for load-balancing */
|
|
struct cpumask *cpus;
|
|
|
|
unsigned int flags;
|
|
|
|
unsigned int loop;
|
|
unsigned int loop_break;
|
|
unsigned int loop_max;
|
|
};
|
|
|
|
/*
|
|
* move_task - move a task from one runqueue to another runqueue.
|
|
* Both runqueues must be locked.
|
|
*/
|
|
static void move_task(struct task_struct *p, struct lb_env *env)
|
|
{
|
|
deactivate_task(env->src_rq, p, 0);
|
|
set_task_cpu(p, env->dst_cpu);
|
|
activate_task(env->dst_rq, p, 0);
|
|
check_preempt_curr(env->dst_rq, p, 0);
|
|
}
|
|
|
|
/*
|
|
* Is this task likely cache-hot:
|
|
*/
|
|
static int
|
|
task_hot(struct task_struct *p, u64 now, struct sched_domain *sd)
|
|
{
|
|
s64 delta;
|
|
|
|
if (p->sched_class != &fair_sched_class)
|
|
return 0;
|
|
|
|
if (unlikely(p->policy == SCHED_IDLE))
|
|
return 0;
|
|
|
|
/*
|
|
* Buddy candidates are cache hot:
|
|
*/
|
|
if (sched_feat(CACHE_HOT_BUDDY) && this_rq()->nr_running &&
|
|
(&p->se == cfs_rq_of(&p->se)->next ||
|
|
&p->se == cfs_rq_of(&p->se)->last))
|
|
return 1;
|
|
|
|
if (sysctl_sched_migration_cost == -1)
|
|
return 1;
|
|
if (sysctl_sched_migration_cost == 0)
|
|
return 0;
|
|
|
|
delta = now - p->se.exec_start;
|
|
|
|
return delta < (s64)sysctl_sched_migration_cost;
|
|
}
|
|
|
|
/*
|
|
* can_migrate_task - may task p from runqueue rq be migrated to this_cpu?
|
|
*/
|
|
static
|
|
int can_migrate_task(struct task_struct *p, struct lb_env *env)
|
|
{
|
|
int tsk_cache_hot = 0;
|
|
/*
|
|
* We do not migrate tasks that are:
|
|
* 1) throttled_lb_pair, or
|
|
* 2) cannot be migrated to this CPU due to cpus_allowed, or
|
|
* 3) running (obviously), or
|
|
* 4) are cache-hot on their current CPU.
|
|
*/
|
|
if (throttled_lb_pair(task_group(p), env->src_cpu, env->dst_cpu))
|
|
return 0;
|
|
|
|
if (!cpumask_test_cpu(env->dst_cpu, tsk_cpus_allowed(p))) {
|
|
int cpu;
|
|
|
|
schedstat_inc(p, se.statistics.nr_failed_migrations_affine);
|
|
|
|
/*
|
|
* Remember if this task can be migrated to any other cpu in
|
|
* our sched_group. We may want to revisit it if we couldn't
|
|
* meet load balance goals by pulling other tasks on src_cpu.
|
|
*
|
|
* Also avoid computing new_dst_cpu if we have already computed
|
|
* one in current iteration.
|
|
*/
|
|
if (!env->dst_grpmask || (env->flags & LBF_SOME_PINNED))
|
|
return 0;
|
|
|
|
/* Prevent to re-select dst_cpu via env's cpus */
|
|
for_each_cpu_and(cpu, env->dst_grpmask, env->cpus) {
|
|
if (cpumask_test_cpu(cpu, tsk_cpus_allowed(p))) {
|
|
env->flags |= LBF_SOME_PINNED;
|
|
env->new_dst_cpu = cpu;
|
|
break;
|
|
}
|
|
}
|
|
|
|
return 0;
|
|
}
|
|
|
|
/* Record that we found atleast one task that could run on dst_cpu */
|
|
env->flags &= ~LBF_ALL_PINNED;
|
|
|
|
if (task_running(env->src_rq, p)) {
|
|
schedstat_inc(p, se.statistics.nr_failed_migrations_running);
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* Aggressive migration if:
|
|
* 1) task is cache cold, or
|
|
* 2) too many balance attempts have failed.
|
|
*/
|
|
|
|
tsk_cache_hot = task_hot(p, env->src_rq->clock_task, env->sd);
|
|
if (!tsk_cache_hot ||
|
|
env->sd->nr_balance_failed > env->sd->cache_nice_tries) {
|
|
|
|
if (tsk_cache_hot) {
|
|
schedstat_inc(env->sd, lb_hot_gained[env->idle]);
|
|
schedstat_inc(p, se.statistics.nr_forced_migrations);
|
|
}
|
|
|
|
return 1;
|
|
}
|
|
|
|
schedstat_inc(p, se.statistics.nr_failed_migrations_hot);
|
|
return 0;
|
|
}
|
|
|
|
/*
|
|
* move_one_task tries to move exactly one task from busiest to this_rq, as
|
|
* part of active balancing operations within "domain".
|
|
* Returns 1 if successful and 0 otherwise.
|
|
*
|
|
* Called with both runqueues locked.
|
|
*/
|
|
static int move_one_task(struct lb_env *env)
|
|
{
|
|
struct task_struct *p, *n;
|
|
|
|
list_for_each_entry_safe(p, n, &env->src_rq->cfs_tasks, se.group_node) {
|
|
if (!can_migrate_task(p, env))
|
|
continue;
|
|
|
|
move_task(p, env);
|
|
/*
|
|
* Right now, this is only the second place move_task()
|
|
* is called, so we can safely collect move_task()
|
|
* stats here rather than inside move_task().
|
|
*/
|
|
schedstat_inc(env->sd, lb_gained[env->idle]);
|
|
return 1;
|
|
}
|
|
return 0;
|
|
}
|
|
|
|
static unsigned long task_h_load(struct task_struct *p);
|
|
|
|
static const unsigned int sched_nr_migrate_break = 32;
|
|
|
|
/*
|
|
* move_tasks tries to move up to imbalance weighted load from busiest to
|
|
* this_rq, as part of a balancing operation within domain "sd".
|
|
* Returns 1 if successful and 0 otherwise.
|
|
*
|
|
* Called with both runqueues locked.
|
|
*/
|
|
static int move_tasks(struct lb_env *env)
|
|
{
|
|
struct list_head *tasks = &env->src_rq->cfs_tasks;
|
|
struct task_struct *p;
|
|
unsigned long load;
|
|
int pulled = 0;
|
|
|
|
if (env->imbalance <= 0)
|
|
return 0;
|
|
|
|
while (!list_empty(tasks)) {
|
|
p = list_first_entry(tasks, struct task_struct, se.group_node);
|
|
|
|
env->loop++;
|
|
/* We've more or less seen every task there is, call it quits */
|
|
if (env->loop > env->loop_max)
|
|
break;
|
|
|
|
/* take a breather every nr_migrate tasks */
|
|
if (env->loop > env->loop_break) {
|
|
env->loop_break += sched_nr_migrate_break;
|
|
env->flags |= LBF_NEED_BREAK;
|
|
break;
|
|
}
|
|
|
|
if (!can_migrate_task(p, env))
|
|
goto next;
|
|
|
|
load = task_h_load(p);
|
|
|
|
if (sched_feat(LB_MIN) && load < 16 && !env->sd->nr_balance_failed)
|
|
goto next;
|
|
|
|
if ((load / 2) > env->imbalance)
|
|
goto next;
|
|
|
|
move_task(p, env);
|
|
pulled++;
|
|
env->imbalance -= load;
|
|
|
|
#ifdef CONFIG_PREEMPT
|
|
/*
|
|
* NEWIDLE balancing is a source of latency, so preemptible
|
|
* kernels will stop after the first task is pulled to minimize
|
|
* the critical section.
|
|
*/
|
|
if (env->idle == CPU_NEWLY_IDLE)
|
|
break;
|
|
#endif
|
|
|
|
/*
|
|
* We only want to steal up to the prescribed amount of
|
|
* weighted load.
|
|
*/
|
|
if (env->imbalance <= 0)
|
|
break;
|
|
|
|
continue;
|
|
next:
|
|
list_move_tail(&p->se.group_node, tasks);
|
|
}
|
|
|
|
/*
|
|
* Right now, this is one of only two places move_task() is called,
|
|
* so we can safely collect move_task() stats here rather than
|
|
* inside move_task().
|
|
*/
|
|
schedstat_add(env->sd, lb_gained[env->idle], pulled);
|
|
|
|
return pulled;
|
|
}
|
|
|
|
#ifdef CONFIG_FAIR_GROUP_SCHED
|
|
/*
|
|
* update tg->load_weight by folding this cpu's load_avg
|
|
*/
|
|
static void __update_blocked_averages_cpu(struct task_group *tg, int cpu)
|
|
{
|
|
struct sched_entity *se = tg->se[cpu];
|
|
struct cfs_rq *cfs_rq = tg->cfs_rq[cpu];
|
|
|
|
/* throttled entities do not contribute to load */
|
|
if (throttled_hierarchy(cfs_rq))
|
|
return;
|
|
|
|
update_cfs_rq_blocked_load(cfs_rq, 1);
|
|
|
|
if (se) {
|
|
update_entity_load_avg(se, 1);
|
|
/*
|
|
* We pivot on our runnable average having decayed to zero for
|
|
* list removal. This generally implies that all our children
|
|
* have also been removed (modulo rounding error or bandwidth
|
|
* control); however, such cases are rare and we can fix these
|
|
* at enqueue.
|
|
*
|
|
* TODO: fix up out-of-order children on enqueue.
|
|
*/
|
|
if (!se->avg.runnable_avg_sum && !cfs_rq->nr_running)
|
|
list_del_leaf_cfs_rq(cfs_rq);
|
|
} else {
|
|
struct rq *rq = rq_of(cfs_rq);
|
|
update_rq_runnable_avg(rq, rq->nr_running);
|
|
}
|
|
}
|
|
|
|
static void update_blocked_averages(int cpu)
|
|
{
|
|
struct rq *rq = cpu_rq(cpu);
|
|
struct cfs_rq *cfs_rq;
|
|
unsigned long flags;
|
|
|
|
raw_spin_lock_irqsave(&rq->lock, flags);
|
|
update_rq_clock(rq);
|
|
/*
|
|
* Iterates the task_group tree in a bottom up fashion, see
|
|
* list_add_leaf_cfs_rq() for details.
|
|
*/
|
|
for_each_leaf_cfs_rq(rq, cfs_rq) {
|
|
/*
|
|
* Note: We may want to consider periodically releasing
|
|
* rq->lock about these updates so that creating many task
|
|
* groups does not result in continually extending hold time.
|
|
*/
|
|
__update_blocked_averages_cpu(cfs_rq->tg, rq->cpu);
|
|
}
|
|
|
|
raw_spin_unlock_irqrestore(&rq->lock, flags);
|
|
}
|
|
|
|
/*
|
|
* Compute the cpu's hierarchical load factor for each task group.
|
|
* This needs to be done in a top-down fashion because the load of a child
|
|
* group is a fraction of its parents load.
|
|
*/
|
|
static int tg_load_down(struct task_group *tg, void *data)
|
|
{
|
|
unsigned long load;
|
|
long cpu = (long)data;
|
|
|
|
if (!tg->parent) {
|
|
load = cpu_rq(cpu)->load.weight;
|
|
} else {
|
|
load = tg->parent->cfs_rq[cpu]->h_load;
|
|
load *= tg->se[cpu]->load.weight;
|
|
load /= tg->parent->cfs_rq[cpu]->load.weight + 1;
|
|
}
|
|
|
|
tg->cfs_rq[cpu]->h_load = load;
|
|
|
|
return 0;
|
|
}
|
|
|
|
static void update_h_load(long cpu)
|
|
{
|
|
struct rq *rq = cpu_rq(cpu);
|
|
unsigned long now = jiffies;
|
|
|
|
if (rq->h_load_throttle == now)
|
|
return;
|
|
|
|
rq->h_load_throttle = now;
|
|
|
|
rcu_read_lock();
|
|
walk_tg_tree(tg_load_down, tg_nop, (void *)cpu);
|
|
rcu_read_unlock();
|
|
}
|
|
|
|
static unsigned long task_h_load(struct task_struct *p)
|
|
{
|
|
struct cfs_rq *cfs_rq = task_cfs_rq(p);
|
|
unsigned long load;
|
|
|
|
load = p->se.load.weight;
|
|
load = div_u64(load * cfs_rq->h_load, cfs_rq->load.weight + 1);
|
|
|
|
return load;
|
|
}
|
|
#else
|
|
static inline void update_blocked_averages(int cpu)
|
|
{
|
|
}
|
|
|
|
static inline void update_h_load(long cpu)
|
|
{
|
|
}
|
|
|
|
static unsigned long task_h_load(struct task_struct *p)
|
|
{
|
|
return p->se.load.weight;
|
|
}
|
|
#endif
|
|
|
|
/********** Helpers for find_busiest_group ************************/
|
|
/*
|
|
* sd_lb_stats - Structure to store the statistics of a sched_domain
|
|
* during load balancing.
|
|
*/
|
|
struct sd_lb_stats {
|
|
struct sched_group *busiest; /* Busiest group in this sd */
|
|
struct sched_group *this; /* Local group in this sd */
|
|
unsigned long total_load; /* Total load of all groups in sd */
|
|
unsigned long total_pwr; /* Total power of all groups in sd */
|
|
unsigned long avg_load; /* Average load across all groups in sd */
|
|
|
|
/** Statistics of this group */
|
|
unsigned long this_load;
|
|
unsigned long this_load_per_task;
|
|
unsigned long this_nr_running;
|
|
unsigned long this_has_capacity;
|
|
unsigned int this_idle_cpus;
|
|
|
|
/* Statistics of the busiest group */
|
|
unsigned int busiest_idle_cpus;
|
|
unsigned long max_load;
|
|
unsigned long busiest_load_per_task;
|
|
unsigned long busiest_nr_running;
|
|
unsigned long busiest_group_capacity;
|
|
unsigned long busiest_has_capacity;
|
|
unsigned int busiest_group_weight;
|
|
|
|
int group_imb; /* Is there imbalance in this sd */
|
|
};
|
|
|
|
/*
|
|
* sg_lb_stats - stats of a sched_group required for load_balancing
|
|
*/
|
|
struct sg_lb_stats {
|
|
unsigned long avg_load; /*Avg load across the CPUs of the group */
|
|
unsigned long group_load; /* Total load over the CPUs of the group */
|
|
unsigned long sum_nr_running; /* Nr tasks running in the group */
|
|
unsigned long sum_weighted_load; /* Weighted load of group's tasks */
|
|
unsigned long group_capacity;
|
|
unsigned long idle_cpus;
|
|
unsigned long group_weight;
|
|
int group_imb; /* Is there an imbalance in the group ? */
|
|
int group_has_capacity; /* Is there extra capacity in the group? */
|
|
};
|
|
|
|
/**
|
|
* get_sd_load_idx - Obtain the load index for a given sched domain.
|
|
* @sd: The sched_domain whose load_idx is to be obtained.
|
|
* @idle: The Idle status of the CPU for whose sd load_icx is obtained.
|
|
*/
|
|
static inline int get_sd_load_idx(struct sched_domain *sd,
|
|
enum cpu_idle_type idle)
|
|
{
|
|
int load_idx;
|
|
|
|
switch (idle) {
|
|
case CPU_NOT_IDLE:
|
|
load_idx = sd->busy_idx;
|
|
break;
|
|
|
|
case CPU_NEWLY_IDLE:
|
|
load_idx = sd->newidle_idx;
|
|
break;
|
|
default:
|
|
load_idx = sd->idle_idx;
|
|
break;
|
|
}
|
|
|
|
return load_idx;
|
|
}
|
|
|
|
static unsigned long default_scale_freq_power(struct sched_domain *sd, int cpu)
|
|
{
|
|
return SCHED_POWER_SCALE;
|
|
}
|
|
|
|
unsigned long __weak arch_scale_freq_power(struct sched_domain *sd, int cpu)
|
|
{
|
|
return default_scale_freq_power(sd, cpu);
|
|
}
|
|
|
|
static unsigned long default_scale_smt_power(struct sched_domain *sd, int cpu)
|
|
{
|
|
unsigned long weight = sd->span_weight;
|
|
unsigned long smt_gain = sd->smt_gain;
|
|
|
|
smt_gain /= weight;
|
|
|
|
return smt_gain;
|
|
}
|
|
|
|
unsigned long __weak arch_scale_smt_power(struct sched_domain *sd, int cpu)
|
|
{
|
|
return default_scale_smt_power(sd, cpu);
|
|
}
|
|
|
|
static unsigned long scale_rt_power(int cpu)
|
|
{
|
|
struct rq *rq = cpu_rq(cpu);
|
|
u64 total, available, age_stamp, avg;
|
|
|
|
/*
|
|
* Since we're reading these variables without serialization make sure
|
|
* we read them once before doing sanity checks on them.
|
|
*/
|
|
age_stamp = ACCESS_ONCE(rq->age_stamp);
|
|
avg = ACCESS_ONCE(rq->rt_avg);
|
|
|
|
total = sched_avg_period() + (rq->clock - age_stamp);
|
|
|
|
if (unlikely(total < avg)) {
|
|
/* Ensures that power won't end up being negative */
|
|
available = 0;
|
|
} else {
|
|
available = total - avg;
|
|
}
|
|
|
|
if (unlikely((s64)total < SCHED_POWER_SCALE))
|
|
total = SCHED_POWER_SCALE;
|
|
|
|
total >>= SCHED_POWER_SHIFT;
|
|
|
|
return div_u64(available, total);
|
|
}
|
|
|
|
static void update_cpu_power(struct sched_domain *sd, int cpu)
|
|
{
|
|
unsigned long weight = sd->span_weight;
|
|
unsigned long power = SCHED_POWER_SCALE;
|
|
struct sched_group *sdg = sd->groups;
|
|
|
|
if ((sd->flags & SD_SHARE_CPUPOWER) && weight > 1) {
|
|
if (sched_feat(ARCH_POWER))
|
|
power *= arch_scale_smt_power(sd, cpu);
|
|
else
|
|
power *= default_scale_smt_power(sd, cpu);
|
|
|
|
power >>= SCHED_POWER_SHIFT;
|
|
}
|
|
|
|
sdg->sgp->power_orig = power;
|
|
|
|
if (sched_feat(ARCH_POWER))
|
|
power *= arch_scale_freq_power(sd, cpu);
|
|
else
|
|
power *= default_scale_freq_power(sd, cpu);
|
|
|
|
power >>= SCHED_POWER_SHIFT;
|
|
|
|
power *= scale_rt_power(cpu);
|
|
power >>= SCHED_POWER_SHIFT;
|
|
|
|
if (!power)
|
|
power = 1;
|
|
|
|
cpu_rq(cpu)->cpu_power = power;
|
|
sdg->sgp->power = power;
|
|
}
|
|
|
|
void update_group_power(struct sched_domain *sd, int cpu)
|
|
{
|
|
struct sched_domain *child = sd->child;
|
|
struct sched_group *group, *sdg = sd->groups;
|
|
unsigned long power;
|
|
unsigned long interval;
|
|
|
|
interval = msecs_to_jiffies(sd->balance_interval);
|
|
interval = clamp(interval, 1UL, max_load_balance_interval);
|
|
sdg->sgp->next_update = jiffies + interval;
|
|
|
|
if (!child) {
|
|
update_cpu_power(sd, cpu);
|
|
return;
|
|
}
|
|
|
|
power = 0;
|
|
|
|
if (child->flags & SD_OVERLAP) {
|
|
/*
|
|
* SD_OVERLAP domains cannot assume that child groups
|
|
* span the current group.
|
|
*/
|
|
|
|
for_each_cpu(cpu, sched_group_cpus(sdg))
|
|
power += power_of(cpu);
|
|
} else {
|
|
/*
|
|
* !SD_OVERLAP domains can assume that child groups
|
|
* span the current group.
|
|
*/
|
|
|
|
group = child->groups;
|
|
do {
|
|
power += group->sgp->power;
|
|
group = group->next;
|
|
} while (group != child->groups);
|
|
}
|
|
|
|
sdg->sgp->power_orig = sdg->sgp->power = power;
|
|
}
|
|
|
|
/*
|
|
* Try and fix up capacity for tiny siblings, this is needed when
|
|
* things like SD_ASYM_PACKING need f_b_g to select another sibling
|
|
* which on its own isn't powerful enough.
|
|
*
|
|
* See update_sd_pick_busiest() and check_asym_packing().
|
|
*/
|
|
static inline int
|
|
fix_small_capacity(struct sched_domain *sd, struct sched_group *group)
|
|
{
|
|
/*
|
|
* Only siblings can have significantly less than SCHED_POWER_SCALE
|
|
*/
|
|
if (!(sd->flags & SD_SHARE_CPUPOWER))
|
|
return 0;
|
|
|
|
/*
|
|
* If ~90% of the cpu_power is still there, we're good.
|
|
*/
|
|
if (group->sgp->power * 32 > group->sgp->power_orig * 29)
|
|
return 1;
|
|
|
|
return 0;
|
|
}
|
|
|
|
/**
|
|
* update_sg_lb_stats - Update sched_group's statistics for load balancing.
|
|
* @env: The load balancing environment.
|
|
* @group: sched_group whose statistics are to be updated.
|
|
* @load_idx: Load index of sched_domain of this_cpu for load calc.
|
|
* @local_group: Does group contain this_cpu.
|
|
* @balance: Should we balance.
|
|
* @sgs: variable to hold the statistics for this group.
|
|
*/
|
|
static inline void update_sg_lb_stats(struct lb_env *env,
|
|
struct sched_group *group, int load_idx,
|
|
int local_group, int *balance, struct sg_lb_stats *sgs)
|
|
{
|
|
unsigned long nr_running, max_nr_running, min_nr_running;
|
|
unsigned long load, max_cpu_load, min_cpu_load;
|
|
unsigned int balance_cpu = -1, first_idle_cpu = 0;
|
|
unsigned long avg_load_per_task = 0;
|
|
int i;
|
|
|
|
if (local_group)
|
|
balance_cpu = group_balance_cpu(group);
|
|
|
|
/* Tally up the load of all CPUs in the group */
|
|
max_cpu_load = 0;
|
|
min_cpu_load = ~0UL;
|
|
max_nr_running = 0;
|
|
min_nr_running = ~0UL;
|
|
|
|
for_each_cpu_and(i, sched_group_cpus(group), env->cpus) {
|
|
struct rq *rq = cpu_rq(i);
|
|
|
|
nr_running = rq->nr_running;
|
|
|
|
/* Bias balancing toward cpus of our domain */
|
|
if (local_group) {
|
|
if (idle_cpu(i) && !first_idle_cpu &&
|
|
cpumask_test_cpu(i, sched_group_mask(group))) {
|
|
first_idle_cpu = 1;
|
|
balance_cpu = i;
|
|
}
|
|
|
|
load = target_load(i, load_idx);
|
|
} else {
|
|
load = source_load(i, load_idx);
|
|
if (load > max_cpu_load)
|
|
max_cpu_load = load;
|
|
if (min_cpu_load > load)
|
|
min_cpu_load = load;
|
|
|
|
if (nr_running > max_nr_running)
|
|
max_nr_running = nr_running;
|
|
if (min_nr_running > nr_running)
|
|
min_nr_running = nr_running;
|
|
}
|
|
|
|
sgs->group_load += load;
|
|
sgs->sum_nr_running += nr_running;
|
|
sgs->sum_weighted_load += weighted_cpuload(i);
|
|
if (idle_cpu(i))
|
|
sgs->idle_cpus++;
|
|
}
|
|
|
|
/*
|
|
* First idle cpu or the first cpu(busiest) in this sched group
|
|
* is eligible for doing load balancing at this and above
|
|
* domains. In the newly idle case, we will allow all the cpu's
|
|
* to do the newly idle load balance.
|
|
*/
|
|
if (local_group) {
|
|
if (env->idle != CPU_NEWLY_IDLE) {
|
|
if (balance_cpu != env->dst_cpu) {
|
|
*balance = 0;
|
|
return;
|
|
}
|
|
update_group_power(env->sd, env->dst_cpu);
|
|
} else if (time_after_eq(jiffies, group->sgp->next_update))
|
|
update_group_power(env->sd, env->dst_cpu);
|
|
}
|
|
|
|
/* Adjust by relative CPU power of the group */
|
|
sgs->avg_load = (sgs->group_load*SCHED_POWER_SCALE) / group->sgp->power;
|
|
|
|
/*
|
|
* Consider the group unbalanced when the imbalance is larger
|
|
* than the average weight of a task.
|
|
*
|
|
* APZ: with cgroup the avg task weight can vary wildly and
|
|
* might not be a suitable number - should we keep a
|
|
* normalized nr_running number somewhere that negates
|
|
* the hierarchy?
|
|
*/
|
|
if (sgs->sum_nr_running)
|
|
avg_load_per_task = sgs->sum_weighted_load / sgs->sum_nr_running;
|
|
|
|
if ((max_cpu_load - min_cpu_load) >= avg_load_per_task &&
|
|
(max_nr_running - min_nr_running) > 1)
|
|
sgs->group_imb = 1;
|
|
|
|
sgs->group_capacity = DIV_ROUND_CLOSEST(group->sgp->power,
|
|
SCHED_POWER_SCALE);
|
|
if (!sgs->group_capacity)
|
|
sgs->group_capacity = fix_small_capacity(env->sd, group);
|
|
sgs->group_weight = group->group_weight;
|
|
|
|
if (sgs->group_capacity > sgs->sum_nr_running)
|
|
sgs->group_has_capacity = 1;
|
|
}
|
|
|
|
/**
|
|
* update_sd_pick_busiest - return 1 on busiest group
|
|
* @env: The load balancing environment.
|
|
* @sds: sched_domain statistics
|
|
* @sg: sched_group candidate to be checked for being the busiest
|
|
* @sgs: sched_group statistics
|
|
*
|
|
* Determine if @sg is a busier group than the previously selected
|
|
* busiest group.
|
|
*/
|
|
static bool update_sd_pick_busiest(struct lb_env *env,
|
|
struct sd_lb_stats *sds,
|
|
struct sched_group *sg,
|
|
struct sg_lb_stats *sgs)
|
|
{
|
|
if (sgs->avg_load <= sds->max_load)
|
|
return false;
|
|
|
|
if (sgs->sum_nr_running > sgs->group_capacity)
|
|
return true;
|
|
|
|
if (sgs->group_imb)
|
|
return true;
|
|
|
|
/*
|
|
* ASYM_PACKING needs to move all the work to the lowest
|
|
* numbered CPUs in the group, therefore mark all groups
|
|
* higher than ourself as busy.
|
|
*/
|
|
if ((env->sd->flags & SD_ASYM_PACKING) && sgs->sum_nr_running &&
|
|
env->dst_cpu < group_first_cpu(sg)) {
|
|
if (!sds->busiest)
|
|
return true;
|
|
|
|
if (group_first_cpu(sds->busiest) > group_first_cpu(sg))
|
|
return true;
|
|
}
|
|
|
|
return false;
|
|
}
|
|
|
|
/**
|
|
* update_sd_lb_stats - Update sched_domain's statistics for load balancing.
|
|
* @env: The load balancing environment.
|
|
* @balance: Should we balance.
|
|
* @sds: variable to hold the statistics for this sched_domain.
|
|
*/
|
|
static inline void update_sd_lb_stats(struct lb_env *env,
|
|
int *balance, struct sd_lb_stats *sds)
|
|
{
|
|
struct sched_domain *child = env->sd->child;
|
|
struct sched_group *sg = env->sd->groups;
|
|
struct sg_lb_stats sgs;
|
|
int load_idx, prefer_sibling = 0;
|
|
|
|
if (child && child->flags & SD_PREFER_SIBLING)
|
|
prefer_sibling = 1;
|
|
|
|
load_idx = get_sd_load_idx(env->sd, env->idle);
|
|
|
|
do {
|
|
int local_group;
|
|
|
|
local_group = cpumask_test_cpu(env->dst_cpu, sched_group_cpus(sg));
|
|
memset(&sgs, 0, sizeof(sgs));
|
|
update_sg_lb_stats(env, sg, load_idx, local_group, balance, &sgs);
|
|
|
|
if (local_group && !(*balance))
|
|
return;
|
|
|
|
sds->total_load += sgs.group_load;
|
|
sds->total_pwr += sg->sgp->power;
|
|
|
|
/*
|
|
* In case the child domain prefers tasks go to siblings
|
|
* first, lower the sg capacity to one so that we'll try
|
|
* and move all the excess tasks away. We lower the capacity
|
|
* of a group only if the local group has the capacity to fit
|
|
* these excess tasks, i.e. nr_running < group_capacity. The
|
|
* extra check prevents the case where you always pull from the
|
|
* heaviest group when it is already under-utilized (possible
|
|
* with a large weight task outweighs the tasks on the system).
|
|
*/
|
|
if (prefer_sibling && !local_group && sds->this_has_capacity)
|
|
sgs.group_capacity = min(sgs.group_capacity, 1UL);
|
|
|
|
if (local_group) {
|
|
sds->this_load = sgs.avg_load;
|
|
sds->this = sg;
|
|
sds->this_nr_running = sgs.sum_nr_running;
|
|
sds->this_load_per_task = sgs.sum_weighted_load;
|
|
sds->this_has_capacity = sgs.group_has_capacity;
|
|
sds->this_idle_cpus = sgs.idle_cpus;
|
|
} else if (update_sd_pick_busiest(env, sds, sg, &sgs)) {
|
|
sds->max_load = sgs.avg_load;
|
|
sds->busiest = sg;
|
|
sds->busiest_nr_running = sgs.sum_nr_running;
|
|
sds->busiest_idle_cpus = sgs.idle_cpus;
|
|
sds->busiest_group_capacity = sgs.group_capacity;
|
|
sds->busiest_load_per_task = sgs.sum_weighted_load;
|
|
sds->busiest_has_capacity = sgs.group_has_capacity;
|
|
sds->busiest_group_weight = sgs.group_weight;
|
|
sds->group_imb = sgs.group_imb;
|
|
}
|
|
|
|
sg = sg->next;
|
|
} while (sg != env->sd->groups);
|
|
}
|
|
|
|
/**
|
|
* check_asym_packing - Check to see if the group is packed into the
|
|
* sched doman.
|
|
*
|
|
* This is primarily intended to used at the sibling level. Some
|
|
* cores like POWER7 prefer to use lower numbered SMT threads. In the
|
|
* case of POWER7, it can move to lower SMT modes only when higher
|
|
* threads are idle. When in lower SMT modes, the threads will
|
|
* perform better since they share less core resources. Hence when we
|
|
* have idle threads, we want them to be the higher ones.
|
|
*
|
|
* This packing function is run on idle threads. It checks to see if
|
|
* the busiest CPU in this domain (core in the P7 case) has a higher
|
|
* CPU number than the packing function is being run on. Here we are
|
|
* assuming lower CPU number will be equivalent to lower a SMT thread
|
|
* number.
|
|
*
|
|
* Returns 1 when packing is required and a task should be moved to
|
|
* this CPU. The amount of the imbalance is returned in *imbalance.
|
|
*
|
|
* @env: The load balancing environment.
|
|
* @sds: Statistics of the sched_domain which is to be packed
|
|
*/
|
|
static int check_asym_packing(struct lb_env *env, struct sd_lb_stats *sds)
|
|
{
|
|
int busiest_cpu;
|
|
|
|
if (!(env->sd->flags & SD_ASYM_PACKING))
|
|
return 0;
|
|
|
|
if (!sds->busiest)
|
|
return 0;
|
|
|
|
busiest_cpu = group_first_cpu(sds->busiest);
|
|
if (env->dst_cpu > busiest_cpu)
|
|
return 0;
|
|
|
|
env->imbalance = DIV_ROUND_CLOSEST(
|
|
sds->max_load * sds->busiest->sgp->power, SCHED_POWER_SCALE);
|
|
|
|
return 1;
|
|
}
|
|
|
|
/**
|
|
* fix_small_imbalance - Calculate the minor imbalance that exists
|
|
* amongst the groups of a sched_domain, during
|
|
* load balancing.
|
|
* @env: The load balancing environment.
|
|
* @sds: Statistics of the sched_domain whose imbalance is to be calculated.
|
|
*/
|
|
static inline
|
|
void fix_small_imbalance(struct lb_env *env, struct sd_lb_stats *sds)
|
|
{
|
|
unsigned long tmp, pwr_now = 0, pwr_move = 0;
|
|
unsigned int imbn = 2;
|
|
unsigned long scaled_busy_load_per_task;
|
|
|
|
if (sds->this_nr_running) {
|
|
sds->this_load_per_task /= sds->this_nr_running;
|
|
if (sds->busiest_load_per_task >
|
|
sds->this_load_per_task)
|
|
imbn = 1;
|
|
} else {
|
|
sds->this_load_per_task =
|
|
cpu_avg_load_per_task(env->dst_cpu);
|
|
}
|
|
|
|
scaled_busy_load_per_task = sds->busiest_load_per_task
|
|
* SCHED_POWER_SCALE;
|
|
scaled_busy_load_per_task /= sds->busiest->sgp->power;
|
|
|
|
if (sds->max_load - sds->this_load + scaled_busy_load_per_task >=
|
|
(scaled_busy_load_per_task * imbn)) {
|
|
env->imbalance = sds->busiest_load_per_task;
|
|
return;
|
|
}
|
|
|
|
/*
|
|
* OK, we don't have enough imbalance to justify moving tasks,
|
|
* however we may be able to increase total CPU power used by
|
|
* moving them.
|
|
*/
|
|
|
|
pwr_now += sds->busiest->sgp->power *
|
|
min(sds->busiest_load_per_task, sds->max_load);
|
|
pwr_now += sds->this->sgp->power *
|
|
min(sds->this_load_per_task, sds->this_load);
|
|
pwr_now /= SCHED_POWER_SCALE;
|
|
|
|
/* Amount of load we'd subtract */
|
|
tmp = (sds->busiest_load_per_task * SCHED_POWER_SCALE) /
|
|
sds->busiest->sgp->power;
|
|
if (sds->max_load > tmp)
|
|
pwr_move += sds->busiest->sgp->power *
|
|
min(sds->busiest_load_per_task, sds->max_load - tmp);
|
|
|
|
/* Amount of load we'd add */
|
|
if (sds->max_load * sds->busiest->sgp->power <
|
|
sds->busiest_load_per_task * SCHED_POWER_SCALE)
|
|
tmp = (sds->max_load * sds->busiest->sgp->power) /
|
|
sds->this->sgp->power;
|
|
else
|
|
tmp = (sds->busiest_load_per_task * SCHED_POWER_SCALE) /
|
|
sds->this->sgp->power;
|
|
pwr_move += sds->this->sgp->power *
|
|
min(sds->this_load_per_task, sds->this_load + tmp);
|
|
pwr_move /= SCHED_POWER_SCALE;
|
|
|
|
/* Move if we gain throughput */
|
|
if (pwr_move > pwr_now)
|
|
env->imbalance = sds->busiest_load_per_task;
|
|
}
|
|
|
|
/**
|
|
* calculate_imbalance - Calculate the amount of imbalance present within the
|
|
* groups of a given sched_domain during load balance.
|
|
* @env: load balance environment
|
|
* @sds: statistics of the sched_domain whose imbalance is to be calculated.
|
|
*/
|
|
static inline void calculate_imbalance(struct lb_env *env, struct sd_lb_stats *sds)
|
|
{
|
|
unsigned long max_pull, load_above_capacity = ~0UL;
|
|
|
|
sds->busiest_load_per_task /= sds->busiest_nr_running;
|
|
if (sds->group_imb) {
|
|
sds->busiest_load_per_task =
|
|
min(sds->busiest_load_per_task, sds->avg_load);
|
|
}
|
|
|
|
/*
|
|
* In the presence of smp nice balancing, certain scenarios can have
|
|
* max load less than avg load(as we skip the groups at or below
|
|
* its cpu_power, while calculating max_load..)
|
|
*/
|
|
if (sds->max_load < sds->avg_load) {
|
|
env->imbalance = 0;
|
|
return fix_small_imbalance(env, sds);
|
|
}
|
|
|
|
if (!sds->group_imb) {
|
|
/*
|
|
* Don't want to pull so many tasks that a group would go idle.
|
|
*/
|
|
load_above_capacity = (sds->busiest_nr_running -
|
|
sds->busiest_group_capacity);
|
|
|
|
load_above_capacity *= (SCHED_LOAD_SCALE * SCHED_POWER_SCALE);
|
|
|
|
load_above_capacity /= sds->busiest->sgp->power;
|
|
}
|
|
|
|
/*
|
|
* We're trying to get all the cpus to the average_load, so we don't
|
|
* want to push ourselves above the average load, nor do we wish to
|
|
* reduce the max loaded cpu below the average load. At the same time,
|
|
* we also don't want to reduce the group load below the group capacity
|
|
* (so that we can implement power-savings policies etc). Thus we look
|
|
* for the minimum possible imbalance.
|
|
* Be careful of negative numbers as they'll appear as very large values
|
|
* with unsigned longs.
|
|
*/
|
|
max_pull = min(sds->max_load - sds->avg_load, load_above_capacity);
|
|
|
|
/* How much load to actually move to equalise the imbalance */
|
|
env->imbalance = min(max_pull * sds->busiest->sgp->power,
|
|
(sds->avg_load - sds->this_load) * sds->this->sgp->power)
|
|
/ SCHED_POWER_SCALE;
|
|
|
|
/*
|
|
* if *imbalance is less than the average load per runnable task
|
|
* there is no guarantee that any tasks will be moved so we'll have
|
|
* a think about bumping its value to force at least one task to be
|
|
* moved
|
|
*/
|
|
if (env->imbalance < sds->busiest_load_per_task)
|
|
return fix_small_imbalance(env, sds);
|
|
|
|
}
|
|
|
|
/******* find_busiest_group() helpers end here *********************/
|
|
|
|
/**
|
|
* find_busiest_group - Returns the busiest group within the sched_domain
|
|
* if there is an imbalance. If there isn't an imbalance, and
|
|
* the user has opted for power-savings, it returns a group whose
|
|
* CPUs can be put to idle by rebalancing those tasks elsewhere, if
|
|
* such a group exists.
|
|
*
|
|
* Also calculates the amount of weighted load which should be moved
|
|
* to restore balance.
|
|
*
|
|
* @env: The load balancing environment.
|
|
* @balance: Pointer to a variable indicating if this_cpu
|
|
* is the appropriate cpu to perform load balancing at this_level.
|
|
*
|
|
* Returns: - the busiest group if imbalance exists.
|
|
* - If no imbalance and user has opted for power-savings balance,
|
|
* return the least loaded group whose CPUs can be
|
|
* put to idle by rebalancing its tasks onto our group.
|
|
*/
|
|
static struct sched_group *
|
|
find_busiest_group(struct lb_env *env, int *balance)
|
|
{
|
|
struct sd_lb_stats sds;
|
|
|
|
memset(&sds, 0, sizeof(sds));
|
|
|
|
/*
|
|
* Compute the various statistics relavent for load balancing at
|
|
* this level.
|
|
*/
|
|
update_sd_lb_stats(env, balance, &sds);
|
|
|
|
/*
|
|
* this_cpu is not the appropriate cpu to perform load balancing at
|
|
* this level.
|
|
*/
|
|
if (!(*balance))
|
|
goto ret;
|
|
|
|
if ((env->idle == CPU_IDLE || env->idle == CPU_NEWLY_IDLE) &&
|
|
check_asym_packing(env, &sds))
|
|
return sds.busiest;
|
|
|
|
/* There is no busy sibling group to pull tasks from */
|
|
if (!sds.busiest || sds.busiest_nr_running == 0)
|
|
goto out_balanced;
|
|
|
|
sds.avg_load = (SCHED_POWER_SCALE * sds.total_load) / sds.total_pwr;
|
|
|
|
/*
|
|
* If the busiest group is imbalanced the below checks don't
|
|
* work because they assumes all things are equal, which typically
|
|
* isn't true due to cpus_allowed constraints and the like.
|
|
*/
|
|
if (sds.group_imb)
|
|
goto force_balance;
|
|
|
|
/* SD_BALANCE_NEWIDLE trumps SMP nice when underutilized */
|
|
if (env->idle == CPU_NEWLY_IDLE && sds.this_has_capacity &&
|
|
!sds.busiest_has_capacity)
|
|
goto force_balance;
|
|
|
|
/*
|
|
* If the local group is more busy than the selected busiest group
|
|
* don't try and pull any tasks.
|
|
*/
|
|
if (sds.this_load >= sds.max_load)
|
|
goto out_balanced;
|
|
|
|
/*
|
|
* Don't pull any tasks if this group is already above the domain
|
|
* average load.
|
|
*/
|
|
if (sds.this_load >= sds.avg_load)
|
|
goto out_balanced;
|
|
|
|
if (env->idle == CPU_IDLE) {
|
|
/*
|
|
* This cpu is idle. If the busiest group load doesn't
|
|
* have more tasks than the number of available cpu's and
|
|
* there is no imbalance between this and busiest group
|
|
* wrt to idle cpu's, it is balanced.
|
|
*/
|
|
if ((sds.this_idle_cpus <= sds.busiest_idle_cpus + 1) &&
|
|
sds.busiest_nr_running <= sds.busiest_group_weight)
|
|
goto out_balanced;
|
|
} else {
|
|
/*
|
|
* In the CPU_NEWLY_IDLE, CPU_NOT_IDLE cases, use
|
|
* imbalance_pct to be conservative.
|
|
*/
|
|
if (100 * sds.max_load <= env->sd->imbalance_pct * sds.this_load)
|
|
goto out_balanced;
|
|
}
|
|
|
|
force_balance:
|
|
/* Looks like there is an imbalance. Compute it */
|
|
calculate_imbalance(env, &sds);
|
|
return sds.busiest;
|
|
|
|
out_balanced:
|
|
ret:
|
|
env->imbalance = 0;
|
|
return NULL;
|
|
}
|
|
|
|
/*
|
|
* find_busiest_queue - find the busiest runqueue among the cpus in group.
|
|
*/
|
|
static struct rq *find_busiest_queue(struct lb_env *env,
|
|
struct sched_group *group)
|
|
{
|
|
struct rq *busiest = NULL, *rq;
|
|
unsigned long max_load = 0;
|
|
int i;
|
|
|
|
for_each_cpu(i, sched_group_cpus(group)) {
|
|
unsigned long power = power_of(i);
|
|
unsigned long capacity = DIV_ROUND_CLOSEST(power,
|
|
SCHED_POWER_SCALE);
|
|
unsigned long wl;
|
|
|
|
if (!capacity)
|
|
capacity = fix_small_capacity(env->sd, group);
|
|
|
|
if (!cpumask_test_cpu(i, env->cpus))
|
|
continue;
|
|
|
|
rq = cpu_rq(i);
|
|
wl = weighted_cpuload(i);
|
|
|
|
/*
|
|
* When comparing with imbalance, use weighted_cpuload()
|
|
* which is not scaled with the cpu power.
|
|
*/
|
|
if (capacity && rq->nr_running == 1 && wl > env->imbalance)
|
|
continue;
|
|
|
|
/*
|
|
* For the load comparisons with the other cpu's, consider
|
|
* the weighted_cpuload() scaled with the cpu power, so that
|
|
* the load can be moved away from the cpu that is potentially
|
|
* running at a lower capacity.
|
|
*/
|
|
wl = (wl * SCHED_POWER_SCALE) / power;
|
|
|
|
if (wl > max_load) {
|
|
max_load = wl;
|
|
busiest = rq;
|
|
}
|
|
}
|
|
|
|
return busiest;
|
|
}
|
|
|
|
/*
|
|
* Max backoff if we encounter pinned tasks. Pretty arbitrary value, but
|
|
* so long as it is large enough.
|
|
*/
|
|
#define MAX_PINNED_INTERVAL 512
|
|
|
|
/* Working cpumask for load_balance and load_balance_newidle. */
|
|
DEFINE_PER_CPU(cpumask_var_t, load_balance_mask);
|
|
|
|
static int need_active_balance(struct lb_env *env)
|
|
{
|
|
struct sched_domain *sd = env->sd;
|
|
|
|
if (env->idle == CPU_NEWLY_IDLE) {
|
|
|
|
/*
|
|
* ASYM_PACKING needs to force migrate tasks from busy but
|
|
* higher numbered CPUs in order to pack all tasks in the
|
|
* lowest numbered CPUs.
|
|
*/
|
|
if ((sd->flags & SD_ASYM_PACKING) && env->src_cpu > env->dst_cpu)
|
|
return 1;
|
|
}
|
|
|
|
return unlikely(sd->nr_balance_failed > sd->cache_nice_tries+2);
|
|
}
|
|
|
|
static int active_load_balance_cpu_stop(void *data);
|
|
|
|
/*
|
|
* Check this_cpu to ensure it is balanced within domain. Attempt to move
|
|
* tasks if there is an imbalance.
|
|
*/
|
|
static int load_balance(int this_cpu, struct rq *this_rq,
|
|
struct sched_domain *sd, enum cpu_idle_type idle,
|
|
int *balance)
|
|
{
|
|
int ld_moved, cur_ld_moved, active_balance = 0;
|
|
struct sched_group *group;
|
|
struct rq *busiest;
|
|
unsigned long flags;
|
|
struct cpumask *cpus = __get_cpu_var(load_balance_mask);
|
|
|
|
struct lb_env env = {
|
|
.sd = sd,
|
|
.dst_cpu = this_cpu,
|
|
.dst_rq = this_rq,
|
|
.dst_grpmask = sched_group_cpus(sd->groups),
|
|
.idle = idle,
|
|
.loop_break = sched_nr_migrate_break,
|
|
.cpus = cpus,
|
|
};
|
|
|
|
/*
|
|
* For NEWLY_IDLE load_balancing, we don't need to consider
|
|
* other cpus in our group
|
|
*/
|
|
if (idle == CPU_NEWLY_IDLE)
|
|
env.dst_grpmask = NULL;
|
|
|
|
cpumask_copy(cpus, cpu_active_mask);
|
|
|
|
schedstat_inc(sd, lb_count[idle]);
|
|
|
|
redo:
|
|
group = find_busiest_group(&env, balance);
|
|
|
|
if (*balance == 0)
|
|
goto out_balanced;
|
|
|
|
if (!group) {
|
|
schedstat_inc(sd, lb_nobusyg[idle]);
|
|
goto out_balanced;
|
|
}
|
|
|
|
busiest = find_busiest_queue(&env, group);
|
|
if (!busiest) {
|
|
schedstat_inc(sd, lb_nobusyq[idle]);
|
|
goto out_balanced;
|
|
}
|
|
|
|
BUG_ON(busiest == env.dst_rq);
|
|
|
|
schedstat_add(sd, lb_imbalance[idle], env.imbalance);
|
|
|
|
ld_moved = 0;
|
|
if (busiest->nr_running > 1) {
|
|
/*
|
|
* Attempt to move tasks. If find_busiest_group has found
|
|
* an imbalance but busiest->nr_running <= 1, the group is
|
|
* still unbalanced. ld_moved simply stays zero, so it is
|
|
* correctly treated as an imbalance.
|
|
*/
|
|
env.flags |= LBF_ALL_PINNED;
|
|
env.src_cpu = busiest->cpu;
|
|
env.src_rq = busiest;
|
|
env.loop_max = min(sysctl_sched_nr_migrate, busiest->nr_running);
|
|
|
|
update_h_load(env.src_cpu);
|
|
more_balance:
|
|
local_irq_save(flags);
|
|
double_rq_lock(env.dst_rq, busiest);
|
|
|
|
/*
|
|
* cur_ld_moved - load moved in current iteration
|
|
* ld_moved - cumulative load moved across iterations
|
|
*/
|
|
cur_ld_moved = move_tasks(&env);
|
|
ld_moved += cur_ld_moved;
|
|
double_rq_unlock(env.dst_rq, busiest);
|
|
local_irq_restore(flags);
|
|
|
|
/*
|
|
* some other cpu did the load balance for us.
|
|
*/
|
|
if (cur_ld_moved && env.dst_cpu != smp_processor_id())
|
|
resched_cpu(env.dst_cpu);
|
|
|
|
if (env.flags & LBF_NEED_BREAK) {
|
|
env.flags &= ~LBF_NEED_BREAK;
|
|
goto more_balance;
|
|
}
|
|
|
|
/*
|
|
* Revisit (affine) tasks on src_cpu that couldn't be moved to
|
|
* us and move them to an alternate dst_cpu in our sched_group
|
|
* where they can run. The upper limit on how many times we
|
|
* iterate on same src_cpu is dependent on number of cpus in our
|
|
* sched_group.
|
|
*
|
|
* This changes load balance semantics a bit on who can move
|
|
* load to a given_cpu. In addition to the given_cpu itself
|
|
* (or a ilb_cpu acting on its behalf where given_cpu is
|
|
* nohz-idle), we now have balance_cpu in a position to move
|
|
* load to given_cpu. In rare situations, this may cause
|
|
* conflicts (balance_cpu and given_cpu/ilb_cpu deciding
|
|
* _independently_ and at _same_ time to move some load to
|
|
* given_cpu) causing exceess load to be moved to given_cpu.
|
|
* This however should not happen so much in practice and
|
|
* moreover subsequent load balance cycles should correct the
|
|
* excess load moved.
|
|
*/
|
|
if ((env.flags & LBF_SOME_PINNED) && env.imbalance > 0) {
|
|
|
|
env.dst_rq = cpu_rq(env.new_dst_cpu);
|
|
env.dst_cpu = env.new_dst_cpu;
|
|
env.flags &= ~LBF_SOME_PINNED;
|
|
env.loop = 0;
|
|
env.loop_break = sched_nr_migrate_break;
|
|
|
|
/* Prevent to re-select dst_cpu via env's cpus */
|
|
cpumask_clear_cpu(env.dst_cpu, env.cpus);
|
|
|
|
/*
|
|
* Go back to "more_balance" rather than "redo" since we
|
|
* need to continue with same src_cpu.
|
|
*/
|
|
goto more_balance;
|
|
}
|
|
|
|
/* All tasks on this runqueue were pinned by CPU affinity */
|
|
if (unlikely(env.flags & LBF_ALL_PINNED)) {
|
|
cpumask_clear_cpu(cpu_of(busiest), cpus);
|
|
if (!cpumask_empty(cpus)) {
|
|
env.loop = 0;
|
|
env.loop_break = sched_nr_migrate_break;
|
|
goto redo;
|
|
}
|
|
goto out_balanced;
|
|
}
|
|
}
|
|
|
|
if (!ld_moved) {
|
|
schedstat_inc(sd, lb_failed[idle]);
|
|
/*
|
|
* Increment the failure counter only on periodic balance.
|
|
* We do not want newidle balance, which can be very
|
|
* frequent, pollute the failure counter causing
|
|
* excessive cache_hot migrations and active balances.
|
|
*/
|
|
if (idle != CPU_NEWLY_IDLE)
|
|
sd->nr_balance_failed++;
|
|
|
|
if (need_active_balance(&env)) {
|
|
raw_spin_lock_irqsave(&busiest->lock, flags);
|
|
|
|
/* don't kick the active_load_balance_cpu_stop,
|
|
* if the curr task on busiest cpu can't be
|
|
* moved to this_cpu
|
|
*/
|
|
if (!cpumask_test_cpu(this_cpu,
|
|
tsk_cpus_allowed(busiest->curr))) {
|
|
raw_spin_unlock_irqrestore(&busiest->lock,
|
|
flags);
|
|
env.flags |= LBF_ALL_PINNED;
|
|
goto out_one_pinned;
|
|
}
|
|
|
|
/*
|
|
* ->active_balance synchronizes accesses to
|
|
* ->active_balance_work. Once set, it's cleared
|
|
* only after active load balance is finished.
|
|
*/
|
|
if (!busiest->active_balance) {
|
|
busiest->active_balance = 1;
|
|
busiest->push_cpu = this_cpu;
|
|
active_balance = 1;
|
|
}
|
|
raw_spin_unlock_irqrestore(&busiest->lock, flags);
|
|
|
|
if (active_balance) {
|
|
stop_one_cpu_nowait(cpu_of(busiest),
|
|
active_load_balance_cpu_stop, busiest,
|
|
&busiest->active_balance_work);
|
|
}
|
|
|
|
/*
|
|
* We've kicked active balancing, reset the failure
|
|
* counter.
|
|
*/
|
|
sd->nr_balance_failed = sd->cache_nice_tries+1;
|
|
}
|
|
} else
|
|
sd->nr_balance_failed = 0;
|
|
|
|
if (likely(!active_balance)) {
|
|
/* We were unbalanced, so reset the balancing interval */
|
|
sd->balance_interval = sd->min_interval;
|
|
} else {
|
|
/*
|
|
* If we've begun active balancing, start to back off. This
|
|
* case may not be covered by the all_pinned logic if there
|
|
* is only 1 task on the busy runqueue (because we don't call
|
|
* move_tasks).
|
|
*/
|
|
if (sd->balance_interval < sd->max_interval)
|
|
sd->balance_interval *= 2;
|
|
}
|
|
|
|
goto out;
|
|
|
|
out_balanced:
|
|
schedstat_inc(sd, lb_balanced[idle]);
|
|
|
|
sd->nr_balance_failed = 0;
|
|
|
|
out_one_pinned:
|
|
/* tune up the balancing interval */
|
|
if (((env.flags & LBF_ALL_PINNED) &&
|
|
sd->balance_interval < MAX_PINNED_INTERVAL) ||
|
|
(sd->balance_interval < sd->max_interval))
|
|
sd->balance_interval *= 2;
|
|
|
|
ld_moved = 0;
|
|
out:
|
|
return ld_moved;
|
|
}
|
|
|
|
/*
|
|
* idle_balance is called by schedule() if this_cpu is about to become
|
|
* idle. Attempts to pull tasks from other CPUs.
|
|
*/
|
|
void idle_balance(int this_cpu, struct rq *this_rq)
|
|
{
|
|
struct sched_domain *sd;
|
|
int pulled_task = 0;
|
|
unsigned long next_balance = jiffies + HZ;
|
|
|
|
this_rq->idle_stamp = this_rq->clock;
|
|
|
|
if (this_rq->avg_idle < sysctl_sched_migration_cost)
|
|
return;
|
|
|
|
/*
|
|
* Drop the rq->lock, but keep IRQ/preempt disabled.
|
|
*/
|
|
raw_spin_unlock(&this_rq->lock);
|
|
|
|
update_blocked_averages(this_cpu);
|
|
rcu_read_lock();
|
|
for_each_domain(this_cpu, sd) {
|
|
unsigned long interval;
|
|
int balance = 1;
|
|
|
|
if (!(sd->flags & SD_LOAD_BALANCE))
|
|
continue;
|
|
|
|
if (sd->flags & SD_BALANCE_NEWIDLE) {
|
|
/* If we've pulled tasks over stop searching: */
|
|
pulled_task = load_balance(this_cpu, this_rq,
|
|
sd, CPU_NEWLY_IDLE, &balance);
|
|
}
|
|
|
|
interval = msecs_to_jiffies(sd->balance_interval);
|
|
if (time_after(next_balance, sd->last_balance + interval))
|
|
next_balance = sd->last_balance + interval;
|
|
if (pulled_task) {
|
|
this_rq->idle_stamp = 0;
|
|
break;
|
|
}
|
|
}
|
|
rcu_read_unlock();
|
|
|
|
raw_spin_lock(&this_rq->lock);
|
|
|
|
if (pulled_task || time_after(jiffies, this_rq->next_balance)) {
|
|
/*
|
|
* We are going idle. next_balance may be set based on
|
|
* a busy processor. So reset next_balance.
|
|
*/
|
|
this_rq->next_balance = next_balance;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* active_load_balance_cpu_stop is run by cpu stopper. It pushes
|
|
* running tasks off the busiest CPU onto idle CPUs. It requires at
|
|
* least 1 task to be running on each physical CPU where possible, and
|
|
* avoids physical / logical imbalances.
|
|
*/
|
|
static int active_load_balance_cpu_stop(void *data)
|
|
{
|
|
struct rq *busiest_rq = data;
|
|
int busiest_cpu = cpu_of(busiest_rq);
|
|
int target_cpu = busiest_rq->push_cpu;
|
|
struct rq *target_rq = cpu_rq(target_cpu);
|
|
struct sched_domain *sd;
|
|
|
|
raw_spin_lock_irq(&busiest_rq->lock);
|
|
|
|
/* make sure the requested cpu hasn't gone down in the meantime */
|
|
if (unlikely(busiest_cpu != smp_processor_id() ||
|
|
!busiest_rq->active_balance))
|
|
goto out_unlock;
|
|
|
|
/* Is there any task to move? */
|
|
if (busiest_rq->nr_running <= 1)
|
|
goto out_unlock;
|
|
|
|
/*
|
|
* This condition is "impossible", if it occurs
|
|
* we need to fix it. Originally reported by
|
|
* Bjorn Helgaas on a 128-cpu setup.
|
|
*/
|
|
BUG_ON(busiest_rq == target_rq);
|
|
|
|
/* move a task from busiest_rq to target_rq */
|
|
double_lock_balance(busiest_rq, target_rq);
|
|
|
|
/* Search for an sd spanning us and the target CPU. */
|
|
rcu_read_lock();
|
|
for_each_domain(target_cpu, sd) {
|
|
if ((sd->flags & SD_LOAD_BALANCE) &&
|
|
cpumask_test_cpu(busiest_cpu, sched_domain_span(sd)))
|
|
break;
|
|
}
|
|
|
|
if (likely(sd)) {
|
|
struct lb_env env = {
|
|
.sd = sd,
|
|
.dst_cpu = target_cpu,
|
|
.dst_rq = target_rq,
|
|
.src_cpu = busiest_rq->cpu,
|
|
.src_rq = busiest_rq,
|
|
.idle = CPU_IDLE,
|
|
};
|
|
|
|
schedstat_inc(sd, alb_count);
|
|
|
|
if (move_one_task(&env))
|
|
schedstat_inc(sd, alb_pushed);
|
|
else
|
|
schedstat_inc(sd, alb_failed);
|
|
}
|
|
rcu_read_unlock();
|
|
double_unlock_balance(busiest_rq, target_rq);
|
|
out_unlock:
|
|
busiest_rq->active_balance = 0;
|
|
raw_spin_unlock_irq(&busiest_rq->lock);
|
|
return 0;
|
|
}
|
|
|
|
#ifdef CONFIG_NO_HZ_COMMON
|
|
/*
|
|
* idle load balancing details
|
|
* - When one of the busy CPUs notice that there may be an idle rebalancing
|
|
* needed, they will kick the idle load balancer, which then does idle
|
|
* load balancing for all the idle CPUs.
|
|
*/
|
|
static struct {
|
|
cpumask_var_t idle_cpus_mask;
|
|
atomic_t nr_cpus;
|
|
unsigned long next_balance; /* in jiffy units */
|
|
} nohz ____cacheline_aligned;
|
|
|
|
static inline int find_new_ilb(int call_cpu)
|
|
{
|
|
int ilb = cpumask_first(nohz.idle_cpus_mask);
|
|
|
|
if (ilb < nr_cpu_ids && idle_cpu(ilb))
|
|
return ilb;
|
|
|
|
return nr_cpu_ids;
|
|
}
|
|
|
|
/*
|
|
* Kick a CPU to do the nohz balancing, if it is time for it. We pick the
|
|
* nohz_load_balancer CPU (if there is one) otherwise fallback to any idle
|
|
* CPU (if there is one).
|
|
*/
|
|
static void nohz_balancer_kick(int cpu)
|
|
{
|
|
int ilb_cpu;
|
|
|
|
nohz.next_balance++;
|
|
|
|
ilb_cpu = find_new_ilb(cpu);
|
|
|
|
if (ilb_cpu >= nr_cpu_ids)
|
|
return;
|
|
|
|
if (test_and_set_bit(NOHZ_BALANCE_KICK, nohz_flags(ilb_cpu)))
|
|
return;
|
|
/*
|
|
* Use smp_send_reschedule() instead of resched_cpu().
|
|
* This way we generate a sched IPI on the target cpu which
|
|
* is idle. And the softirq performing nohz idle load balance
|
|
* will be run before returning from the IPI.
|
|
*/
|
|
smp_send_reschedule(ilb_cpu);
|
|
return;
|
|
}
|
|
|
|
static inline void nohz_balance_exit_idle(int cpu)
|
|
{
|
|
if (unlikely(test_bit(NOHZ_TICK_STOPPED, nohz_flags(cpu)))) {
|
|
cpumask_clear_cpu(cpu, nohz.idle_cpus_mask);
|
|
atomic_dec(&nohz.nr_cpus);
|
|
clear_bit(NOHZ_TICK_STOPPED, nohz_flags(cpu));
|
|
}
|
|
}
|
|
|
|
static inline void set_cpu_sd_state_busy(void)
|
|
{
|
|
struct sched_domain *sd;
|
|
|
|
rcu_read_lock();
|
|
sd = rcu_dereference_check_sched_domain(this_rq()->sd);
|
|
|
|
if (!sd || !sd->nohz_idle)
|
|
goto unlock;
|
|
sd->nohz_idle = 0;
|
|
|
|
for (; sd; sd = sd->parent)
|
|
atomic_inc(&sd->groups->sgp->nr_busy_cpus);
|
|
unlock:
|
|
rcu_read_unlock();
|
|
}
|
|
|
|
void set_cpu_sd_state_idle(void)
|
|
{
|
|
struct sched_domain *sd;
|
|
|
|
rcu_read_lock();
|
|
sd = rcu_dereference_check_sched_domain(this_rq()->sd);
|
|
|
|
if (!sd || sd->nohz_idle)
|
|
goto unlock;
|
|
sd->nohz_idle = 1;
|
|
|
|
for (; sd; sd = sd->parent)
|
|
atomic_dec(&sd->groups->sgp->nr_busy_cpus);
|
|
unlock:
|
|
rcu_read_unlock();
|
|
}
|
|
|
|
/*
|
|
* This routine will record that the cpu is going idle with tick stopped.
|
|
* This info will be used in performing idle load balancing in the future.
|
|
*/
|
|
void nohz_balance_enter_idle(int cpu)
|
|
{
|
|
/*
|
|
* If this cpu is going down, then nothing needs to be done.
|
|
*/
|
|
if (!cpu_active(cpu))
|
|
return;
|
|
|
|
if (test_bit(NOHZ_TICK_STOPPED, nohz_flags(cpu)))
|
|
return;
|
|
|
|
cpumask_set_cpu(cpu, nohz.idle_cpus_mask);
|
|
atomic_inc(&nohz.nr_cpus);
|
|
set_bit(NOHZ_TICK_STOPPED, nohz_flags(cpu));
|
|
}
|
|
|
|
static int __cpuinit sched_ilb_notifier(struct notifier_block *nfb,
|
|
unsigned long action, void *hcpu)
|
|
{
|
|
switch (action & ~CPU_TASKS_FROZEN) {
|
|
case CPU_DYING:
|
|
nohz_balance_exit_idle(smp_processor_id());
|
|
return NOTIFY_OK;
|
|
default:
|
|
return NOTIFY_DONE;
|
|
}
|
|
}
|
|
#endif
|
|
|
|
static DEFINE_SPINLOCK(balancing);
|
|
|
|
/*
|
|
* Scale the max load_balance interval with the number of CPUs in the system.
|
|
* This trades load-balance latency on larger machines for less cross talk.
|
|
*/
|
|
void update_max_interval(void)
|
|
{
|
|
max_load_balance_interval = HZ*num_online_cpus()/10;
|
|
}
|
|
|
|
/*
|
|
* It checks each scheduling domain to see if it is due to be balanced,
|
|
* and initiates a balancing operation if so.
|
|
*
|
|
* Balancing parameters are set up in init_sched_domains.
|
|
*/
|
|
static void rebalance_domains(int cpu, enum cpu_idle_type idle)
|
|
{
|
|
int balance = 1;
|
|
struct rq *rq = cpu_rq(cpu);
|
|
unsigned long interval;
|
|
struct sched_domain *sd;
|
|
/* Earliest time when we have to do rebalance again */
|
|
unsigned long next_balance = jiffies + 60*HZ;
|
|
int update_next_balance = 0;
|
|
int need_serialize;
|
|
|
|
update_blocked_averages(cpu);
|
|
|
|
rcu_read_lock();
|
|
for_each_domain(cpu, sd) {
|
|
if (!(sd->flags & SD_LOAD_BALANCE))
|
|
continue;
|
|
|
|
interval = sd->balance_interval;
|
|
if (idle != CPU_IDLE)
|
|
interval *= sd->busy_factor;
|
|
|
|
/* scale ms to jiffies */
|
|
interval = msecs_to_jiffies(interval);
|
|
interval = clamp(interval, 1UL, max_load_balance_interval);
|
|
|
|
need_serialize = sd->flags & SD_SERIALIZE;
|
|
|
|
if (need_serialize) {
|
|
if (!spin_trylock(&balancing))
|
|
goto out;
|
|
}
|
|
|
|
if (time_after_eq(jiffies, sd->last_balance + interval)) {
|
|
if (load_balance(cpu, rq, sd, idle, &balance)) {
|
|
/*
|
|
* The LBF_SOME_PINNED logic could have changed
|
|
* env->dst_cpu, so we can't know our idle
|
|
* state even if we migrated tasks. Update it.
|
|
*/
|
|
idle = idle_cpu(cpu) ? CPU_IDLE : CPU_NOT_IDLE;
|
|
}
|
|
sd->last_balance = jiffies;
|
|
}
|
|
if (need_serialize)
|
|
spin_unlock(&balancing);
|
|
out:
|
|
if (time_after(next_balance, sd->last_balance + interval)) {
|
|
next_balance = sd->last_balance + interval;
|
|
update_next_balance = 1;
|
|
}
|
|
|
|
/*
|
|
* Stop the load balance at this level. There is another
|
|
* CPU in our sched group which is doing load balancing more
|
|
* actively.
|
|
*/
|
|
if (!balance)
|
|
break;
|
|
}
|
|
rcu_read_unlock();
|
|
|
|
/*
|
|
* next_balance will be updated only when there is a need.
|
|
* When the cpu is attached to null domain for ex, it will not be
|
|
* updated.
|
|
*/
|
|
if (likely(update_next_balance))
|
|
rq->next_balance = next_balance;
|
|
}
|
|
|
|
#ifdef CONFIG_NO_HZ_COMMON
|
|
/*
|
|
* In CONFIG_NO_HZ_COMMON case, the idle balance kickee will do the
|
|
* rebalancing for all the cpus for whom scheduler ticks are stopped.
|
|
*/
|
|
static void nohz_idle_balance(int this_cpu, enum cpu_idle_type idle)
|
|
{
|
|
struct rq *this_rq = cpu_rq(this_cpu);
|
|
struct rq *rq;
|
|
int balance_cpu;
|
|
|
|
if (idle != CPU_IDLE ||
|
|
!test_bit(NOHZ_BALANCE_KICK, nohz_flags(this_cpu)))
|
|
goto end;
|
|
|
|
for_each_cpu(balance_cpu, nohz.idle_cpus_mask) {
|
|
if (balance_cpu == this_cpu || !idle_cpu(balance_cpu))
|
|
continue;
|
|
|
|
/*
|
|
* If this cpu gets work to do, stop the load balancing
|
|
* work being done for other cpus. Next load
|
|
* balancing owner will pick it up.
|
|
*/
|
|
if (need_resched())
|
|
break;
|
|
|
|
rq = cpu_rq(balance_cpu);
|
|
|
|
raw_spin_lock_irq(&rq->lock);
|
|
update_rq_clock(rq);
|
|
update_idle_cpu_load(rq);
|
|
raw_spin_unlock_irq(&rq->lock);
|
|
|
|
rebalance_domains(balance_cpu, CPU_IDLE);
|
|
|
|
if (time_after(this_rq->next_balance, rq->next_balance))
|
|
this_rq->next_balance = rq->next_balance;
|
|
}
|
|
nohz.next_balance = this_rq->next_balance;
|
|
end:
|
|
clear_bit(NOHZ_BALANCE_KICK, nohz_flags(this_cpu));
|
|
}
|
|
|
|
/*
|
|
* Current heuristic for kicking the idle load balancer in the presence
|
|
* of an idle cpu is the system.
|
|
* - This rq has more than one task.
|
|
* - At any scheduler domain level, this cpu's scheduler group has multiple
|
|
* busy cpu's exceeding the group's power.
|
|
* - For SD_ASYM_PACKING, if the lower numbered cpu's in the scheduler
|
|
* domain span are idle.
|
|
*/
|
|
static inline int nohz_kick_needed(struct rq *rq, int cpu)
|
|
{
|
|
unsigned long now = jiffies;
|
|
struct sched_domain *sd;
|
|
|
|
if (unlikely(idle_cpu(cpu)))
|
|
return 0;
|
|
|
|
/*
|
|
* We may be recently in ticked or tickless idle mode. At the first
|
|
* busy tick after returning from idle, we will update the busy stats.
|
|
*/
|
|
set_cpu_sd_state_busy();
|
|
nohz_balance_exit_idle(cpu);
|
|
|
|
/*
|
|
* None are in tickless mode and hence no need for NOHZ idle load
|
|
* balancing.
|
|
*/
|
|
if (likely(!atomic_read(&nohz.nr_cpus)))
|
|
return 0;
|
|
|
|
if (time_before(now, nohz.next_balance))
|
|
return 0;
|
|
|
|
if (rq->nr_running >= 2)
|
|
goto need_kick;
|
|
|
|
rcu_read_lock();
|
|
for_each_domain(cpu, sd) {
|
|
struct sched_group *sg = sd->groups;
|
|
struct sched_group_power *sgp = sg->sgp;
|
|
int nr_busy = atomic_read(&sgp->nr_busy_cpus);
|
|
|
|
if (sd->flags & SD_SHARE_PKG_RESOURCES && nr_busy > 1)
|
|
goto need_kick_unlock;
|
|
|
|
if (sd->flags & SD_ASYM_PACKING && nr_busy != sg->group_weight
|
|
&& (cpumask_first_and(nohz.idle_cpus_mask,
|
|
sched_domain_span(sd)) < cpu))
|
|
goto need_kick_unlock;
|
|
|
|
if (!(sd->flags & (SD_SHARE_PKG_RESOURCES | SD_ASYM_PACKING)))
|
|
break;
|
|
}
|
|
rcu_read_unlock();
|
|
return 0;
|
|
|
|
need_kick_unlock:
|
|
rcu_read_unlock();
|
|
need_kick:
|
|
return 1;
|
|
}
|
|
#else
|
|
static void nohz_idle_balance(int this_cpu, enum cpu_idle_type idle) { }
|
|
#endif
|
|
|
|
/*
|
|
* run_rebalance_domains is triggered when needed from the scheduler tick.
|
|
* Also triggered for nohz idle balancing (with nohz_balancing_kick set).
|
|
*/
|
|
static void run_rebalance_domains(struct softirq_action *h)
|
|
{
|
|
int this_cpu = smp_processor_id();
|
|
struct rq *this_rq = cpu_rq(this_cpu);
|
|
enum cpu_idle_type idle = this_rq->idle_balance ?
|
|
CPU_IDLE : CPU_NOT_IDLE;
|
|
|
|
rebalance_domains(this_cpu, idle);
|
|
|
|
/*
|
|
* If this cpu has a pending nohz_balance_kick, then do the
|
|
* balancing on behalf of the other idle cpus whose ticks are
|
|
* stopped.
|
|
*/
|
|
nohz_idle_balance(this_cpu, idle);
|
|
}
|
|
|
|
static inline int on_null_domain(int cpu)
|
|
{
|
|
return !rcu_dereference_sched(cpu_rq(cpu)->sd);
|
|
}
|
|
|
|
/*
|
|
* Trigger the SCHED_SOFTIRQ if it is time to do periodic load balancing.
|
|
*/
|
|
void trigger_load_balance(struct rq *rq, int cpu)
|
|
{
|
|
/* Don't need to rebalance while attached to NULL domain */
|
|
if (time_after_eq(jiffies, rq->next_balance) &&
|
|
likely(!on_null_domain(cpu)))
|
|
raise_softirq(SCHED_SOFTIRQ);
|
|
#ifdef CONFIG_NO_HZ_COMMON
|
|
if (nohz_kick_needed(rq, cpu) && likely(!on_null_domain(cpu)))
|
|
nohz_balancer_kick(cpu);
|
|
#endif
|
|
}
|
|
|
|
static void rq_online_fair(struct rq *rq)
|
|
{
|
|
update_sysctl();
|
|
}
|
|
|
|
static void rq_offline_fair(struct rq *rq)
|
|
{
|
|
update_sysctl();
|
|
|
|
/* Ensure any throttled groups are reachable by pick_next_task */
|
|
unthrottle_offline_cfs_rqs(rq);
|
|
}
|
|
|
|
#endif /* CONFIG_SMP */
|
|
|
|
/*
|
|
* scheduler tick hitting a task of our scheduling class:
|
|
*/
|
|
static void task_tick_fair(struct rq *rq, struct task_struct *curr, int queued)
|
|
{
|
|
struct cfs_rq *cfs_rq;
|
|
struct sched_entity *se = &curr->se;
|
|
|
|
for_each_sched_entity(se) {
|
|
cfs_rq = cfs_rq_of(se);
|
|
entity_tick(cfs_rq, se, queued);
|
|
}
|
|
|
|
if (sched_feat_numa(NUMA))
|
|
task_tick_numa(rq, curr);
|
|
|
|
update_rq_runnable_avg(rq, 1);
|
|
}
|
|
|
|
/*
|
|
* called on fork with the child task as argument from the parent's context
|
|
* - child not yet on the tasklist
|
|
* - preemption disabled
|
|
*/
|
|
static void task_fork_fair(struct task_struct *p)
|
|
{
|
|
struct cfs_rq *cfs_rq;
|
|
struct sched_entity *se = &p->se, *curr;
|
|
int this_cpu = smp_processor_id();
|
|
struct rq *rq = this_rq();
|
|
unsigned long flags;
|
|
|
|
raw_spin_lock_irqsave(&rq->lock, flags);
|
|
|
|
update_rq_clock(rq);
|
|
|
|
cfs_rq = task_cfs_rq(current);
|
|
curr = cfs_rq->curr;
|
|
|
|
if (unlikely(task_cpu(p) != this_cpu)) {
|
|
rcu_read_lock();
|
|
__set_task_cpu(p, this_cpu);
|
|
rcu_read_unlock();
|
|
}
|
|
|
|
update_curr(cfs_rq);
|
|
|
|
if (curr)
|
|
se->vruntime = curr->vruntime;
|
|
place_entity(cfs_rq, se, 1);
|
|
|
|
if (sysctl_sched_child_runs_first && curr && entity_before(curr, se)) {
|
|
/*
|
|
* Upon rescheduling, sched_class::put_prev_task() will place
|
|
* 'current' within the tree based on its new key value.
|
|
*/
|
|
swap(curr->vruntime, se->vruntime);
|
|
resched_task(rq->curr);
|
|
}
|
|
|
|
se->vruntime -= cfs_rq->min_vruntime;
|
|
|
|
raw_spin_unlock_irqrestore(&rq->lock, flags);
|
|
}
|
|
|
|
/*
|
|
* Priority of the task has changed. Check to see if we preempt
|
|
* the current task.
|
|
*/
|
|
static void
|
|
prio_changed_fair(struct rq *rq, struct task_struct *p, int oldprio)
|
|
{
|
|
if (!p->se.on_rq)
|
|
return;
|
|
|
|
/*
|
|
* Reschedule if we are currently running on this runqueue and
|
|
* our priority decreased, or if we are not currently running on
|
|
* this runqueue and our priority is higher than the current's
|
|
*/
|
|
if (rq->curr == p) {
|
|
if (p->prio > oldprio)
|
|
resched_task(rq->curr);
|
|
} else
|
|
check_preempt_curr(rq, p, 0);
|
|
}
|
|
|
|
static void switched_from_fair(struct rq *rq, struct task_struct *p)
|
|
{
|
|
struct sched_entity *se = &p->se;
|
|
struct cfs_rq *cfs_rq = cfs_rq_of(se);
|
|
|
|
/*
|
|
* Ensure the task's vruntime is normalized, so that when its
|
|
* switched back to the fair class the enqueue_entity(.flags=0) will
|
|
* do the right thing.
|
|
*
|
|
* If it was on_rq, then the dequeue_entity(.flags=0) will already
|
|
* have normalized the vruntime, if it was !on_rq, then only when
|
|
* the task is sleeping will it still have non-normalized vruntime.
|
|
*/
|
|
if (!se->on_rq && p->state != TASK_RUNNING) {
|
|
/*
|
|
* Fix up our vruntime so that the current sleep doesn't
|
|
* cause 'unlimited' sleep bonus.
|
|
*/
|
|
place_entity(cfs_rq, se, 0);
|
|
se->vruntime -= cfs_rq->min_vruntime;
|
|
}
|
|
|
|
#if defined(CONFIG_FAIR_GROUP_SCHED) && defined(CONFIG_SMP)
|
|
/*
|
|
* Remove our load from contribution when we leave sched_fair
|
|
* and ensure we don't carry in an old decay_count if we
|
|
* switch back.
|
|
*/
|
|
if (p->se.avg.decay_count) {
|
|
struct cfs_rq *cfs_rq = cfs_rq_of(&p->se);
|
|
__synchronize_entity_decay(&p->se);
|
|
subtract_blocked_load_contrib(cfs_rq,
|
|
p->se.avg.load_avg_contrib);
|
|
}
|
|
#endif
|
|
}
|
|
|
|
/*
|
|
* We switched to the sched_fair class.
|
|
*/
|
|
static void switched_to_fair(struct rq *rq, struct task_struct *p)
|
|
{
|
|
if (!p->se.on_rq)
|
|
return;
|
|
|
|
/*
|
|
* We were most likely switched from sched_rt, so
|
|
* kick off the schedule if running, otherwise just see
|
|
* if we can still preempt the current task.
|
|
*/
|
|
if (rq->curr == p)
|
|
resched_task(rq->curr);
|
|
else
|
|
check_preempt_curr(rq, p, 0);
|
|
}
|
|
|
|
/* Account for a task changing its policy or group.
|
|
*
|
|
* This routine is mostly called to set cfs_rq->curr field when a task
|
|
* migrates between groups/classes.
|
|
*/
|
|
static void set_curr_task_fair(struct rq *rq)
|
|
{
|
|
struct sched_entity *se = &rq->curr->se;
|
|
|
|
for_each_sched_entity(se) {
|
|
struct cfs_rq *cfs_rq = cfs_rq_of(se);
|
|
|
|
set_next_entity(cfs_rq, se);
|
|
/* ensure bandwidth has been allocated on our new cfs_rq */
|
|
account_cfs_rq_runtime(cfs_rq, 0);
|
|
}
|
|
}
|
|
|
|
void init_cfs_rq(struct cfs_rq *cfs_rq)
|
|
{
|
|
cfs_rq->tasks_timeline = RB_ROOT;
|
|
cfs_rq->min_vruntime = (u64)(-(1LL << 20));
|
|
#ifndef CONFIG_64BIT
|
|
cfs_rq->min_vruntime_copy = cfs_rq->min_vruntime;
|
|
#endif
|
|
#if defined(CONFIG_FAIR_GROUP_SCHED) && defined(CONFIG_SMP)
|
|
atomic64_set(&cfs_rq->decay_counter, 1);
|
|
atomic64_set(&cfs_rq->removed_load, 0);
|
|
#endif
|
|
}
|
|
|
|
#ifdef CONFIG_FAIR_GROUP_SCHED
|
|
static void task_move_group_fair(struct task_struct *p, int on_rq)
|
|
{
|
|
struct cfs_rq *cfs_rq;
|
|
/*
|
|
* If the task was not on the rq at the time of this cgroup movement
|
|
* it must have been asleep, sleeping tasks keep their ->vruntime
|
|
* absolute on their old rq until wakeup (needed for the fair sleeper
|
|
* bonus in place_entity()).
|
|
*
|
|
* If it was on the rq, we've just 'preempted' it, which does convert
|
|
* ->vruntime to a relative base.
|
|
*
|
|
* Make sure both cases convert their relative position when migrating
|
|
* to another cgroup's rq. This does somewhat interfere with the
|
|
* fair sleeper stuff for the first placement, but who cares.
|
|
*/
|
|
/*
|
|
* When !on_rq, vruntime of the task has usually NOT been normalized.
|
|
* But there are some cases where it has already been normalized:
|
|
*
|
|
* - Moving a forked child which is waiting for being woken up by
|
|
* wake_up_new_task().
|
|
* - Moving a task which has been woken up by try_to_wake_up() and
|
|
* waiting for actually being woken up by sched_ttwu_pending().
|
|
*
|
|
* To prevent boost or penalty in the new cfs_rq caused by delta
|
|
* min_vruntime between the two cfs_rqs, we skip vruntime adjustment.
|
|
*/
|
|
if (!on_rq && (!p->se.sum_exec_runtime || p->state == TASK_WAKING))
|
|
on_rq = 1;
|
|
|
|
if (!on_rq)
|
|
p->se.vruntime -= cfs_rq_of(&p->se)->min_vruntime;
|
|
set_task_rq(p, task_cpu(p));
|
|
if (!on_rq) {
|
|
cfs_rq = cfs_rq_of(&p->se);
|
|
p->se.vruntime += cfs_rq->min_vruntime;
|
|
#ifdef CONFIG_SMP
|
|
/*
|
|
* migrate_task_rq_fair() will have removed our previous
|
|
* contribution, but we must synchronize for ongoing future
|
|
* decay.
|
|
*/
|
|
p->se.avg.decay_count = atomic64_read(&cfs_rq->decay_counter);
|
|
cfs_rq->blocked_load_avg += p->se.avg.load_avg_contrib;
|
|
#endif
|
|
}
|
|
}
|
|
|
|
void free_fair_sched_group(struct task_group *tg)
|
|
{
|
|
int i;
|
|
|
|
destroy_cfs_bandwidth(tg_cfs_bandwidth(tg));
|
|
|
|
for_each_possible_cpu(i) {
|
|
if (tg->cfs_rq)
|
|
kfree(tg->cfs_rq[i]);
|
|
if (tg->se)
|
|
kfree(tg->se[i]);
|
|
}
|
|
|
|
kfree(tg->cfs_rq);
|
|
kfree(tg->se);
|
|
}
|
|
|
|
int alloc_fair_sched_group(struct task_group *tg, struct task_group *parent)
|
|
{
|
|
struct cfs_rq *cfs_rq;
|
|
struct sched_entity *se;
|
|
int i;
|
|
|
|
tg->cfs_rq = kzalloc(sizeof(cfs_rq) * nr_cpu_ids, GFP_KERNEL);
|
|
if (!tg->cfs_rq)
|
|
goto err;
|
|
tg->se = kzalloc(sizeof(se) * nr_cpu_ids, GFP_KERNEL);
|
|
if (!tg->se)
|
|
goto err;
|
|
|
|
tg->shares = NICE_0_LOAD;
|
|
|
|
init_cfs_bandwidth(tg_cfs_bandwidth(tg));
|
|
|
|
for_each_possible_cpu(i) {
|
|
cfs_rq = kzalloc_node(sizeof(struct cfs_rq),
|
|
GFP_KERNEL, cpu_to_node(i));
|
|
if (!cfs_rq)
|
|
goto err;
|
|
|
|
se = kzalloc_node(sizeof(struct sched_entity),
|
|
GFP_KERNEL, cpu_to_node(i));
|
|
if (!se)
|
|
goto err_free_rq;
|
|
|
|
init_cfs_rq(cfs_rq);
|
|
init_tg_cfs_entry(tg, cfs_rq, se, i, parent->se[i]);
|
|
}
|
|
|
|
return 1;
|
|
|
|
err_free_rq:
|
|
kfree(cfs_rq);
|
|
err:
|
|
return 0;
|
|
}
|
|
|
|
void unregister_fair_sched_group(struct task_group *tg, int cpu)
|
|
{
|
|
struct rq *rq = cpu_rq(cpu);
|
|
unsigned long flags;
|
|
|
|
/*
|
|
* Only empty task groups can be destroyed; so we can speculatively
|
|
* check on_list without danger of it being re-added.
|
|
*/
|
|
if (!tg->cfs_rq[cpu]->on_list)
|
|
return;
|
|
|
|
raw_spin_lock_irqsave(&rq->lock, flags);
|
|
list_del_leaf_cfs_rq(tg->cfs_rq[cpu]);
|
|
raw_spin_unlock_irqrestore(&rq->lock, flags);
|
|
}
|
|
|
|
void init_tg_cfs_entry(struct task_group *tg, struct cfs_rq *cfs_rq,
|
|
struct sched_entity *se, int cpu,
|
|
struct sched_entity *parent)
|
|
{
|
|
struct rq *rq = cpu_rq(cpu);
|
|
|
|
cfs_rq->tg = tg;
|
|
cfs_rq->rq = rq;
|
|
init_cfs_rq_runtime(cfs_rq);
|
|
|
|
tg->cfs_rq[cpu] = cfs_rq;
|
|
tg->se[cpu] = se;
|
|
|
|
/* se could be NULL for root_task_group */
|
|
if (!se)
|
|
return;
|
|
|
|
if (!parent)
|
|
se->cfs_rq = &rq->cfs;
|
|
else
|
|
se->cfs_rq = parent->my_q;
|
|
|
|
se->my_q = cfs_rq;
|
|
update_load_set(&se->load, 0);
|
|
se->parent = parent;
|
|
}
|
|
|
|
static DEFINE_MUTEX(shares_mutex);
|
|
|
|
int sched_group_set_shares(struct task_group *tg, unsigned long shares)
|
|
{
|
|
int i;
|
|
unsigned long flags;
|
|
|
|
/*
|
|
* We can't change the weight of the root cgroup.
|
|
*/
|
|
if (!tg->se[0])
|
|
return -EINVAL;
|
|
|
|
shares = clamp(shares, scale_load(MIN_SHARES), scale_load(MAX_SHARES));
|
|
|
|
mutex_lock(&shares_mutex);
|
|
if (tg->shares == shares)
|
|
goto done;
|
|
|
|
tg->shares = shares;
|
|
for_each_possible_cpu(i) {
|
|
struct rq *rq = cpu_rq(i);
|
|
struct sched_entity *se;
|
|
|
|
se = tg->se[i];
|
|
/* Propagate contribution to hierarchy */
|
|
raw_spin_lock_irqsave(&rq->lock, flags);
|
|
|
|
/* Possible calls to update_curr() need rq clock */
|
|
update_rq_clock(rq);
|
|
for_each_sched_entity(se)
|
|
update_cfs_shares(group_cfs_rq(se));
|
|
raw_spin_unlock_irqrestore(&rq->lock, flags);
|
|
}
|
|
|
|
done:
|
|
mutex_unlock(&shares_mutex);
|
|
return 0;
|
|
}
|
|
#else /* CONFIG_FAIR_GROUP_SCHED */
|
|
|
|
void free_fair_sched_group(struct task_group *tg) { }
|
|
|
|
int alloc_fair_sched_group(struct task_group *tg, struct task_group *parent)
|
|
{
|
|
return 1;
|
|
}
|
|
|
|
void unregister_fair_sched_group(struct task_group *tg, int cpu) { }
|
|
|
|
#endif /* CONFIG_FAIR_GROUP_SCHED */
|
|
|
|
|
|
static unsigned int get_rr_interval_fair(struct rq *rq, struct task_struct *task)
|
|
{
|
|
struct sched_entity *se = &task->se;
|
|
unsigned int rr_interval = 0;
|
|
|
|
/*
|
|
* Time slice is 0 for SCHED_OTHER tasks that are on an otherwise
|
|
* idle runqueue:
|
|
*/
|
|
if (rq->cfs.load.weight)
|
|
rr_interval = NS_TO_JIFFIES(sched_slice(cfs_rq_of(se), se));
|
|
|
|
return rr_interval;
|
|
}
|
|
|
|
/*
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* All the scheduling class methods:
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*/
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const struct sched_class fair_sched_class = {
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.next = &idle_sched_class,
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.enqueue_task = enqueue_task_fair,
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.dequeue_task = dequeue_task_fair,
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.yield_task = yield_task_fair,
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.yield_to_task = yield_to_task_fair,
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.check_preempt_curr = check_preempt_wakeup,
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.pick_next_task = pick_next_task_fair,
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.put_prev_task = put_prev_task_fair,
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#ifdef CONFIG_SMP
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.select_task_rq = select_task_rq_fair,
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#ifdef CONFIG_FAIR_GROUP_SCHED
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.migrate_task_rq = migrate_task_rq_fair,
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#endif
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.rq_online = rq_online_fair,
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.rq_offline = rq_offline_fair,
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.task_waking = task_waking_fair,
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#endif
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.set_curr_task = set_curr_task_fair,
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.task_tick = task_tick_fair,
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.task_fork = task_fork_fair,
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.prio_changed = prio_changed_fair,
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.switched_from = switched_from_fair,
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.switched_to = switched_to_fair,
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.get_rr_interval = get_rr_interval_fair,
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#ifdef CONFIG_FAIR_GROUP_SCHED
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.task_move_group = task_move_group_fair,
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#endif
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};
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#ifdef CONFIG_SCHED_DEBUG
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void print_cfs_stats(struct seq_file *m, int cpu)
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{
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struct cfs_rq *cfs_rq;
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rcu_read_lock();
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for_each_leaf_cfs_rq(cpu_rq(cpu), cfs_rq)
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print_cfs_rq(m, cpu, cfs_rq);
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rcu_read_unlock();
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}
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#endif
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__init void init_sched_fair_class(void)
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{
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#ifdef CONFIG_SMP
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open_softirq(SCHED_SOFTIRQ, run_rebalance_domains);
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#ifdef CONFIG_NO_HZ_COMMON
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nohz.next_balance = jiffies;
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zalloc_cpumask_var(&nohz.idle_cpus_mask, GFP_NOWAIT);
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cpu_notifier(sched_ilb_notifier, 0);
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#endif
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#endif /* SMP */
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}
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