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Scheduler changes for v6.4:

Browse Source 
- Allow unprivileged PSI poll()ing
 
  - Fix performance regression introduced by mm_cid
 
  - Improve livepatch stalls by adding livepatch task switching to cond_resched(),
    this resolves livepatching busy-loop stalls with certain CPU-bound kthreads.
 
  - Improve sched_move_task() performance on autogroup configs.
 
  - On core-scheduling CPUs, avoid selecting throttled tasks to run
 
  - Misc cleanups, fixes and improvements.
 
 Signed-off-by: Ingo Molnar <mingo@kernel.org>
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Merge tag 'sched-core-2023-04-27' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip

Pull scheduler updates from Ingo Molnar:

 - Allow unprivileged PSI poll()ing

 - Fix performance regression introduced by mm_cid

 - Improve livepatch stalls by adding livepatch task switching to
   cond_resched(). This resolves livepatching busy-loop stalls with
   certain CPU-bound kthreads

 - Improve sched_move_task() performance on autogroup configs

 - On core-scheduling CPUs, avoid selecting throttled tasks to run

 - Misc cleanups, fixes and improvements

* tag 'sched-core-2023-04-27' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
  sched/clock: Fix local_clock() before sched_clock_init()
  sched/rt: Fix bad task migration for rt tasks
  sched: Fix performance regression introduced by mm_cid
  sched/core: Make sched_dynamic_mutex static
  sched/psi: Allow unprivileged polling of N*2s period
  sched/psi: Extract update_triggers side effect
  sched/psi: Rename existing poll members in preparation
  sched/psi: Rearrange polling code in preparation
  sched/fair: Fix inaccurate tally of ttwu_move_affine
  vhost: Fix livepatch timeouts in vhost_worker()
  livepatch,sched: Add livepatch task switching to cond_resched()
  livepatch: Skip task_call_func() for current task
  livepatch: Convert stack entries array to percpu
  sched: Interleave cfs bandwidth timers for improved single thread performance at low utilization
  sched/core: Reduce cost of sched_move_task when config autogroup
  sched/core: Avoid selecting the task that is throttled to run when core-sched enable
  sched/topology: Make sched_energy_mutex,update static
This commit is contained in:
Linus Torvalds 2023-04-28 14:53:30 -07:00
commit 586b222d74
21 changed files with 1430 additions and 356 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

4
Documentation/accounting/psi.rst
View File

@ -105,6 +105,10 @@ prevent overly frequent polling. Max limit is chosen as a high enough number
after which monitors are most likely not needed and psi averages can be used
instead.
Unprivileged users can also create monitors, with the only limitation that the
window size must be a multiple of 2s, in order to prevent excessive resource
usage.
When activated, psi monitor stays active for at least the duration of one
tracking window to avoid repeated activations/deactivations when system is
bouncing in and out of the stall state.

3
drivers/vhost/vhost.c
View File

@ -361,8 +361,7 @@ static int vhost_worker(void *data)
kcov_remote_start_common(worker->kcov_handle);
work->fn(work);
kcov_remote_stop();
if (need_resched())
schedule();
cond_resched();
}
}

1
include/linux/livepatch.h
View File

@ -13,6 +13,7 @@
#include <linux/ftrace.h>
#include <linux/completion.h>
#include <linux/list.h>
#include <linux/livepatch_sched.h>
#if IS_ENABLED(CONFIG_LIVEPATCH)

29
include/linux/livepatch_sched.h Normal file
View File

@ -0,0 +1,29 @@
/* SPDX-License-Identifier: GPL-2.0-or-later */
#ifndef _LINUX_LIVEPATCH_SCHED_H_
#define _LINUX_LIVEPATCH_SCHED_H_
#include <linux/jump_label.h>
#include <linux/static_call_types.h>
#ifdef CONFIG_LIVEPATCH
void __klp_sched_try_switch(void);
#if !defined(CONFIG_PREEMPT_DYNAMIC) || !defined(CONFIG_HAVE_PREEMPT_DYNAMIC_CALL)
DECLARE_STATIC_KEY_FALSE(klp_sched_try_switch_key);
static __always_inline void klp_sched_try_switch(void)
{
if (static_branch_unlikely(&klp_sched_try_switch_key))
__klp_sched_try_switch();
}
#endif /* !CONFIG_PREEMPT_DYNAMIC || !CONFIG_HAVE_PREEMPT_DYNAMIC_CALL */
#else /* !CONFIG_LIVEPATCH */
static inline void klp_sched_try_switch(void) {}
static inline void __klp_sched_try_switch(void) {}
#endif /* CONFIG_LIVEPATCH */
#endif /* _LINUX_LIVEPATCH_SCHED_H_ */

82
include/linux/mm_types.h
View File

@ -573,6 +573,13 @@ struct vm_area_struct {
struct vm_userfaultfd_ctx vm_userfaultfd_ctx;
} __randomize_layout;
#ifdef CONFIG_SCHED_MM_CID
struct mm_cid {
u64 time;
int cid;
};
#endif
struct kioctx_table;
struct mm_struct {
struct {
@ -623,15 +630,19 @@ struct mm_struct {
atomic_t mm_count;
#ifdef CONFIG_SCHED_MM_CID
/**
* @cid_lock: Protect cid bitmap updates vs lookups.
* @pcpu_cid: Per-cpu current cid.
*
* Prevent situations where updates to the cid bitmap happen
* concurrently with lookups. Those can lead to situations
* where a lookup cannot find a free bit simply because it was
* unlucky enough to load, non-atomically, bitmap words as they
* were being concurrently updated by the updaters.
* Keep track of the currently allocated mm_cid for each cpu.
* The per-cpu mm_cid values are serialized by their respective
* runqueue locks.
*/
raw_spinlock_t cid_lock;
struct mm_cid __percpu *pcpu_cid;
/*
* @mm_cid_next_scan: Next mm_cid scan (in jiffies).
*
* When the next mm_cid scan is due (in jiffies).
*/
unsigned long mm_cid_next_scan;
#endif
#ifdef CONFIG_MMU
atomic_long_t pgtables_bytes; /* size of all page tables */
@ -899,6 +910,37 @@ static inline void vma_iter_init(struct vma_iterator *vmi,
}
#ifdef CONFIG_SCHED_MM_CID
enum mm_cid_state {
MM_CID_UNSET = -1U, /* Unset state has lazy_put flag set. */
MM_CID_LAZY_PUT = (1U << 31),
};
static inline bool mm_cid_is_unset(int cid)
{
return cid == MM_CID_UNSET;
}
static inline bool mm_cid_is_lazy_put(int cid)
{
return !mm_cid_is_unset(cid) && (cid & MM_CID_LAZY_PUT);
}
static inline bool mm_cid_is_valid(int cid)
{
return !(cid & MM_CID_LAZY_PUT);
}
static inline int mm_cid_set_lazy_put(int cid)
{
return cid | MM_CID_LAZY_PUT;
}
static inline int mm_cid_clear_lazy_put(int cid)
{
return cid & ~MM_CID_LAZY_PUT;
}
/* Accessor for struct mm_struct's cidmask. */
static inline cpumask_t *mm_cidmask(struct mm_struct *mm)
{
@ -912,16 +954,40 @@ static inline cpumask_t *mm_cidmask(struct mm_struct *mm)
static inline void mm_init_cid(struct mm_struct *mm)
{
raw_spin_lock_init(&mm->cid_lock);
int i;
for_each_possible_cpu(i) {
struct mm_cid *pcpu_cid = per_cpu_ptr(mm->pcpu_cid, i);
pcpu_cid->cid = MM_CID_UNSET;
pcpu_cid->time = 0;
}
cpumask_clear(mm_cidmask(mm));
}
static inline int mm_alloc_cid(struct mm_struct *mm)
{
mm->pcpu_cid = alloc_percpu(struct mm_cid);
if (!mm->pcpu_cid)
return -ENOMEM;
mm_init_cid(mm);
return 0;
}
static inline void mm_destroy_cid(struct mm_struct *mm)
{
free_percpu(mm->pcpu_cid);
mm->pcpu_cid = NULL;
}
static inline unsigned int mm_cid_size(void)
{
return cpumask_size();
}
#else /* CONFIG_SCHED_MM_CID */
static inline void mm_init_cid(struct mm_struct *mm) { }
static inline int mm_alloc_cid(struct mm_struct *mm) { return 0; }
static inline void mm_destroy_cid(struct mm_struct *mm) { }
static inline unsigned int mm_cid_size(void)
{
return 0;

2
include/linux/psi.h
View File

@ -24,7 +24,7 @@ void psi_memstall_leave(unsigned long *flags);
int psi_show(struct seq_file *s, struct psi_group *group, enum psi_res res);
struct psi_trigger *psi_trigger_create(struct psi_group *group,
char *buf, enum psi_res res);
char *buf, enum psi_res res, struct file *file);
void psi_trigger_destroy(struct psi_trigger *t);
__poll_t psi_trigger_poll(void **trigger_ptr, struct file *file,

39
include/linux/psi_types.h
View File

@ -151,6 +151,9 @@ struct psi_trigger {
/* Deferred event(s) from previous ratelimit window */
bool pending_event;
/* Trigger type - PSI_AVGS for unprivileged, PSI_POLL for RT */
enum psi_aggregators aggregator;
};
struct psi_group {
@ -171,30 +174,34 @@ struct psi_group {
/* Aggregator work control */
struct delayed_work avgs_work;
/* Unprivileged triggers against N*PSI_FREQ windows */
struct list_head avg_triggers;
u32 avg_nr_triggers[NR_PSI_STATES - 1];
/* Total stall times and sampled pressure averages */
u64 total[NR_PSI_AGGREGATORS][NR_PSI_STATES - 1];
unsigned long avg[NR_PSI_STATES - 1][3];
/* Monitor work control */
struct task_struct __rcu *poll_task;
struct timer_list poll_timer;
wait_queue_head_t poll_wait;
atomic_t poll_wakeup;
atomic_t poll_scheduled;
/* Monitor RT polling work control */
struct task_struct __rcu *rtpoll_task;
struct timer_list rtpoll_timer;
wait_queue_head_t rtpoll_wait;
atomic_t rtpoll_wakeup;
atomic_t rtpoll_scheduled;
/* Protects data used by the monitor */
struct mutex trigger_lock;
struct mutex rtpoll_trigger_lock;
/* Configured polling triggers */
struct list_head triggers;
u32 nr_triggers[NR_PSI_STATES - 1];
u32 poll_states;
u64 poll_min_period;
/* Configured RT polling triggers */
struct list_head rtpoll_triggers;
u32 rtpoll_nr_triggers[NR_PSI_STATES - 1];
u32 rtpoll_states;
u64 rtpoll_min_period;
/* Total stall times at the start of monitor activation */
u64 polling_total[NR_PSI_STATES - 1];
u64 polling_next_update;
u64 polling_until;
/* Total stall times at the start of RT polling monitor activation */
u64 rtpoll_total[NR_PSI_STATES - 1];
u64 rtpoll_next_update;
u64 rtpoll_until;
};
#else /* CONFIG_PSI */

23
include/linux/sched.h
View File

@ -36,6 +36,7 @@
#include <linux/seqlock.h>
#include <linux/kcsan.h>
#include <linux/rv.h>
#include <linux/livepatch_sched.h>
#include <asm/kmap_size.h>
/* task_struct member predeclarations (sorted alphabetically): */
@ -1313,7 +1314,10 @@ struct task_struct {
#ifdef CONFIG_SCHED_MM_CID
int mm_cid; /* Current cid in mm */
int last_mm_cid; /* Most recent cid in mm */
int migrate_from_cpu;
int mm_cid_active; /* Whether cid bitmap is active */
struct callback_head cid_work;
#endif
struct tlbflush_unmap_batch tlb_ubc;
@ -2067,6 +2071,9 @@ extern int __cond_resched(void);
#if defined(CONFIG_PREEMPT_DYNAMIC) && defined(CONFIG_HAVE_PREEMPT_DYNAMIC_CALL)
void sched_dynamic_klp_enable(void);
void sched_dynamic_klp_disable(void);
DECLARE_STATIC_CALL(cond_resched, __cond_resched);
static __always_inline int _cond_resched(void)
@ -2075,6 +2082,7 @@ static __always_inline int _cond_resched(void)
}
#elif defined(CONFIG_PREEMPT_DYNAMIC) && defined(CONFIG_HAVE_PREEMPT_DYNAMIC_KEY)
extern int dynamic_cond_resched(void);
static __always_inline int _cond_resched(void)
@ -2082,20 +2090,25 @@ static __always_inline int _cond_resched(void)
return dynamic_cond_resched();
}
#else
#else /* !CONFIG_PREEMPTION */
static inline int _cond_resched(void)
{
klp_sched_try_switch();
return __cond_resched();
}
#endif /* CONFIG_PREEMPT_DYNAMIC */
#endif /* PREEMPT_DYNAMIC && CONFIG_HAVE_PREEMPT_DYNAMIC_CALL */
#else
#else /* CONFIG_PREEMPTION && !CONFIG_PREEMPT_DYNAMIC */
static inline int _cond_resched(void) { return 0; }
static inline int _cond_resched(void)
{
klp_sched_try_switch();
return 0;
}
#endif /* !defined(CONFIG_PREEMPTION) || defined(CONFIG_PREEMPT_DYNAMIC) */
#endif /* !CONFIG_PREEMPTION || CONFIG_PREEMPT_DYNAMIC */
#define cond_resched() ({ \
__might_resched(__FILE__, __LINE__, 0); \

5
include/linux/sched/mm.h
View File

@ -37,6 +37,11 @@ static inline void mmgrab(struct mm_struct *mm)
atomic_inc(&mm->mm_count);
}
static inline void smp_mb__after_mmgrab(void)
{
smp_mb__after_atomic();
}
extern void __mmdrop(struct mm_struct *mm);
static inline void mmdrop(struct mm_struct *mm)

2
kernel/cgroup/cgroup.c
View File

@ -3771,7 +3771,7 @@ static ssize_t pressure_write(struct kernfs_open_file *of, char *buf,
}
psi = cgroup_psi(cgrp);
new = psi_trigger_create(psi, buf, res);
new = psi_trigger_create(psi, buf, res, of->file);
if (IS_ERR(new)) {
cgroup_put(cgrp);
return PTR_ERR(new);

9
kernel/fork.c
View File

@ -924,6 +924,7 @@ void __mmdrop(struct mm_struct *mm)
check_mm(mm);
put_user_ns(mm->user_ns);
mm_pasid_drop(mm);
mm_destroy_cid(mm);
for (i = 0; i < NR_MM_COUNTERS; i++)
percpu_counter_destroy(&mm->rss_stat[i]);
@ -1188,7 +1189,9 @@ static struct task_struct *dup_task_struct(struct task_struct *orig, int node)
#ifdef CONFIG_SCHED_MM_CID
tsk->mm_cid = -1;
tsk->last_mm_cid = -1;
tsk->mm_cid_active = 0;
tsk->migrate_from_cpu = -1;
#endif
return tsk;
@ -1296,18 +1299,22 @@ static struct mm_struct *mm_init(struct mm_struct *mm, struct task_struct *p,
if (init_new_context(p, mm))
goto fail_nocontext;
if (mm_alloc_cid(mm))
goto fail_cid;
for (i = 0; i < NR_MM_COUNTERS; i++)
if (percpu_counter_init(&mm->rss_stat[i], 0, GFP_KERNEL_ACCOUNT))
goto fail_pcpu;
mm->user_ns = get_user_ns(user_ns);
lru_gen_init_mm(mm);
mm_init_cid(mm);
return mm;
fail_pcpu:
while (i > 0)
percpu_counter_destroy(&mm->rss_stat[--i]);
mm_destroy_cid(mm);
fail_cid:
destroy_context(mm);
fail_nocontext:
mm_free_pgd(mm);

1
kernel/livepatch/core.c
View File

@ -33,6 +33,7 @@
*
* - klp_ftrace_handler()
* - klp_update_patch_state()
* - __klp_sched_try_switch()
*/
DEFINE_MUTEX(klp_mutex);

122
kernel/livepatch/transition.c
View File

@ -9,11 +9,14 @@
#include <linux/cpu.h>
#include <linux/stacktrace.h>
#include <linux/static_call.h>
#include "core.h"
#include "patch.h"
#include "transition.h"
#define MAX_STACK_ENTRIES 100
DEFINE_PER_CPU(unsigned long[MAX_STACK_ENTRIES], klp_stack_entries);
#define STACK_ERR_BUF_SIZE 128
#define SIGNALS_TIMEOUT 15
@ -24,6 +27,25 @@ static int klp_target_state = KLP_UNDEFINED;
static unsigned int klp_signals_cnt;
/*
* When a livepatch is in progress, enable klp stack checking in
* cond_resched(). This helps CPU-bound kthreads get patched.
*/
#if defined(CONFIG_PREEMPT_DYNAMIC) && defined(CONFIG_HAVE_PREEMPT_DYNAMIC_CALL)
#define klp_cond_resched_enable() sched_dynamic_klp_enable()
#define klp_cond_resched_disable() sched_dynamic_klp_disable()
#else /* !CONFIG_PREEMPT_DYNAMIC || !CONFIG_HAVE_PREEMPT_DYNAMIC_CALL */
DEFINE_STATIC_KEY_FALSE(klp_sched_try_switch_key);
EXPORT_SYMBOL(klp_sched_try_switch_key);
#define klp_cond_resched_enable() static_branch_enable(&klp_sched_try_switch_key)
#define klp_cond_resched_disable() static_branch_disable(&klp_sched_try_switch_key)
#endif /* CONFIG_PREEMPT_DYNAMIC && CONFIG_HAVE_PREEMPT_DYNAMIC_CALL */
/*
* This work can be performed periodically to finish patching or unpatching any
* "straggler" tasks which failed to transition in the first attempt.
@ -172,8 +194,8 @@ void klp_update_patch_state(struct task_struct *task)
* barrier (smp_rmb) for two cases:
*
* 1) Enforce the order of the TIF_PATCH_PENDING read and the
* klp_target_state read. The corresponding write barrier is in
* klp_init_transition().
* klp_target_state read. The corresponding write barriers are in
* klp_init_transition() and klp_reverse_transition().
*
* 2) Enforce the order of the TIF_PATCH_PENDING read and a future read
* of func->transition, if klp_ftrace_handler() is called later on
@ -240,12 +262,15 @@ static int klp_check_stack_func(struct klp_func *func, unsigned long *entries,
*/
static int klp_check_stack(struct task_struct *task, const char **oldname)
{
static unsigned long entries[MAX_STACK_ENTRIES];
unsigned long *entries = this_cpu_ptr(klp_stack_entries);
struct klp_object *obj;
struct klp_func *func;
int ret, nr_entries;
ret = stack_trace_save_tsk_reliable(task, entries, ARRAY_SIZE(entries));
/* Protect 'klp_stack_entries' */
lockdep_assert_preemption_disabled();
ret = stack_trace_save_tsk_reliable(task, entries, MAX_STACK_ENTRIES);
if (ret < 0)
return -EINVAL;
nr_entries = ret;
@ -307,7 +332,11 @@ static bool klp_try_switch_task(struct task_struct *task)
* functions. If all goes well, switch the task to the target patch
* state.
*/
ret = task_call_func(task, klp_check_and_switch_task, &old_name);
if (task == current)
ret = klp_check_and_switch_task(current, &old_name);
else
ret = task_call_func(task, klp_check_and_switch_task, &old_name);
switch (ret) {
case 0: /* success */
break;
@ -334,6 +363,44 @@ static bool klp_try_switch_task(struct task_struct *task)
return !ret;
}
void __klp_sched_try_switch(void)
{
if (likely(!klp_patch_pending(current)))
return;
/*
* This function is called from cond_resched() which is called in many
* places throughout the kernel. Using the klp_mutex here might
* deadlock.
*
* Instead, disable preemption to prevent racing with other callers of
* klp_try_switch_task(). Thanks to task_call_func() they won't be
* able to switch this task while it's running.
*/
preempt_disable();
/*
* Make sure current didn't get patched between the above check and
* preempt_disable().
*/
if (unlikely(!klp_patch_pending(current)))
goto out;
/*
* Enforce the order of the TIF_PATCH_PENDING read above and the
* klp_target_state read in klp_try_switch_task(). The corresponding
* write barriers are in klp_init_transition() and
* klp_reverse_transition().
*/
smp_rmb();
klp_try_switch_task(current);
out:
preempt_enable();
}
EXPORT_SYMBOL(__klp_sched_try_switch);
/*
* Sends a fake signal to all non-kthread tasks with TIF_PATCH_PENDING set.
* Kthreads with TIF_PATCH_PENDING set are woken up.
@ -440,7 +507,8 @@ void klp_try_complete_transition(void)
return;
}
/* we're done, now cleanup the data structures */
/* Done! Now cleanup the data structures. */
klp_cond_resched_disable();
patch = klp_transition_patch;
klp_complete_transition();
@ -492,6 +560,8 @@ void klp_start_transition(void)
set_tsk_thread_flag(task, TIF_PATCH_PENDING);
}
klp_cond_resched_enable();
klp_signals_cnt = 0;
}
@ -547,8 +617,9 @@ void klp_init_transition(struct klp_patch *patch, int state)
* see a func in transition with a task->patch_state of KLP_UNDEFINED.
*
* Also enforce the order of the klp_target_state write and future
* TIF_PATCH_PENDING writes to ensure klp_update_patch_state() doesn't
* set a task->patch_state to KLP_UNDEFINED.
* TIF_PATCH_PENDING writes to ensure klp_update_patch_state() and
* __klp_sched_try_switch() don't set a task->patch_state to
* KLP_UNDEFINED.
*/
smp_wmb();
@ -584,14 +655,10 @@ void klp_reverse_transition(void)
klp_target_state == KLP_PATCHED ? "patching to unpatching" :
"unpatching to patching");
klp_transition_patch->enabled = !klp_transition_patch->enabled;
klp_target_state = !klp_target_state;
/*
* Clear all TIF_PATCH_PENDING flags to prevent races caused by
* klp_update_patch_state() running in parallel with
* klp_start_transition().
* klp_update_patch_state() or __klp_sched_try_switch() running in
* parallel with the reverse transition.
*/
read_lock(&tasklist_lock);
for_each_process_thread(g, task)
@ -601,9 +668,28 @@ void klp_reverse_transition(void)
for_each_possible_cpu(cpu)
clear_tsk_thread_flag(idle_task(cpu), TIF_PATCH_PENDING);
/* Let any remaining calls to klp_update_patch_state() complete */
/*
* Make sure all existing invocations of klp_update_patch_state() and
* __klp_sched_try_switch() see the cleared TIF_PATCH_PENDING before
* starting the reverse transition.
*/
klp_synchronize_transition();
/*
* All patching has stopped, now re-initialize the global variables to
* prepare for the reverse transition.
*/
klp_transition_patch->enabled = !klp_transition_patch->enabled;
klp_target_state = !klp_target_state;
/*
* Enforce the order of the klp_target_state write and the
* TIF_PATCH_PENDING writes in klp_start_transition() to ensure
* klp_update_patch_state() and __klp_sched_try_switch() don't set
* task->patch_state to the wrong value.
*/
smp_wmb();
klp_start_transition();
}
@ -617,9 +703,9 @@ void klp_copy_process(struct task_struct *child)
* the task flag up to date with the parent here.
*
* The operation is serialized against all klp_*_transition()
* operations by the tasklist_lock. The only exception is
* klp_update_patch_state(current), but we cannot race with
* that because we are current.
* operations by the tasklist_lock. The only exceptions are
* klp_update_patch_state(current) and __klp_sched_try_switch(), but we
* cannot race with them because we are current.
*/
if (test_tsk_thread_flag(current, TIF_PATCH_PENDING))
set_tsk_thread_flag(child, TIF_PATCH_PENDING);

3
kernel/sched/clock.c
View File

@ -300,6 +300,9 @@ noinstr u64 local_clock(void)
if (static_branch_likely(&__sched_clock_stable))
return sched_clock() + __sched_clock_offset;
if (!static_branch_likely(&sched_clock_running))
return sched_clock();
preempt_disable_notrace();
clock = sched_clock_local(this_scd());
preempt_enable_notrace();

669
kernel/sched/core.c
View File

@ -261,36 +261,51 @@ void sched_core_dequeue(struct rq *rq, struct task_struct *p, int flags)
resched_curr(rq);
}
/*
* Find left-most (aka, highest priority) task matching @cookie.
*/
static struct task_struct *sched_core_find(struct rq *rq, unsigned long cookie)
static int sched_task_is_throttled(struct task_struct *p, int cpu)
{
struct rb_node *node;
if (p->sched_class->task_is_throttled)
return p->sched_class->task_is_throttled(p, cpu);
node = rb_find_first((void *)cookie, &rq->core_tree, rb_sched_core_cmp);
/*
* The idle task always matches any cookie!
*/
if (!node)
return idle_sched_class.pick_task(rq);
return __node_2_sc(node);
return 0;
}
static struct task_struct *sched_core_next(struct task_struct *p, unsigned long cookie)
{
struct rb_node *node = &p->core_node;
int cpu = task_cpu(p);
node = rb_next(node);
do {
node = rb_next(node);
if (!node)
return NULL;
p = __node_2_sc(node);
if (p->core_cookie != cookie)
return NULL;
} while (sched_task_is_throttled(p, cpu));
return p;
}
/*
* Find left-most (aka, highest priority) and unthrottled task matching @cookie.
* If no suitable task is found, NULL will be returned.
*/
static struct task_struct *sched_core_find(struct rq *rq, unsigned long cookie)
{
struct task_struct *p;
struct rb_node *node;
node = rb_find_first((void *)cookie, &rq->core_tree, rb_sched_core_cmp);
if (!node)
return NULL;
p = container_of(node, struct task_struct, core_node);
if (p->core_cookie != cookie)
return NULL;
p = __node_2_sc(node);
if (!sched_task_is_throttled(p, rq->cpu))
return p;
return p;
return sched_core_next(p, cookie);
}
/*
@ -2087,6 +2102,8 @@ void activate_task(struct rq *rq, struct task_struct *p, int flags)
{
if (task_on_rq_migrating(p))
flags |= ENQUEUE_MIGRATED;
if (flags & ENQUEUE_MIGRATED)
sched_mm_cid_migrate_to(rq, p);
enqueue_task(rq, p, flags);
@ -3196,6 +3213,7 @@ void set_task_cpu(struct task_struct *p, unsigned int new_cpu)
p->sched_class->migrate_task_rq(p, new_cpu);
p->se.nr_migrations++;
rseq_migrate(p);
sched_mm_cid_migrate_from(p);
perf_event_task_migrate(p);
}
@ -4469,6 +4487,7 @@ static void __sched_fork(unsigned long clone_flags, struct task_struct *p)
p->wake_entry.u_flags = CSD_TYPE_TTWU;
p->migration_pending = NULL;
#endif
init_sched_mm_cid(p);
}
DEFINE_STATIC_KEY_FALSE(sched_numa_balancing);
@ -5115,7 +5134,6 @@ prepare_task_switch(struct rq *rq, struct task_struct *prev,
sched_info_switch(rq, prev, next);
perf_event_task_sched_out(prev, next);
rseq_preempt(prev);
switch_mm_cid(prev, next);
fire_sched_out_preempt_notifiers(prev, next);
kmap_local_sched_out();
prepare_task(next);
@ -5272,6 +5290,9 @@ context_switch(struct rq *rq, struct task_struct *prev,
*
* kernel -> user switch + mmdrop_lazy_tlb() active
* user -> user switch
*
* switch_mm_cid() needs to be updated if the barriers provided
* by context_switch() are modified.
*/
if (!next->mm) { // to kernel
enter_lazy_tlb(prev->active_mm, next);
@ -5301,6 +5322,9 @@ context_switch(struct rq *rq, struct task_struct *prev,
}
}
/* switch_mm_cid() requires the memory barriers above. */
switch_mm_cid(rq, prev, next);
rq->clock_update_flags &= ~(RQCF_ACT_SKIP|RQCF_REQ_SKIP);
prepare_lock_switch(rq, next, rf);
@ -5589,6 +5613,7 @@ void scheduler_tick(void)
resched_latency = cpu_resched_latency(rq);
calc_global_load_tick(rq);
sched_core_tick(rq);
task_tick_mm_cid(rq, curr);
rq_unlock(rq, &rf);
@ -6241,7 +6266,7 @@ static bool try_steal_cookie(int this, int that)
goto unlock;
p = sched_core_find(src, cookie);
if (p == src->idle)
if (!p)
goto unlock;
do {
@ -6253,6 +6278,13 @@ static bool try_steal_cookie(int this, int that)
if (p->core_occupation > dst->idle->core_occupation)
goto next;
/*
* sched_core_find() and sched_core_next() will ensure that task @p
* is not throttled now, we also need to check whether the runqueue
* of the destination CPU is being throttled.
*/
if (sched_task_is_throttled(p, this))
goto next;
deactivate_task(src, p, 0);
set_task_cpu(p, this);
@ -8508,6 +8540,7 @@ EXPORT_STATIC_CALL_TRAMP(might_resched);
static DEFINE_STATIC_KEY_FALSE(sk_dynamic_cond_resched);
int __sched dynamic_cond_resched(void)
{
klp_sched_try_switch();
if (!static_branch_unlikely(&sk_dynamic_cond_resched))
return 0;
return __cond_resched();
@ -8656,13 +8689,17 @@ int sched_dynamic_mode(const char *str)
#error "Unsupported PREEMPT_DYNAMIC mechanism"
#endif
void sched_dynamic_update(int mode)
static DEFINE_MUTEX(sched_dynamic_mutex);
static bool klp_override;
static void __sched_dynamic_update(int mode)
{
/*
* Avoid {NONE,VOLUNTARY} -> FULL transitions from ever ending up in
* the ZERO state, which is invalid.
*/
preempt_dynamic_enable(cond_resched);
if (!klp_override)
preempt_dynamic_enable(cond_resched);
preempt_dynamic_enable(might_resched);
preempt_dynamic_enable(preempt_schedule);
preempt_dynamic_enable(preempt_schedule_notrace);
@ -8670,36 +8707,79 @@ void sched_dynamic_update(int mode)
switch (mode) {
case preempt_dynamic_none:
preempt_dynamic_enable(cond_resched);
if (!klp_override)
preempt_dynamic_enable(cond_resched);
preempt_dynamic_disable(might_resched);
preempt_dynamic_disable(preempt_schedule);
preempt_dynamic_disable(preempt_schedule_notrace);
preempt_dynamic_disable(irqentry_exit_cond_resched);
pr_info("Dynamic Preempt: none\n");
if (mode != preempt_dynamic_mode)
pr_info("Dynamic Preempt: none\n");
break;
case preempt_dynamic_voluntary:
preempt_dynamic_enable(cond_resched);
if (!klp_override)
preempt_dynamic_enable(cond_resched);
preempt_dynamic_enable(might_resched);
preempt_dynamic_disable(preempt_schedule);
preempt_dynamic_disable(preempt_schedule_notrace);
preempt_dynamic_disable(irqentry_exit_cond_resched);
pr_info("Dynamic Preempt: voluntary\n");
if (mode != preempt_dynamic_mode)
pr_info("Dynamic Preempt: voluntary\n");
break;
case preempt_dynamic_full:
preempt_dynamic_disable(cond_resched);
if (!klp_override)
preempt_dynamic_disable(cond_resched);
preempt_dynamic_disable(might_resched);
preempt_dynamic_enable(preempt_schedule);
preempt_dynamic_enable(preempt_schedule_notrace);
preempt_dynamic_enable(irqentry_exit_cond_resched);
pr_info("Dynamic Preempt: full\n");
if (mode != preempt_dynamic_mode)
pr_info("Dynamic Preempt: full\n");
break;
}
preempt_dynamic_mode = mode;
}
void sched_dynamic_update(int mode)
{
mutex_lock(&sched_dynamic_mutex);
__sched_dynamic_update(mode);
mutex_unlock(&sched_dynamic_mutex);
}
#ifdef CONFIG_HAVE_PREEMPT_DYNAMIC_CALL
static int klp_cond_resched(void)
{
__klp_sched_try_switch();
return __cond_resched();
}
void sched_dynamic_klp_enable(void)
{
mutex_lock(&sched_dynamic_mutex);
klp_override = true;
static_call_update(cond_resched, klp_cond_resched);
mutex_unlock(&sched_dynamic_mutex);
}
void sched_dynamic_klp_disable(void)
{
mutex_lock(&sched_dynamic_mutex);
klp_override = false;
__sched_dynamic_update(preempt_dynamic_mode);
mutex_unlock(&sched_dynamic_mutex);
}
#endif /* CONFIG_HAVE_PREEMPT_DYNAMIC_CALL */
static int __init setup_preempt_mode(char *str)
{
int mode = sched_dynamic_mode(str);
@ -10334,7 +10414,7 @@ void sched_release_group(struct task_group *tg)
spin_unlock_irqrestore(&task_group_lock, flags);
}
static void sched_change_group(struct task_struct *tsk)
static struct task_group *sched_get_task_group(struct task_struct *tsk)
{
struct task_group *tg;
@ -10346,7 +10426,13 @@ static void sched_change_group(struct task_struct *tsk)
tg = container_of(task_css_check(tsk, cpu_cgrp_id, true),
struct task_group, css);
tg = autogroup_task_group(tsk, tg);
tsk->sched_task_group = tg;
return tg;
}
static void sched_change_group(struct task_struct *tsk, struct task_group *group)
{
tsk->sched_task_group = group;
#ifdef CONFIG_FAIR_GROUP_SCHED
if (tsk->sched_class->task_change_group)
@ -10367,10 +10453,19 @@ void sched_move_task(struct task_struct *tsk)
{
int queued, running, queue_flags =
DEQUEUE_SAVE | DEQUEUE_MOVE | DEQUEUE_NOCLOCK;
struct task_group *group;
struct rq_flags rf;
struct rq *rq;
rq = task_rq_lock(tsk, &rf);
/*
* Esp. with SCHED_AUTOGROUP enabled it is possible to get superfluous
* group changes.
*/
group = sched_get_task_group(tsk);
if (group == tsk->sched_task_group)
goto unlock;
update_rq_clock(rq);
running = task_current(rq, tsk);
@ -10381,7 +10476,7 @@ void sched_move_task(struct task_struct *tsk)
if (running)
put_prev_task(rq, tsk);
sched_change_group(tsk);
sched_change_group(tsk, group);
if (queued)
enqueue_task(rq, tsk, queue_flags);
@ -10395,6 +10490,7 @@ void sched_move_task(struct task_struct *tsk)
resched_curr(rq);
}
unlock:
task_rq_unlock(rq, tsk, &rf);
}
@ -11385,45 +11481,524 @@ void call_trace_sched_update_nr_running(struct rq *rq, int count)
}
#ifdef CONFIG_SCHED_MM_CID
void sched_mm_cid_exit_signals(struct task_struct *t)
/**
* @cid_lock: Guarantee forward-progress of cid allocation.
*
* Concurrency ID allocation within a bitmap is mostly lock-free. The cid_lock
* is only used when contention is detected by the lock-free allocation so
* forward progress can be guaranteed.
*/
DEFINE_RAW_SPINLOCK(cid_lock);
/**
* @use_cid_lock: Select cid allocation behavior: lock-free vs spinlock.
*
* When @use_cid_lock is 0, the cid allocation is lock-free. When contention is
* detected, it is set to 1 to ensure that all newly coming allocations are
* serialized by @cid_lock until the allocation which detected contention
* completes and sets @use_cid_lock back to 0. This guarantees forward progress
* of a cid allocation.
*/
int use_cid_lock;
/*
* mm_cid remote-clear implements a lock-free algorithm to clear per-mm/cpu cid
* concurrently with respect to the execution of the source runqueue context
* switch.
*
* There is one basic properties we want to guarantee here:
*
* (1) Remote-clear should _never_ mark a per-cpu cid UNSET when it is actively
* used by a task. That would lead to concurrent allocation of the cid and
* userspace corruption.
*
* Provide this guarantee by introducing a Dekker memory ordering to guarantee
* that a pair of loads observe at least one of a pair of stores, which can be
* shown as:
*
* X = Y = 0
*
* w[X]=1 w[Y]=1
* MB MB
* r[Y]=y r[X]=x
*
* Which guarantees that x==0 && y==0 is impossible. But rather than using
* values 0 and 1, this algorithm cares about specific state transitions of the
* runqueue current task (as updated by the scheduler context switch), and the
* per-mm/cpu cid value.
*
* Let's introduce task (Y) which has task->mm == mm and task (N) which has
* task->mm != mm for the rest of the discussion. There are two scheduler state
* transitions on context switch we care about:
*
* (TSA) Store to rq->curr with transition from (N) to (Y)
*
* (TSB) Store to rq->curr with transition from (Y) to (N)
*
* On the remote-clear side, there is one transition we care about:
*
* (TMA) cmpxchg to *pcpu_cid to set the LAZY flag
*
* There is also a transition to UNSET state which can be performed from all
* sides (scheduler, remote-clear). It is always performed with a cmpxchg which
* guarantees that only a single thread will succeed:
*
* (TMB) cmpxchg to *pcpu_cid to mark UNSET
*
* Just to be clear, what we do _not_ want to happen is a transition to UNSET
* when a thread is actively using the cid (property (1)).
*
* Let's looks at the relevant combinations of TSA/TSB, and TMA transitions.
*
* Scenario A) (TSA)+(TMA) (from next task perspective)
*
* CPU0 CPU1
*
* Context switch CS-1 Remote-clear
* - store to rq->curr: (N)->(Y) (TSA) - cmpxchg to *pcpu_id to LAZY (TMA)
* (implied barrier after cmpxchg)
* - switch_mm_cid()
* - memory barrier (see switch_mm_cid()
* comment explaining how this barrier
* is combined with other scheduler
* barriers)
* - mm_cid_get (next)
* - READ_ONCE(*pcpu_cid) - rcu_dereference(src_rq->curr)
*
* This Dekker ensures that either task (Y) is observed by the
* rcu_dereference() or the LAZY flag is observed by READ_ONCE(), or both are
* observed.
*
* If task (Y) store is observed by rcu_dereference(), it means that there is
* still an active task on the cpu. Remote-clear will therefore not transition
* to UNSET, which fulfills property (1).
*
* If task (Y) is not observed, but the lazy flag is observed by READ_ONCE(),
* it will move its state to UNSET, which clears the percpu cid perhaps
* uselessly (which is not an issue for correctness). Because task (Y) is not
* observed, CPU1 can move ahead to set the state to UNSET. Because moving
* state to UNSET is done with a cmpxchg expecting that the old state has the
* LAZY flag set, only one thread will successfully UNSET.
*
* If both states (LAZY flag and task (Y)) are observed, the thread on CPU0
* will observe the LAZY flag and transition to UNSET (perhaps uselessly), and
* CPU1 will observe task (Y) and do nothing more, which is fine.
*
* What we are effectively preventing with this Dekker is a scenario where
* neither LAZY flag nor store (Y) are observed, which would fail property (1)
* because this would UNSET a cid which is actively used.
*/
void sched_mm_cid_migrate_from(struct task_struct *t)
{
t->migrate_from_cpu = task_cpu(t);
}
static
int __sched_mm_cid_migrate_from_fetch_cid(struct rq *src_rq,
struct task_struct *t,
struct mm_cid *src_pcpu_cid)
{
struct mm_struct *mm = t->mm;
unsigned long flags;
struct task_struct *src_task;
int src_cid, last_mm_cid;
if (!mm)
return -1;
last_mm_cid = t->last_mm_cid;
/*
* If the migrated task has no last cid, or if the current
* task on src rq uses the cid, it means the source cid does not need
* to be moved to the destination cpu.
*/
if (last_mm_cid == -1)
return -1;
src_cid = READ_ONCE(src_pcpu_cid->cid);
if (!mm_cid_is_valid(src_cid) || last_mm_cid != src_cid)
return -1;
/*
* If we observe an active task using the mm on this rq, it means we
* are not the last task to be migrated from this cpu for this mm, so
* there is no need to move src_cid to the destination cpu.
*/
rcu_read_lock();
src_task = rcu_dereference(src_rq->curr);
if (READ_ONCE(src_task->mm_cid_active) && src_task->mm == mm) {
rcu_read_unlock();
t->last_mm_cid = -1;
return -1;
}
rcu_read_unlock();
return src_cid;
}
static
int __sched_mm_cid_migrate_from_try_steal_cid(struct rq *src_rq,
struct task_struct *t,
struct mm_cid *src_pcpu_cid,
int src_cid)
{
struct task_struct *src_task;
struct mm_struct *mm = t->mm;
int lazy_cid;
if (src_cid == -1)
return -1;
/*
* Attempt to clear the source cpu cid to move it to the destination
* cpu.
*/
lazy_cid = mm_cid_set_lazy_put(src_cid);
if (!try_cmpxchg(&src_pcpu_cid->cid, &src_cid, lazy_cid))
return -1;
/*
* The implicit barrier after cmpxchg per-mm/cpu cid before loading
* rq->curr->mm matches the scheduler barrier in context_switch()
* between store to rq->curr and load of prev and next task's
* per-mm/cpu cid.
*
* The implicit barrier after cmpxchg per-mm/cpu cid before loading
* rq->curr->mm_cid_active matches the barrier in
* sched_mm_cid_exit_signals(), sched_mm_cid_before_execve(), and
* sched_mm_cid_after_execve() between store to t->mm_cid_active and
* load of per-mm/cpu cid.
*/
/*
* If we observe an active task using the mm on this rq after setting
* the lazy-put flag, this task will be responsible for transitioning
* from lazy-put flag set to MM_CID_UNSET.
*/
rcu_read_lock();
src_task = rcu_dereference(src_rq->curr);
if (READ_ONCE(src_task->mm_cid_active) && src_task->mm == mm) {
rcu_read_unlock();
/*
* We observed an active task for this mm, there is therefore
* no point in moving this cid to the destination cpu.
*/
t->last_mm_cid = -1;
return -1;
}
rcu_read_unlock();
/*
* The src_cid is unused, so it can be unset.
*/
if (!try_cmpxchg(&src_pcpu_cid->cid, &lazy_cid, MM_CID_UNSET))
return -1;
return src_cid;
}
/*
* Migration to dst cpu. Called with dst_rq lock held.
* Interrupts are disabled, which keeps the window of cid ownership without the
* source rq lock held small.
*/
void sched_mm_cid_migrate_to(struct rq *dst_rq, struct task_struct *t)
{
struct mm_cid *src_pcpu_cid, *dst_pcpu_cid;
struct mm_struct *mm = t->mm;
int src_cid, dst_cid, src_cpu;
struct rq *src_rq;
lockdep_assert_rq_held(dst_rq);
if (!mm)
return;
src_cpu = t->migrate_from_cpu;
if (src_cpu == -1) {
t->last_mm_cid = -1;
return;
}
/*
* Move the src cid if the dst cid is unset. This keeps id
* allocation closest to 0 in cases where few threads migrate around
* many cpus.
*
* If destination cid is already set, we may have to just clear
* the src cid to ensure compactness in frequent migrations
* scenarios.
*
* It is not useful to clear the src cid when the number of threads is
* greater or equal to the number of allowed cpus, because user-space
* can expect that the number of allowed cids can reach the number of
* allowed cpus.
*/
dst_pcpu_cid = per_cpu_ptr(mm->pcpu_cid, cpu_of(dst_rq));
dst_cid = READ_ONCE(dst_pcpu_cid->cid);
if (!mm_cid_is_unset(dst_cid) &&
atomic_read(&mm->mm_users) >= t->nr_cpus_allowed)
return;
src_pcpu_cid = per_cpu_ptr(mm->pcpu_cid, src_cpu);
src_rq = cpu_rq(src_cpu);
src_cid = __sched_mm_cid_migrate_from_fetch_cid(src_rq, t, src_pcpu_cid);
if (src_cid == -1)
return;
src_cid = __sched_mm_cid_migrate_from_try_steal_cid(src_rq, t, src_pcpu_cid,
src_cid);
if (src_cid == -1)
return;
if (!mm_cid_is_unset(dst_cid)) {
__mm_cid_put(mm, src_cid);
return;
}
/* Move src_cid to dst cpu. */
mm_cid_snapshot_time(dst_rq, mm);
WRITE_ONCE(dst_pcpu_cid->cid, src_cid);
}
static void sched_mm_cid_remote_clear(struct mm_struct *mm, struct mm_cid *pcpu_cid,
int cpu)
{
struct rq *rq = cpu_rq(cpu);
struct task_struct *t;
unsigned long flags;
int cid, lazy_cid;
cid = READ_ONCE(pcpu_cid->cid);
if (!mm_cid_is_valid(cid))
return;
/*
* Clear the cpu cid if it is set to keep cid allocation compact. If
* there happens to be other tasks left on the source cpu using this
* mm, the next task using this mm will reallocate its cid on context
* switch.
*/
lazy_cid = mm_cid_set_lazy_put(cid);
if (!try_cmpxchg(&pcpu_cid->cid, &cid, lazy_cid))
return;
/*
* The implicit barrier after cmpxchg per-mm/cpu cid before loading
* rq->curr->mm matches the scheduler barrier in context_switch()
* between store to rq->curr and load of prev and next task's
* per-mm/cpu cid.
*
* The implicit barrier after cmpxchg per-mm/cpu cid before loading
* rq->curr->mm_cid_active matches the barrier in
* sched_mm_cid_exit_signals(), sched_mm_cid_before_execve(), and
* sched_mm_cid_after_execve() between store to t->mm_cid_active and
* load of per-mm/cpu cid.
*/
/*
* If we observe an active task using the mm on this rq after setting
* the lazy-put flag, that task will be responsible for transitioning
* from lazy-put flag set to MM_CID_UNSET.
*/
rcu_read_lock();
t = rcu_dereference(rq->curr);
if (READ_ONCE(t->mm_cid_active) && t->mm == mm) {
rcu_read_unlock();
return;
}
rcu_read_unlock();
/*
* The cid is unused, so it can be unset.
* Disable interrupts to keep the window of cid ownership without rq
* lock small.
*/
local_irq_save(flags);
mm_cid_put(mm, t->mm_cid);
t->mm_cid = -1;
t->mm_cid_active = 0;
if (try_cmpxchg(&pcpu_cid->cid, &lazy_cid, MM_CID_UNSET))
__mm_cid_put(mm, cid);
local_irq_restore(flags);
}
static void sched_mm_cid_remote_clear_old(struct mm_struct *mm, int cpu)
{
struct rq *rq = cpu_rq(cpu);
struct mm_cid *pcpu_cid;
struct task_struct *curr;
u64 rq_clock;
/*
* rq->clock load is racy on 32-bit but one spurious clear once in a
* while is irrelevant.
*/
rq_clock = READ_ONCE(rq->clock);
pcpu_cid = per_cpu_ptr(mm->pcpu_cid, cpu);
/*
* In order to take care of infrequently scheduled tasks, bump the time
* snapshot associated with this cid if an active task using the mm is
* observed on this rq.
*/
rcu_read_lock();
curr = rcu_dereference(rq->curr);
if (READ_ONCE(curr->mm_cid_active) && curr->mm == mm) {
WRITE_ONCE(pcpu_cid->time, rq_clock);
rcu_read_unlock();
return;
}
rcu_read_unlock();
if (rq_clock < pcpu_cid->time + SCHED_MM_CID_PERIOD_NS)
return;
sched_mm_cid_remote_clear(mm, pcpu_cid, cpu);
}
static void sched_mm_cid_remote_clear_weight(struct mm_struct *mm, int cpu,
int weight)
{
struct mm_cid *pcpu_cid;
int cid;
pcpu_cid = per_cpu_ptr(mm->pcpu_cid, cpu);
cid = READ_ONCE(pcpu_cid->cid);
if (!mm_cid_is_valid(cid) || cid < weight)
return;
sched_mm_cid_remote_clear(mm, pcpu_cid, cpu);
}
static void task_mm_cid_work(struct callback_head *work)
{
unsigned long now = jiffies, old_scan, next_scan;
struct task_struct *t = current;
struct cpumask *cidmask;
struct mm_struct *mm;
int weight, cpu;
SCHED_WARN_ON(t != container_of(work, struct task_struct, cid_work));
work->next = work; /* Prevent double-add */
if (t->flags & PF_EXITING)
return;
mm = t->mm;
if (!mm)
return;
old_scan = READ_ONCE(mm->mm_cid_next_scan);
next_scan = now + msecs_to_jiffies(MM_CID_SCAN_DELAY);
if (!old_scan) {
unsigned long res;
res = cmpxchg(&mm->mm_cid_next_scan, old_scan, next_scan);
if (res != old_scan)
old_scan = res;
else
old_scan = next_scan;
}
if (time_before(now, old_scan))
return;
if (!try_cmpxchg(&mm->mm_cid_next_scan, &old_scan, next_scan))
return;
cidmask = mm_cidmask(mm);
/* Clear cids that were not recently used. */
for_each_possible_cpu(cpu)
sched_mm_cid_remote_clear_old(mm, cpu);
weight = cpumask_weight(cidmask);
/*
* Clear cids that are greater or equal to the cidmask weight to
* recompact it.
*/
for_each_possible_cpu(cpu)
sched_mm_cid_remote_clear_weight(mm, cpu, weight);
}
void init_sched_mm_cid(struct task_struct *t)
{
struct mm_struct *mm = t->mm;
int mm_users = 0;
if (mm) {
mm_users = atomic_read(&mm->mm_users);
if (mm_users == 1)
mm->mm_cid_next_scan = jiffies + msecs_to_jiffies(MM_CID_SCAN_DELAY);
}
t->cid_work.next = &t->cid_work; /* Protect against double add */
init_task_work(&t->cid_work, task_mm_cid_work);
}
void task_tick_mm_cid(struct rq *rq, struct task_struct *curr)
{
struct callback_head *work = &curr->cid_work;
unsigned long now = jiffies;
if (!curr->mm || (curr->flags & (PF_EXITING | PF_KTHREAD)) ||
work->next != work)
return;
if (time_before(now, READ_ONCE(curr->mm->mm_cid_next_scan)))
return;
task_work_add(curr, work, TWA_RESUME);
}
void sched_mm_cid_exit_signals(struct task_struct *t)
{
struct mm_struct *mm = t->mm;
struct rq_flags rf;
struct rq *rq;
if (!mm)
return;
preempt_disable();
rq = this_rq();
rq_lock_irqsave(rq, &rf);
preempt_enable_no_resched(); /* holding spinlock */
WRITE_ONCE(t->mm_cid_active, 0);
/*
* Store t->mm_cid_active before loading per-mm/cpu cid.
* Matches barrier in sched_mm_cid_remote_clear_old().
*/
smp_mb();
mm_cid_put(mm);
t->last_mm_cid = t->mm_cid = -1;
rq_unlock_irqrestore(rq, &rf);
}
void sched_mm_cid_before_execve(struct task_struct *t)
{
struct mm_struct *mm = t->mm;
unsigned long flags;
struct rq_flags rf;
struct rq *rq;
if (!mm)
return;
local_irq_save(flags);
mm_cid_put(mm, t->mm_cid);
t->mm_cid = -1;
t->mm_cid_active = 0;
local_irq_restore(flags);
preempt_disable();
rq = this_rq();
rq_lock_irqsave(rq, &rf);
preempt_enable_no_resched(); /* holding spinlock */
WRITE_ONCE(t->mm_cid_active, 0);
/*
* Store t->mm_cid_active before loading per-mm/cpu cid.
* Matches barrier in sched_mm_cid_remote_clear_old().
*/
smp_mb();
mm_cid_put(mm);
t->last_mm_cid = t->mm_cid = -1;
rq_unlock_irqrestore(rq, &rf);
}
void sched_mm_cid_after_execve(struct task_struct *t)
{
struct mm_struct *mm = t->mm;
unsigned long flags;
struct rq_flags rf;
struct rq *rq;
if (!mm)
return;
local_irq_save(flags);
t->mm_cid = mm_cid_get(mm);
t->mm_cid_active = 1;
local_irq_restore(flags);
preempt_disable();
rq = this_rq();
rq_lock_irqsave(rq, &rf);
preempt_enable_no_resched(); /* holding spinlock */
WRITE_ONCE(t->mm_cid_active, 1);
/*
* Store t->mm_cid_active before loading per-mm/cpu cid.
* Matches barrier in sched_mm_cid_remote_clear_old().
*/
smp_mb();
t->last_mm_cid = t->mm_cid = mm_cid_get(rq, mm);
rq_unlock_irqrestore(rq, &rf);
rseq_set_notify_resume(t);
}

11
kernel/sched/deadline.c
View File

@ -2246,6 +2246,7 @@ static struct rq *find_lock_later_rq(struct task_struct *task, struct rq *rq)
!cpumask_test_cpu(later_rq->cpu, &task->cpus_mask) ||
task_on_cpu(rq, task) ||
!dl_task(task) ||
is_migration_disabled(task) ||
!task_on_rq_queued(task))) {
double_unlock_balance(rq, later_rq);
later_rq = NULL;
@ -2704,6 +2705,13 @@ static void prio_changed_dl(struct rq *rq, struct task_struct *p,
#endif
}
#ifdef CONFIG_SCHED_CORE
static int task_is_throttled_dl(struct task_struct *p, int cpu)
{
return p->dl.dl_throttled;
}
#endif
DEFINE_SCHED_CLASS(dl) = {
.enqueue_task = enqueue_task_dl,
@ -2736,6 +2744,9 @@ DEFINE_SCHED_CLASS(dl) = {
.switched_to = switched_to_dl,
.update_curr = update_curr_dl,
#ifdef CONFIG_SCHED_CORE
.task_is_throttled = task_is_throttled_dl,
#endif
};
/* Used for dl_bw check and update, used under sched_rt_handler()::mutex */

22
kernel/sched/fair.c
View File

@ -6016,6 +6016,10 @@ void init_cfs_bandwidth(struct cfs_bandwidth *cfs_b)
INIT_LIST_HEAD(&cfs_b->throttled_cfs_rq);
hrtimer_init(&cfs_b->period_timer, CLOCK_MONOTONIC, HRTIMER_MODE_ABS_PINNED);
cfs_b->period_timer.function = sched_cfs_period_timer;
/* Add a random offset so that timers interleave */
hrtimer_set_expires(&cfs_b->period_timer,
get_random_u32_below(cfs_b->period));
hrtimer_init(&cfs_b->slack_timer, CLOCK_MONOTONIC, HRTIMER_MODE_REL);
cfs_b->slack_timer.function = sched_cfs_slack_timer;
cfs_b->slack_started = false;
@ -6671,7 +6675,7 @@ static int wake_affine(struct sched_domain *sd, struct task_struct *p,
target = wake_affine_weight(sd, p, this_cpu, prev_cpu, sync);
schedstat_inc(p->stats.nr_wakeups_affine_attempts);
if (target == nr_cpumask_bits)
if (target != this_cpu)
return prev_cpu;
schedstat_inc(sd->ttwu_move_affine);
@ -12033,6 +12037,18 @@ bool cfs_prio_less(const struct task_struct *a, const struct task_struct *b,
return delta > 0;
}
static int task_is_throttled_fair(struct task_struct *p, int cpu)
{
struct cfs_rq *cfs_rq;
#ifdef CONFIG_FAIR_GROUP_SCHED
cfs_rq = task_group(p)->cfs_rq[cpu];
#else
cfs_rq = &cpu_rq(cpu)->cfs;
#endif
return throttled_hierarchy(cfs_rq);
}
#else
static inline void task_tick_core(struct rq *rq, struct task_struct *curr) {}
#endif
@ -12659,6 +12675,10 @@ DEFINE_SCHED_CLASS(fair) = {
.task_change_group = task_change_group_fair,
#endif
#ifdef CONFIG_SCHED_CORE
.task_is_throttled = task_is_throttled_fair,
#endif
#ifdef CONFIG_UCLAMP_TASK
.uclamp_enabled = 1,
#endif

489
kernel/sched/psi.c
View File

@ -186,17 +186,22 @@ static void group_init(struct psi_group *group)
seqcount_init(&per_cpu_ptr(group->pcpu, cpu)->seq);
group->avg_last_update = sched_clock();
group->avg_next_update = group->avg_last_update + psi_period;
INIT_DELAYED_WORK(&group->avgs_work, psi_avgs_work);
mutex_init(&group->avgs_lock);
/* Init trigger-related members */
atomic_set(&group->poll_scheduled, 0);
mutex_init(&group->trigger_lock);
INIT_LIST_HEAD(&group->triggers);
group->poll_min_period = U32_MAX;
group->polling_next_update = ULLONG_MAX;
init_waitqueue_head(&group->poll_wait);
timer_setup(&group->poll_timer, poll_timer_fn, 0);
rcu_assign_pointer(group->poll_task, NULL);
/* Init avg trigger-related members */
INIT_LIST_HEAD(&group->avg_triggers);
memset(group->avg_nr_triggers, 0, sizeof(group->avg_nr_triggers));
INIT_DELAYED_WORK(&group->avgs_work, psi_avgs_work);
/* Init rtpoll trigger-related members */
atomic_set(&group->rtpoll_scheduled, 0);
mutex_init(&group->rtpoll_trigger_lock);
INIT_LIST_HEAD(&group->rtpoll_triggers);
group->rtpoll_min_period = U32_MAX;
group->rtpoll_next_update = ULLONG_MAX;
init_waitqueue_head(&group->rtpoll_wait);
timer_setup(&group->rtpoll_timer, poll_timer_fn, 0);
rcu_assign_pointer(group->rtpoll_task, NULL);
}
void __init psi_init(void)
@ -384,6 +389,121 @@ static void collect_percpu_times(struct psi_group *group,
*pchanged_states = changed_states;
}
/* Trigger tracking window manipulations */
static void window_reset(struct psi_window *win, u64 now, u64 value,
u64 prev_growth)
{
win->start_time = now;
win->start_value = value;
win->prev_growth = prev_growth;
}
/*
* PSI growth tracking window update and growth calculation routine.
*
* This approximates a sliding tracking window by interpolating
* partially elapsed windows using historical growth data from the
* previous intervals. This minimizes memory requirements (by not storing
* all the intermediate values in the previous window) and simplifies
* the calculations. It works well because PSI signal changes only in
* positive direction and over relatively small window sizes the growth
* is close to linear.
*/
static u64 window_update(struct psi_window *win, u64 now, u64 value)
{
u64 elapsed;
u64 growth;
elapsed = now - win->start_time;
growth = value - win->start_value;
/*
* After each tracking window passes win->start_value and
* win->start_time get reset and win->prev_growth stores
* the average per-window growth of the previous window.
* win->prev_growth is then used to interpolate additional
* growth from the previous window assuming it was linear.
*/
if (elapsed > win->size)
window_reset(win, now, value, growth);
else {
u32 remaining;
remaining = win->size - elapsed;
growth += div64_u64(win->prev_growth * remaining, win->size);
}
return growth;
}
static u64 update_triggers(struct psi_group *group, u64 now, bool *update_total,
enum psi_aggregators aggregator)
{
struct psi_trigger *t;
u64 *total = group->total[aggregator];
struct list_head *triggers;
u64 *aggregator_total;
*update_total = false;
if (aggregator == PSI_AVGS) {
triggers = &group->avg_triggers;
aggregator_total = group->avg_total;
} else {
triggers = &group->rtpoll_triggers;
aggregator_total = group->rtpoll_total;
}
/*
* On subsequent updates, calculate growth deltas and let
* watchers know when their specified thresholds are exceeded.
*/
list_for_each_entry(t, triggers, node) {
u64 growth;
bool new_stall;
new_stall = aggregator_total[t->state] != total[t->state];
/* Check for stall activity or a previous threshold breach */
if (!new_stall && !t->pending_event)
continue;
/*
* Check for new stall activity, as well as deferred
* events that occurred in the last window after the
* trigger had already fired (we want to ratelimit
* events without dropping any).
*/
if (new_stall) {
/*
* Multiple triggers might be looking at the same state,
* remember to update group->polling_total[] once we've
* been through all of them. Also remember to extend the
* polling time if we see new stall activity.
*/
*update_total = true;
/* Calculate growth since last update */
growth = window_update(&t->win, now, total[t->state]);
if (!t->pending_event) {
if (growth < t->threshold)
continue;
t->pending_event = true;
}
}
/* Limit event signaling to once per window */
if (now < t->last_event_time + t->win.size)
continue;
/* Generate an event */
if (cmpxchg(&t->event, 0, 1) == 0)
wake_up_interruptible(&t->event_wait);
t->last_event_time = now;
/* Reset threshold breach flag once event got generated */
t->pending_event = false;
}
return now + group->rtpoll_min_period;
}
static u64 update_averages(struct psi_group *group, u64 now)
{
unsigned long missed_periods = 0;
@ -442,6 +562,7 @@ static void psi_avgs_work(struct work_struct *work)
struct delayed_work *dwork;
struct psi_group *group;
u32 changed_states;
bool update_total;
u64 now;
dwork = to_delayed_work(work);
@ -459,8 +580,10 @@ static void psi_avgs_work(struct work_struct *work)
* Once restarted, we'll catch up the running averages in one
* go - see calc_avgs() and missed_periods.
*/
if (now >= group->avg_next_update)
if (now >= group->avg_next_update) {
update_triggers(group, now, &update_total, PSI_AVGS);
group->avg_next_update = update_averages(group, now);
}
if (changed_states & PSI_STATE_RESCHEDULE) {
schedule_delayed_work(dwork, nsecs_to_jiffies(
@ -470,165 +593,58 @@ static void psi_avgs_work(struct work_struct *work)
mutex_unlock(&group->avgs_lock);
}
/* Trigger tracking window manipulations */
static void window_reset(struct psi_window *win, u64 now, u64 value,
u64 prev_growth)
{
win->start_time = now;
win->start_value = value;
win->prev_growth = prev_growth;
}
/*
* PSI growth tracking window update and growth calculation routine.
*
* This approximates a sliding tracking window by interpolating
* partially elapsed windows using historical growth data from the
* previous intervals. This minimizes memory requirements (by not storing
* all the intermediate values in the previous window) and simplifies
* the calculations. It works well because PSI signal changes only in
* positive direction and over relatively small window sizes the growth
* is close to linear.
*/
static u64 window_update(struct psi_window *win, u64 now, u64 value)
{
u64 elapsed;
u64 growth;
elapsed = now - win->start_time;
growth = value - win->start_value;
/*
* After each tracking window passes win->start_value and
* win->start_time get reset and win->prev_growth stores
* the average per-window growth of the previous window.
* win->prev_growth is then used to interpolate additional
* growth from the previous window assuming it was linear.
*/
if (elapsed > win->size)
window_reset(win, now, value, growth);
else {
u32 remaining;
remaining = win->size - elapsed;
growth += div64_u64(win->prev_growth * remaining, win->size);
}
return growth;
}
static void init_triggers(struct psi_group *group, u64 now)
static void init_rtpoll_triggers(struct psi_group *group, u64 now)
{
struct psi_trigger *t;
list_for_each_entry(t, &group->triggers, node)
list_for_each_entry(t, &group->rtpoll_triggers, node)
window_reset(&t->win, now,
group->total[PSI_POLL][t->state], 0);
memcpy(group->polling_total, group->total[PSI_POLL],
sizeof(group->polling_total));
group->polling_next_update = now + group->poll_min_period;
}
static u64 update_triggers(struct psi_group *group, u64 now)
{
struct psi_trigger *t;
bool update_total = false;
u64 *total = group->total[PSI_POLL];
/*
* On subsequent updates, calculate growth deltas and let
* watchers know when their specified thresholds are exceeded.
*/
list_for_each_entry(t, &group->triggers, node) {
u64 growth;
bool new_stall;
new_stall = group->polling_total[t->state] != total[t->state];
/* Check for stall activity or a previous threshold breach */
if (!new_stall && !t->pending_event)
continue;
/*
* Check for new stall activity, as well as deferred
* events that occurred in the last window after the
* trigger had already fired (we want to ratelimit
* events without dropping any).
*/
if (new_stall) {
/*
* Multiple triggers might be looking at the same state,
* remember to update group->polling_total[] once we've
* been through all of them. Also remember to extend the
* polling time if we see new stall activity.
*/
update_total = true;
/* Calculate growth since last update */
growth = window_update(&t->win, now, total[t->state]);
if (!t->pending_event) {
if (growth < t->threshold)
continue;
t->pending_event = true;
}
}
/* Limit event signaling to once per window */
if (now < t->last_event_time + t->win.size)
continue;
/* Generate an event */
if (cmpxchg(&t->event, 0, 1) == 0)
wake_up_interruptible(&t->event_wait);
t->last_event_time = now;
/* Reset threshold breach flag once event got generated */
t->pending_event = false;
}
if (update_total)
memcpy(group->polling_total, total,
sizeof(group->polling_total));
return now + group->poll_min_period;
memcpy(group->rtpoll_total, group->total[PSI_POLL],
sizeof(group->rtpoll_total));
group->rtpoll_next_update = now + group->rtpoll_min_period;
}
/* Schedule polling if it's not already scheduled or forced. */
static void psi_schedule_poll_work(struct psi_group *group, unsigned long delay,
static void psi_schedule_rtpoll_work(struct psi_group *group, unsigned long delay,
bool force)
{
struct task_struct *task;
/*
* atomic_xchg should be called even when !force to provide a
* full memory barrier (see the comment inside psi_poll_work).
* full memory barrier (see the comment inside psi_rtpoll_work).
*/
if (atomic_xchg(&group->poll_scheduled, 1) && !force)
if (atomic_xchg(&group->rtpoll_scheduled, 1) && !force)
return;
rcu_read_lock();
task = rcu_dereference(group->poll_task);
task = rcu_dereference(group->rtpoll_task);
/*
* kworker might be NULL in case psi_trigger_destroy races with
* psi_task_change (hotpath) which can't use locks
*/
if (likely(task))
mod_timer(&group->poll_timer, jiffies + delay);
mod_timer(&group->rtpoll_timer, jiffies + delay);
else
atomic_set(&group->poll_scheduled, 0);
atomic_set(&group->rtpoll_scheduled, 0);
rcu_read_unlock();
}
static void psi_poll_work(struct psi_group *group)
static void psi_rtpoll_work(struct psi_group *group)
{
bool force_reschedule = false;
u32 changed_states;
bool update_total;
u64 now;
mutex_lock(&group->trigger_lock);
mutex_lock(&group->rtpoll_trigger_lock);
now = sched_clock();
if (now > group->polling_until) {
if (now > group->rtpoll_until) {
/*
* We are either about to start or might stop polling if no
* state change was recorded. Resetting poll_scheduled leaves
@ -638,7 +654,7 @@ static void psi_poll_work(struct psi_group *group)
* should be negligible and polling_next_update still keeps
* updates correctly on schedule.
*/
atomic_set(&group->poll_scheduled, 0);
atomic_set(&group->rtpoll_scheduled, 0);
/*
* A task change can race with the poll worker that is supposed to
* report on it. To avoid missing events, ensure ordering between
@ -667,60 +683,64 @@ static void psi_poll_work(struct psi_group *group)
collect_percpu_times(group, PSI_POLL, &changed_states);
if (changed_states & group->poll_states) {
if (changed_states & group->rtpoll_states) {
/* Initialize trigger windows when entering polling mode */
if (now > group->polling_until)
init_triggers(group, now);
if (now > group->rtpoll_until)
init_rtpoll_triggers(group, now);
/*
* Keep the monitor active for at least the duration of the
* minimum tracking window as long as monitor states are
* changing.
*/
group->polling_until = now +
group->poll_min_period * UPDATES_PER_WINDOW;
group->rtpoll_until = now +
group->rtpoll_min_period * UPDATES_PER_WINDOW;
}
if (now > group->polling_until) {
group->polling_next_update = ULLONG_MAX;
if (now > group->rtpoll_until) {
group->rtpoll_next_update = ULLONG_MAX;
goto out;
}
if (now >= group->polling_next_update)
group->polling_next_update = update_triggers(group, now);
if (now >= group->rtpoll_next_update) {
group->rtpoll_next_update = update_triggers(group, now, &update_total, PSI_POLL);
if (update_total)
memcpy(group->rtpoll_total, group->total[PSI_POLL],
sizeof(group->rtpoll_total));
}
psi_schedule_poll_work(group,
nsecs_to_jiffies(group->polling_next_update - now) + 1,
psi_schedule_rtpoll_work(group,
nsecs_to_jiffies(group->rtpoll_next_update - now) + 1,
force_reschedule);
out:
mutex_unlock(&group->trigger_lock);
mutex_unlock(&group->rtpoll_trigger_lock);
}
static int psi_poll_worker(void *data)
static int psi_rtpoll_worker(void *data)
{
struct psi_group *group = (struct psi_group *)data;
sched_set_fifo_low(current);
while (true) {
wait_event_interruptible(group->poll_wait,
atomic_cmpxchg(&group->poll_wakeup, 1, 0) ||
wait_event_interruptible(group->rtpoll_wait,
atomic_cmpxchg(&group->rtpoll_wakeup, 1, 0) ||
kthread_should_stop());
if (kthread_should_stop())
break;
psi_poll_work(group);
psi_rtpoll_work(group);
}
return 0;
}
static void poll_timer_fn(struct timer_list *t)
{
struct psi_group *group = from_timer(group, t, poll_timer);
struct psi_group *group = from_timer(group, t, rtpoll_timer);
atomic_set(&group->poll_wakeup, 1);
wake_up_interruptible(&group->poll_wait);
atomic_set(&group->rtpoll_wakeup, 1);
wake_up_interruptible(&group->rtpoll_wait);
}
static void record_times(struct psi_group_cpu *groupc, u64 now)
@ -851,8 +871,8 @@ static void psi_group_change(struct psi_group *group, int cpu,
write_seqcount_end(&groupc->seq);
if (state_mask & group->poll_states)
psi_schedule_poll_work(group, 1, false);
if (state_mask & group->rtpoll_states)
psi_schedule_rtpoll_work(group, 1, false);
if (wake_clock && !delayed_work_pending(&group->avgs_work))
schedule_delayed_work(&group->avgs_work, PSI_FREQ);
@ -1005,8 +1025,8 @@ void psi_account_irqtime(struct task_struct *task, u32 delta)
write_seqcount_end(&groupc->seq);
if (group->poll_states & (1 << PSI_IRQ_FULL))
psi_schedule_poll_work(group, 1, false);
if (group->rtpoll_states & (1 << PSI_IRQ_FULL))
psi_schedule_rtpoll_work(group, 1, false);
} while ((group = group->parent));
}
#endif
@ -1101,7 +1121,7 @@ void psi_cgroup_free(struct cgroup *cgroup)
cancel_delayed_work_sync(&cgroup->psi->avgs_work);
free_percpu(cgroup->psi->pcpu);
/* All triggers must be removed by now */
WARN_ONCE(cgroup->psi->poll_states, "psi: trigger leak\n");
WARN_ONCE(cgroup->psi->rtpoll_states, "psi: trigger leak\n");
kfree(cgroup->psi);
}
@ -1253,16 +1273,23 @@ int psi_show(struct seq_file *m, struct psi_group *group, enum psi_res res)
}
struct psi_trigger *psi_trigger_create(struct psi_group *group,
char *buf, enum psi_res res)
char *buf, enum psi_res res, struct file *file)
{
struct psi_trigger *t;
enum psi_states state;
u32 threshold_us;
bool privileged;
u32 window_us;
if (static_branch_likely(&psi_disabled))
return ERR_PTR(-EOPNOTSUPP);
/*
* Checking the privilege here on file->f_cred implies that a privileged user
* could open the file and delegate the write to an unprivileged one.
*/
privileged = cap_raised(file->f_cred->cap_effective, CAP_SYS_RESOURCE);
if (sscanf(buf, "some %u %u", &threshold_us, &window_us) == 2)
state = PSI_IO_SOME + res * 2;
else if (sscanf(buf, "full %u %u", &threshold_us, &window_us) == 2)
@ -1282,6 +1309,13 @@ struct psi_trigger *psi_trigger_create(struct psi_group *group,
window_us > WINDOW_MAX_US)
return ERR_PTR(-EINVAL);
/*
* Unprivileged users can only use 2s windows so that averages aggregation
* work is used, and no RT threads need to be spawned.
*/
if (!privileged && window_us % 2000000)
return ERR_PTR(-EINVAL);
/* Check threshold */
if (threshold_us == 0 || threshold_us > window_us)
return ERR_PTR(-EINVAL);
@ -1301,31 +1335,40 @@ struct psi_trigger *psi_trigger_create(struct psi_group *group,
t->last_event_time = 0;
init_waitqueue_head(&t->event_wait);
t->pending_event = false;
t->aggregator = privileged ? PSI_POLL : PSI_AVGS;
mutex_lock(&group->trigger_lock);
if (privileged) {
mutex_lock(&group->rtpoll_trigger_lock);
if (!rcu_access_pointer(group->poll_task)) {
struct task_struct *task;
if (!rcu_access_pointer(group->rtpoll_task)) {
struct task_struct *task;
task = kthread_create(psi_poll_worker, group, "psimon");
if (IS_ERR(task)) {
kfree(t);
mutex_unlock(&group->trigger_lock);
return ERR_CAST(task);
task = kthread_create(psi_rtpoll_worker, group, "psimon");
if (IS_ERR(task)) {
kfree(t);
mutex_unlock(&group->rtpoll_trigger_lock);
return ERR_CAST(task);
}
atomic_set(&group->rtpoll_wakeup, 0);
wake_up_process(task);
rcu_assign_pointer(group->rtpoll_task, task);
}
atomic_set(&group->poll_wakeup, 0);
wake_up_process(task);
rcu_assign_pointer(group->poll_task, task);
list_add(&t->node, &group->rtpoll_triggers);
group->rtpoll_min_period = min(group->rtpoll_min_period,
div_u64(t->win.size, UPDATES_PER_WINDOW));
group->rtpoll_nr_triggers[t->state]++;
group->rtpoll_states |= (1 << t->state);
mutex_unlock(&group->rtpoll_trigger_lock);
} else {
mutex_lock(&group->avgs_lock);
list_add(&t->node, &group->avg_triggers);
group->avg_nr_triggers[t->state]++;
mutex_unlock(&group->avgs_lock);
}
list_add(&t->node, &group->triggers);
group->poll_min_period = min(group->poll_min_period,
div_u64(t->win.size, UPDATES_PER_WINDOW));
group->nr_triggers[t->state]++;
group->poll_states |= (1 << t->state);
mutex_unlock(&group->trigger_lock);
return t;
}
@ -1349,51 +1392,59 @@ void psi_trigger_destroy(struct psi_trigger *t)
*/
wake_up_pollfree(&t->event_wait);
mutex_lock(&group->trigger_lock);
if (!list_empty(&t->node)) {
struct psi_trigger *tmp;
u64 period = ULLONG_MAX;
list_del(&t->node);
group->nr_triggers[t->state]--;
if (!group->nr_triggers[t->state])
group->poll_states &= ~(1 << t->state);
/* reset min update period for the remaining triggers */
list_for_each_entry(tmp, &group->triggers, node)
period = min(period, div_u64(tmp->win.size,
UPDATES_PER_WINDOW));
group->poll_min_period = period;
/* Destroy poll_task when the last trigger is destroyed */
if (group->poll_states == 0) {
group->polling_until = 0;
task_to_destroy = rcu_dereference_protected(
group->poll_task,
lockdep_is_held(&group->trigger_lock));
rcu_assign_pointer(group->poll_task, NULL);
del_timer(&group->poll_timer);
if (t->aggregator == PSI_AVGS) {
mutex_lock(&group->avgs_lock);
if (!list_empty(&t->node)) {
list_del(&t->node);
group->avg_nr_triggers[t->state]--;
}
mutex_unlock(&group->avgs_lock);
} else {
mutex_lock(&group->rtpoll_trigger_lock);
if (!list_empty(&t->node)) {
struct psi_trigger *tmp;
u64 period = ULLONG_MAX;
list_del(&t->node);
group->rtpoll_nr_triggers[t->state]--;
if (!group->rtpoll_nr_triggers[t->state])
group->rtpoll_states &= ~(1 << t->state);
/* reset min update period for the remaining triggers */
list_for_each_entry(tmp, &group->rtpoll_triggers, node)
period = min(period, div_u64(tmp->win.size,
UPDATES_PER_WINDOW));
group->rtpoll_min_period = period;
/* Destroy rtpoll_task when the last trigger is destroyed */
if (group->rtpoll_states == 0) {
group->rtpoll_until = 0;
task_to_destroy = rcu_dereference_protected(
group->rtpoll_task,
lockdep_is_held(&group->rtpoll_trigger_lock));
rcu_assign_pointer(group->rtpoll_task, NULL);
del_timer(&group->rtpoll_timer);
}
}
mutex_unlock(&group->rtpoll_trigger_lock);
}
mutex_unlock(&group->trigger_lock);
/*
* Wait for psi_schedule_poll_work RCU to complete its read-side
* Wait for psi_schedule_rtpoll_work RCU to complete its read-side
* critical section before destroying the trigger and optionally the
* poll_task.
* rtpoll_task.
*/
synchronize_rcu();
/*
* Stop kthread 'psimon' after releasing trigger_lock to prevent a
* deadlock while waiting for psi_poll_work to acquire trigger_lock
* Stop kthread 'psimon' after releasing rtpoll_trigger_lock to prevent
* a deadlock while waiting for psi_rtpoll_work to acquire
* rtpoll_trigger_lock
*/
if (task_to_destroy) {
/*
* After the RCU grace period has expired, the worker
* can no longer be found through group->poll_task.
* can no longer be found through group->rtpoll_task.
*/
kthread_stop(task_to_destroy);
atomic_set(&group->poll_scheduled, 0);
atomic_set(&group->rtpoll_scheduled, 0);
}
kfree(t);
}
@ -1435,27 +1486,19 @@ static int psi_cpu_show(struct seq_file *m, void *v)
return psi_show(m, &psi_system, PSI_CPU);
}
static int psi_open(struct file *file, int (*psi_show)(struct seq_file *, void *))
{
if (file->f_mode & FMODE_WRITE && !capable(CAP_SYS_RESOURCE))
return -EPERM;
return single_open(file, psi_show, NULL);
}
static int psi_io_open(struct inode *inode, struct file *file)
{
return psi_open(file, psi_io_show);
return single_open(file, psi_io_show, NULL);
}
static int psi_memory_open(struct inode *inode, struct file *file)
{
return psi_open(file, psi_memory_show);
return single_open(file, psi_memory_show, NULL);
}
static int psi_cpu_open(struct inode *inode, struct file *file)
{
return psi_open(file, psi_cpu_show);
return single_open(file, psi_cpu_show, NULL);
}
static ssize_t psi_write(struct file *file, const char __user *user_buf,
@ -1489,7 +1532,7 @@ static ssize_t psi_write(struct file *file, const char __user *user_buf,
return -EBUSY;
}
new = psi_trigger_create(&psi_system, buf, res);
new = psi_trigger_create(&psi_system, buf, res, file);
if (IS_ERR(new)) {
mutex_unlock(&seq->lock);
return PTR_ERR(new);
@ -1569,7 +1612,7 @@ static int psi_irq_show(struct seq_file *m, void *v)
static int psi_irq_open(struct inode *inode, struct file *file)
{
return psi_open(file, psi_irq_show);
return single_open(file, psi_irq_show, NULL);
}
static ssize_t psi_irq_write(struct file *file, const char __user *user_buf,

23
kernel/sched/rt.c
View File

@ -2000,11 +2000,15 @@ static struct rq *find_lock_lowest_rq(struct task_struct *task, struct rq *rq)
* the mean time, task could have
* migrated already or had its affinity changed.
* Also make sure that it wasn't scheduled on its rq.
* It is possible the task was scheduled, set
* "migrate_disabled" and then got preempted, so we must
* check the task migration disable flag here too.
*/
if (unlikely(task_rq(task) != rq ||
!cpumask_test_cpu(lowest_rq->cpu, &task->cpus_mask) ||
task_on_cpu(rq, task) ||
!rt_task(task) ||
is_migration_disabled(task) ||
!task_on_rq_queued(task))) {
double_unlock_balance(rq, lowest_rq);
@ -2677,6 +2681,21 @@ static unsigned int get_rr_interval_rt(struct rq *rq, struct task_struct *task)
return 0;
}
#ifdef CONFIG_SCHED_CORE
static int task_is_throttled_rt(struct task_struct *p, int cpu)
{
struct rt_rq *rt_rq;
#ifdef CONFIG_RT_GROUP_SCHED
rt_rq = task_group(p)->rt_rq[cpu];
#else
rt_rq = &cpu_rq(cpu)->rt;
#endif
return rt_rq_throttled(rt_rq);
}
#endif
DEFINE_SCHED_CLASS(rt) = {
.enqueue_task = enqueue_task_rt,
@ -2710,6 +2729,10 @@ DEFINE_SCHED_CLASS(rt) = {
.update_curr = update_curr_rt,
#ifdef CONFIG_SCHED_CORE
.task_is_throttled = task_is_throttled_rt,
#endif
#ifdef CONFIG_UCLAMP_TASK
.uclamp_enabled = 1,
#endif

243
kernel/sched/sched.h
View File

@ -2224,6 +2224,10 @@ struct sched_class {
#ifdef CONFIG_FAIR_GROUP_SCHED
void (*task_change_group)(struct task_struct *p);
#endif
#ifdef CONFIG_SCHED_CORE
int (*task_is_throttled)(struct task_struct *p, int cpu);
#endif
};
static inline void put_prev_task(struct rq *rq, struct task_struct *prev)
@ -3249,61 +3253,238 @@ static inline void update_current_exec_runtime(struct task_struct *curr,
}
#ifdef CONFIG_SCHED_MM_CID
static inline int __mm_cid_get(struct mm_struct *mm)
#define SCHED_MM_CID_PERIOD_NS (100ULL * 1000000) /* 100ms */
#define MM_CID_SCAN_DELAY 100 /* 100ms */
extern raw_spinlock_t cid_lock;
extern int use_cid_lock;
extern void sched_mm_cid_migrate_from(struct task_struct *t);
extern void sched_mm_cid_migrate_to(struct rq *dst_rq, struct task_struct *t);
extern void task_tick_mm_cid(struct rq *rq, struct task_struct *curr);
extern void init_sched_mm_cid(struct task_struct *t);
static inline void __mm_cid_put(struct mm_struct *mm, int cid)
{
if (cid < 0)
return;
cpumask_clear_cpu(cid, mm_cidmask(mm));
}
/*
* The per-mm/cpu cid can have the MM_CID_LAZY_PUT flag set or transition to
* the MM_CID_UNSET state without holding the rq lock, but the rq lock needs to
* be held to transition to other states.
*
* State transitions synchronized with cmpxchg or try_cmpxchg need to be
* consistent across cpus, which prevents use of this_cpu_cmpxchg.
*/
static inline void mm_cid_put_lazy(struct task_struct *t)
{
struct mm_struct *mm = t->mm;
struct mm_cid __percpu *pcpu_cid = mm->pcpu_cid;
int cid;
lockdep_assert_irqs_disabled();
cid = __this_cpu_read(pcpu_cid->cid);
if (!mm_cid_is_lazy_put(cid) ||
!try_cmpxchg(&this_cpu_ptr(pcpu_cid)->cid, &cid, MM_CID_UNSET))
return;
__mm_cid_put(mm, mm_cid_clear_lazy_put(cid));
}
static inline int mm_cid_pcpu_unset(struct mm_struct *mm)
{
struct mm_cid __percpu *pcpu_cid = mm->pcpu_cid;
int cid, res;
lockdep_assert_irqs_disabled();
cid = __this_cpu_read(pcpu_cid->cid);
for (;;) {
if (mm_cid_is_unset(cid))
return MM_CID_UNSET;
/*
* Attempt transition from valid or lazy-put to unset.
*/
res = cmpxchg(&this_cpu_ptr(pcpu_cid)->cid, cid, MM_CID_UNSET);
if (res == cid)
break;
cid = res;
}
return cid;
}
static inline void mm_cid_put(struct mm_struct *mm)
{
int cid;
lockdep_assert_irqs_disabled();
cid = mm_cid_pcpu_unset(mm);
if (cid == MM_CID_UNSET)
return;
__mm_cid_put(mm, mm_cid_clear_lazy_put(cid));
}
static inline int __mm_cid_try_get(struct mm_struct *mm)
{
struct cpumask *cpumask;
int cid;
cpumask = mm_cidmask(mm);
cid = cpumask_first_zero(cpumask);
if (cid >= nr_cpu_ids)
/*
* Retry finding first zero bit if the mask is temporarily
* filled. This only happens during concurrent remote-clear
* which owns a cid without holding a rq lock.
*/
for (;;) {
cid = cpumask_first_zero(cpumask);
if (cid < nr_cpu_ids)
break;
cpu_relax();
}
if (cpumask_test_and_set_cpu(cid, cpumask))
return -1;
__cpumask_set_cpu(cid, cpumask);
return cid;
}
static inline void mm_cid_put(struct mm_struct *mm, int cid)
/*
* Save a snapshot of the current runqueue time of this cpu
* with the per-cpu cid value, allowing to estimate how recently it was used.
*/
static inline void mm_cid_snapshot_time(struct rq *rq, struct mm_struct *mm)
{
lockdep_assert_irqs_disabled();
if (cid < 0)
return;
raw_spin_lock(&mm->cid_lock);
__cpumask_clear_cpu(cid, mm_cidmask(mm));
raw_spin_unlock(&mm->cid_lock);
struct mm_cid *pcpu_cid = per_cpu_ptr(mm->pcpu_cid, cpu_of(rq));
lockdep_assert_rq_held(rq);
WRITE_ONCE(pcpu_cid->time, rq->clock);
}
static inline int mm_cid_get(struct mm_struct *mm)
static inline int __mm_cid_get(struct rq *rq, struct mm_struct *mm)
{
int ret;
int cid;
lockdep_assert_irqs_disabled();
raw_spin_lock(&mm->cid_lock);
ret = __mm_cid_get(mm);
raw_spin_unlock(&mm->cid_lock);
return ret;
/*
* All allocations (even those using the cid_lock) are lock-free. If
* use_cid_lock is set, hold the cid_lock to perform cid allocation to
* guarantee forward progress.
*/
if (!READ_ONCE(use_cid_lock)) {
cid = __mm_cid_try_get(mm);
if (cid >= 0)
goto end;
raw_spin_lock(&cid_lock);
} else {
raw_spin_lock(&cid_lock);
cid = __mm_cid_try_get(mm);
if (cid >= 0)
goto unlock;
}
/*
* cid concurrently allocated. Retry while forcing following
* allocations to use the cid_lock to ensure forward progress.
*/
WRITE_ONCE(use_cid_lock, 1);
/*
* Set use_cid_lock before allocation. Only care about program order
* because this is only required for forward progress.
*/
barrier();
/*
* Retry until it succeeds. It is guaranteed to eventually succeed once
* all newcoming allocations observe the use_cid_lock flag set.
*/
do {
cid = __mm_cid_try_get(mm);
cpu_relax();
} while (cid < 0);
/*
* Allocate before clearing use_cid_lock. Only care about
* program order because this is for forward progress.
*/
barrier();
WRITE_ONCE(use_cid_lock, 0);
unlock:
raw_spin_unlock(&cid_lock);
end:
mm_cid_snapshot_time(rq, mm);
return cid;
}
static inline void switch_mm_cid(struct task_struct *prev, struct task_struct *next)
static inline int mm_cid_get(struct rq *rq, struct mm_struct *mm)
{
struct mm_cid __percpu *pcpu_cid = mm->pcpu_cid;
struct cpumask *cpumask;
int cid;
lockdep_assert_rq_held(rq);
cpumask = mm_cidmask(mm);
cid = __this_cpu_read(pcpu_cid->cid);
if (mm_cid_is_valid(cid)) {
mm_cid_snapshot_time(rq, mm);
return cid;
}
if (mm_cid_is_lazy_put(cid)) {
if (try_cmpxchg(&this_cpu_ptr(pcpu_cid)->cid, &cid, MM_CID_UNSET))
__mm_cid_put(mm, mm_cid_clear_lazy_put(cid));
}
cid = __mm_cid_get(rq, mm);
__this_cpu_write(pcpu_cid->cid, cid);
return cid;
}
static inline void switch_mm_cid(struct rq *rq,
struct task_struct *prev,
struct task_struct *next)
{
/*
* Provide a memory barrier between rq->curr store and load of
* {prev,next}->mm->pcpu_cid[cpu] on rq->curr->mm transition.
*
* Should be adapted if context_switch() is modified.
*/
if (!next->mm) { // to kernel
/*
* user -> kernel transition does not guarantee a barrier, but
* we can use the fact that it performs an atomic operation in
* mmgrab().
*/
if (prev->mm) // from user
smp_mb__after_mmgrab();
/*
* kernel -> kernel transition does not change rq->curr->mm
* state. It stays NULL.
*/
} else { // to user
/*
* kernel -> user transition does not provide a barrier
* between rq->curr store and load of {prev,next}->mm->pcpu_cid[cpu].
* Provide it here.
*/
if (!prev->mm) // from kernel
smp_mb();
/*
* user -> user transition guarantees a memory barrier through
* switch_mm() when current->mm changes. If current->mm is
* unchanged, no barrier is needed.
*/
}
if (prev->mm_cid_active) {
if (next->mm_cid_active && next->mm == prev->mm) {
/*
* Context switch between threads in same mm, hand over
* the mm_cid from prev to next.
*/
next->mm_cid = prev->mm_cid;
prev->mm_cid = -1;
return;
}
mm_cid_put(prev->mm, prev->mm_cid);
mm_cid_snapshot_time(rq, prev->mm);
mm_cid_put_lazy(prev);
prev->mm_cid = -1;
}
if (next->mm_cid_active)
next->mm_cid = mm_cid_get(next->mm);
next->last_mm_cid = next->mm_cid = mm_cid_get(rq, next->mm);
}
#else
static inline void switch_mm_cid(struct task_struct *prev, struct task_struct *next) { }
static inline void switch_mm_cid(struct rq *rq, struct task_struct *prev, struct task_struct *next) { }
static inline void sched_mm_cid_migrate_from(struct task_struct *t) { }
static inline void sched_mm_cid_migrate_to(struct rq *dst_rq, struct task_struct *t) { }
static inline void task_tick_mm_cid(struct rq *rq, struct task_struct *curr) { }
static inline void init_sched_mm_cid(struct task_struct *t) { }
#endif
#endif /* _KERNEL_SCHED_SCHED_H */

4
kernel/sched/topology.c
View File

@ -209,8 +209,8 @@ sd_parent_degenerate(struct sched_domain *sd, struct sched_domain *parent)
#if defined(CONFIG_ENERGY_MODEL) && defined(CONFIG_CPU_FREQ_GOV_SCHEDUTIL)
DEFINE_STATIC_KEY_FALSE(sched_energy_present);
static unsigned int sysctl_sched_energy_aware = 1;
DEFINE_MUTEX(sched_energy_mutex);
bool sched_energy_update;
static DEFINE_MUTEX(sched_energy_mutex);
static bool sched_energy_update;
void rebuild_sched_domains_energy(void)
{