Pull smp hotplug cleanups from Thomas Gleixner:
"This series is merily a cleanup of code copied around in arch/* and
not changing any of the real cpu hotplug horrors yet. I wish I'd had
something more substantial for 3.5, but I underestimated the lurking
horror..."
Fix up trivial conflicts in arch/{arm,sparc,x86}/Kconfig and
arch/sparc/include/asm/thread_info_32.h
* 'smp-hotplug-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (79 commits)
um: Remove leftover declaration of alloc_task_struct_node()
task_allocator: Use config switches instead of magic defines
sparc: Use common threadinfo allocator
score: Use common threadinfo allocator
sh-use-common-threadinfo-allocator
mn10300: Use common threadinfo allocator
powerpc: Use common threadinfo allocator
mips: Use common threadinfo allocator
hexagon: Use common threadinfo allocator
m32r: Use common threadinfo allocator
frv: Use common threadinfo allocator
cris: Use common threadinfo allocator
x86: Use common threadinfo allocator
c6x: Use common threadinfo allocator
fork: Provide kmemcache based thread_info allocator
tile: Use common threadinfo allocator
fork: Provide weak arch_release_[task_struct|thread_info] functions
fork: Move thread info gfp flags to header
fork: Remove the weak insanity
sh: Remove cpu_idle_wait()
...
Pull RCU changes from Ingo Molnar:
"This is the v3.5 RCU tree from Paul E. McKenney:
1) A set of improvements and fixes to the RCU_FAST_NO_HZ feature (with
more on the way for 3.6). Posted to LKML:
https://lkml.org/lkml/2012/4/23/324 (commits 1-3 and 5),
https://lkml.org/lkml/2012/4/16/611 (commit 4),
https://lkml.org/lkml/2012/4/30/390 (commit 6), and
https://lkml.org/lkml/2012/5/4/410 (commit 7, combined with
the other commits for the convenience of the tester).
2) Changes to make rcu_barrier() avoid disrupting execution of CPUs
that have no RCU callbacks. Posted to LKML:
https://lkml.org/lkml/2012/4/23/322.
3) A couple of commits that improve the efficiency of the interaction
between preemptible RCU and the scheduler, these two being all that
survived an abortive attempt to allow preemptible RCU's
__rcu_read_lock() to be inlined. The full set was posted to LKML at
https://lkml.org/lkml/2012/4/14/143, and the first and third patches
of that set remain.
4) Lai Jiangshan's algorithmic implementation of SRCU, which includes
call_srcu() and srcu_barrier(). A major feature of this new
implementation is that synchronize_srcu() no longer disturbs the
execution of other CPUs. This work is based on earlier
implementations by Peter Zijlstra and Paul E. McKenney. Posted to
LKML: https://lkml.org/lkml/2012/2/22/82.
5) A number of miscellaneous bug fixes and improvements which were
posted to LKML at: https://lkml.org/lkml/2012/4/23/353 with
subsequent updates posted to LKML."
* 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (32 commits)
rcu: Make rcu_barrier() less disruptive
rcu: Explicitly initialize RCU_FAST_NO_HZ per-CPU variables
rcu: Make RCU_FAST_NO_HZ handle timer migration
rcu: Update RCU maintainership
rcu: Make exit_rcu() more precise and consolidate
rcu: Move PREEMPT_RCU preemption to switch_to() invocation
rcu: Ensure that RCU_FAST_NO_HZ timers expire on correct CPU
rcu: Add rcutorture test for call_srcu()
rcu: Implement per-domain single-threaded call_srcu() state machine
rcu: Use single value to handle expedited SRCU grace periods
rcu: Improve srcu_readers_active_idx()'s cache locality
rcu: Remove unused srcu_barrier()
rcu: Implement a variant of Peter's SRCU algorithm
rcu: Improve SRCU's wait_idx() comments
rcu: Flip ->completed only once per SRCU grace period
rcu: Increment upper bit only for srcu_read_lock()
rcu: Remove fast check path from __synchronize_srcu()
rcu: Direct algorithmic SRCU implementation
rcu: Introduce rcutorture testing for rcu_barrier()
timer: Fix mod_timer_pinned() header comment
...
Pull the v3.5 RCU tree from Paul E. McKenney:
1) A set of improvements and fixes to the RCU_FAST_NO_HZ feature
(with more on the way for 3.6). Posted to LKML:
https://lkml.org/lkml/2012/4/23/324 (commits 1-3 and 5),
https://lkml.org/lkml/2012/4/16/611 (commit 4),
https://lkml.org/lkml/2012/4/30/390 (commit 6), and
https://lkml.org/lkml/2012/5/4/410 (commit 7, combined with
the other commits for the convenience of the tester).
2) Changes to make rcu_barrier() avoid disrupting execution of CPUs
that have no RCU callbacks. Posted to LKML:
https://lkml.org/lkml/2012/4/23/322.
3) A couple of commits that improve the efficiency of the interaction
between preemptible RCU and the scheduler, these two being all
that survived an abortive attempt to allow preemptible RCU's
__rcu_read_lock() to be inlined. The full set was posted to
LKML at https://lkml.org/lkml/2012/4/14/143, and the first and
third patches of that set remain.
4) Lai Jiangshan's algorithmic implementation of SRCU, which includes
call_srcu() and srcu_barrier(). A major feature of this new
implementation is that synchronize_srcu() no longer disturbs
the execution of other CPUs. This work is based on earlier
implementations by Peter Zijlstra and Paul E. McKenney. Posted to
LKML: https://lkml.org/lkml/2012/2/22/82.
5) A number of miscellaneous bug fixes and improvements which were
posted to LKML at: https://lkml.org/lkml/2012/4/23/353 with
subsequent updates posted to LKML.
Signed-off-by: Ingo Molnar <mingo@kernel.org>
If we have one cpu that failed to boot and boot cpu gave up on
waiting for it and then another cpu is being booted, kernel
might crash with following OOPS:
BUG: unable to handle kernel NULL pointer dereference at 0000000000000018
IP: [<ffffffff812c3630>] __bitmap_weight+0x30/0x80
Call Trace:
[<ffffffff8108b9b6>] build_sched_domains+0x7b6/0xa50
The crash happens in init_sched_groups_power() that expects
sched_groups to be circular linked list. However it is not
always true, since sched_groups preallocated in __sdt_alloc are
initialized in build_sched_groups and it may exit early
if (cpu != cpumask_first(sched_domain_span(sd)))
return 0;
without initializing sd->groups->next field.
Fix bug by initializing next field right after sched_group was
allocated.
Also-Reported-by: Jiang Liu <liuj97@gmail.com>
Signed-off-by: Igor Mammedov <imammedo@redhat.com>
Cc: a.p.zijlstra@chello.nl
Cc: pjt@google.com
Cc: seto.hidetoshi@jp.fujitsu.com
Link: http://lkml.kernel.org/r/1336559908-32533-1-git-send-email-imammedo@redhat.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
All archs define init_task in the same way (except ia64, but there is
no particular reason why ia64 cannot use the common version). Create a
generic instance so all archs can be converted over.
The config switch is temporary and will be removed when all archs are
converted over.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Chen Liqin <liqin.chen@sunplusct.com>
Cc: Chris Metcalf <cmetcalf@tilera.com>
Cc: Chris Zankel <chris@zankel.net>
Cc: David Howells <dhowells@redhat.com>
Cc: David S. Miller <davem@davemloft.net>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Guan Xuetao <gxt@mprc.pku.edu.cn>
Cc: Haavard Skinnemoen <hskinnemoen@gmail.com>
Cc: Hirokazu Takata <takata@linux-m32r.org>
Cc: James E.J. Bottomley <jejb@parisc-linux.org>
Cc: Jesper Nilsson <jesper.nilsson@axis.com>
Cc: Jonas Bonn <jonas@southpole.se>
Cc: Mark Salter <msalter@redhat.com>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Heiko Carstens <heiko.carstens@de.ibm.com>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Michal Simek <monstr@monstr.eu>
Cc: Mike Frysinger <vapier@gentoo.org>
Cc: Paul Mundt <lethal@linux-sh.org>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: Richard Kuo <rkuo@codeaurora.org>
Cc: Richard Weinberger <richard@nod.at>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Yoshinori Sato <ysato@users.sourceforge.jp>
Link: http://lkml.kernel.org/r/20120503085034.092585287@linutronix.de
Currently, PREEMPT_RCU readers are enqueued upon entry to the scheduler.
This is inefficient because enqueuing is required only if there is a
context switch, and entry to the scheduler does not guarantee a context
switch.
The commit therefore moves the enqueuing to immediately precede the
call to switch_to() from the scheduler.
Signed-off-by: Paul E. McKenney <paul.mckenney@linaro.org>
Signed-off-by: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Tested-by: Linus Torvalds <torvalds@linux-foundation.org>
Under extreme memory used up situations, percpu allocation
might fail. We hit it when system goes to suspend-to-ram,
causing a kworker panic:
EIP: [<c124411a>] build_sched_domains+0x23a/0xad0
Kernel panic - not syncing: Fatal exception
Pid: 3026, comm: kworker/u:3
3.0.8-137473-gf42fbef #1
Call Trace:
[<c18cc4f2>] panic+0x66/0x16c
[...]
[<c1244c37>] partition_sched_domains+0x287/0x4b0
[<c12a77be>] cpuset_update_active_cpus+0x1fe/0x210
[<c123712d>] cpuset_cpu_inactive+0x1d/0x30
[...]
With this fix applied build_sched_domains() will return -ENOMEM and
the suspend attempt fails.
Signed-off-by: he, bo <bo.he@intel.com>
Reviewed-by: Zhang, Yanmin <yanmin.zhang@intel.com>
Reviewed-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: <stable@kernel.org>
Link: http://lkml.kernel.org/r/1335355161.5892.17.camel@hebo
[ So, we fail to deallocate a CPU because we cannot allocate RAM :-/
I don't like that kind of sad behavior but nevertheless it should
not crash under high memory load. ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Commits 367456c756 ("sched: Ditch per cgroup task lists for
load-balancing") and 5d6523ebd ("sched: Fix load-balance wreckage")
left some more wreckage.
By setting loop_max unconditionally to ->nr_running load-balancing
could take a lot of time on very long runqueues (hackbench!). So keep
the sysctl as max limit of the amount of tasks we'll iterate.
Furthermore, the min load filter for migration completely fails with
cgroups since inequality in per-cpu state can easily lead to such
small loads :/
Furthermore the change to add new tasks to the tail of the queue
instead of the head seems to have some effect.. not quite sure I
understand why.
Combined these fixes solve the huge hackbench regression reported by
Tim when hackbench is ran in a cgroup.
Reported-by: Tim Chen <tim.c.chen@linux.intel.com>
Acked-by: Tim Chen <tim.c.chen@linux.intel.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Link: http://lkml.kernel.org/r/1335365763.28150.267.camel@twins
[ got rid of the CONFIG_PREEMPT tuning and made small readability edits ]
Signed-off-by: Ingo Molnar <mingo@kernel.org>
All SMP architectures have magic to fork the idle task and to store it
for reusage when cpu hotplug is enabled. Provide a generic
infrastructure for it.
Create/reinit the idle thread for the cpu which is brought up in the
generic code and hand the thread pointer to the architecture code via
__cpu_up().
Note, that fork_idle() is called via a workqueue, because this
guarantees that the idle thread does not get a reference to a user
space VM. This can happen when the boot process did not bring up all
possible cpus and a later cpu_up() is initiated via the sysfs
interface. In that case fork_idle() would be called in the context of
the user space task and take a reference on the user space VM.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Rusty Russell <rusty@rustcorp.com.au>
Cc: Paul E. McKenney <paulmck@linux.vnet.ibm.com>
Cc: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Cc: Matt Turner <mattst88@gmail.com>
Cc: Russell King <linux@arm.linux.org.uk>
Cc: Mike Frysinger <vapier@gentoo.org>
Cc: Jesper Nilsson <jesper.nilsson@axis.com>
Cc: Richard Kuo <rkuo@codeaurora.org>
Cc: Tony Luck <tony.luck@intel.com>
Cc: Hirokazu Takata <takata@linux-m32r.org>
Cc: Ralf Baechle <ralf@linux-mips.org>
Cc: David Howells <dhowells@redhat.com>
Cc: James E.J. Bottomley <jejb@parisc-linux.org>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Paul Mundt <lethal@linux-sh.org>
Cc: David S. Miller <davem@davemloft.net>
Cc: Chris Metcalf <cmetcalf@tilera.com>
Cc: Richard Weinberger <richard@nod.at>
Cc: x86@kernel.org
Acked-by: Venkatesh Pallipadi <venki@google.com>
Link: http://lkml.kernel.org/r/20120420124557.102478630@linutronix.de
Pull scheduler fixes from Ingo Molnar.
* 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
sched: Fix incorrect usage of for_each_cpu_mask() in select_fallback_rq()
sched: Fix __schedule_bug() output when called from an interrupt
sched/arch: Introduce the finish_arch_post_lock_switch() scheduler callback
The function for_each_cpu_mask() expects a *pointer* to struct
cpumask as its second argument, whereas select_fallback_rq()
passes the value itself.
And moreover, for_each_cpu_mask() has been marked as obselete
in include/linux/cpumask.h. So move to the more appropriate
for_each_cpu() variant.
Reported-by: Sasha Levin <levinsasha928@gmail.com>
Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Dave Jones <davej@redhat.com>
Cc: Liu Chuansheng <chuansheng.liu@intel.com>
Cc: vapier@gentoo.org
Cc: rusty@rustcorp.com.au
Link: http://lkml.kernel.org/r/4F75BED4.9050005@linux.vnet.ibm.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Pull scheduler fixes from Ingo Molnar.
* 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip:
cpusets: Remove an unused variable
sched/rt: Improve pick_next_highest_task_rt()
sched: Fix select_fallback_rq() vs cpu_active/cpu_online
sched/x86/smp: Do not enable IRQs over calibrate_delay()
sched: Fix compiler warning about declared inline after use
MAINTAINERS: Update email address for SCHEDULER and PERF EVENTS
If schedule is called from an interrupt handler __schedule_bug()
will call show_regs() with the registers saved during the
interrupt handling done in do_IRQ(). This means we'll see the
registers and the backtrace for the process that was interrupted
and not the full backtrace explaining who called schedule().
This is due to 838225b ("sched: use show_regs() to improve
__schedule_bug() output", 2007-10-24) which improperly assumed
that get_irq_regs() would return the registers for the current
stack because it is being called from within an interrupt
handler. Simply remove the show_reg() code so that we dump a
backtrace for the interrupt handler that called schedule().
[ I ran across this when I was presented with a scheduling while
atomic log with a stacktrace pointing at spin_unlock_irqrestore().
It made no sense and I had to guess what interrupt handler could
be called and poke around for someone calling schedule() in an
interrupt handler. A simple test of putting an msleep() in
an interrupt handler works better with this patch because you
can actually see the msleep() call in the backtrace. ]
Also-reported-by: Chris Metcalf <cmetcalf@tilera.com>
Signed-off-by: Stephen Boyd <sboyd@codeaurora.org>
Cc: Satyam Sharma <satyam@infradead.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/1332979847-27102-1-git-send-email-sboyd@codeaurora.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
asm/system.h is a cause of circular dependency problems because it contains
commonly used primitive stuff like barrier definitions and uncommonly used
stuff like switch_to() that might require MMU definitions.
asm/system.h has been disintegrated by this point on all arches into the
following common segments:
(1) asm/barrier.h
Moved memory barrier definitions here.
(2) asm/cmpxchg.h
Moved xchg() and cmpxchg() here. #included in asm/atomic.h.
(3) asm/bug.h
Moved die() and similar here.
(4) asm/exec.h
Moved arch_align_stack() here.
(5) asm/elf.h
Moved AT_VECTOR_SIZE_ARCH here.
(6) asm/switch_to.h
Moved switch_to() here.
Signed-off-by: David Howells <dhowells@redhat.com>
Avoid extra work by continuing on to the next rt_rq if the highest
prio task in current rt_rq is the same priority as our candidate
task.
More detailed explanation: if next is not NULL, then we have found a
candidate task, and its priority is next->prio. Now we are looking
for an even higher priority task in the other rt_rq's. idx is the
highest priority in the current candidate rt_rq. In the current 3.3
code, if idx is equal to next->prio, we would start scanning the tasks
in that rt_rq and replace the current candidate task with a task from
that rt_rq. But the new task would only have a priority that is equal
to our previous candidate task, so we have not advanced our goal of
finding a higher prio task. So we should avoid the extra work by
continuing on to the next rt_rq if idx is equal to next->prio.
Signed-off-by: Michael J Wang <mjwang@broadcom.com>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Reviewed-by: Yong Zhang <yong.zhang0@gmail.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/2EF88150C0EF2C43A218742ED384C1BC0FC83D6B@IRVEXCHMB08.corp.ad.broadcom.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Commit 5fbd036b55 ("sched: Cleanup cpu_active madness"), which was
supposed to finally sort the cpu_active mess, instead uncovered more.
Since CPU_STARTING is ran before setting the cpu online, there's a
(small) window where the cpu has active,!online.
If during this time there's a wakeup of a task that used to reside on
that cpu select_task_rq() will use select_fallback_rq() to compute an
alternative cpu to run on since we find !online.
select_fallback_rq() however will compute the new cpu against
cpu_active, this means that it can return the same cpu it started out
with, the !online one, since that cpu is in fact marked active.
This results in us trying to scheduling a task on an offline cpu and
triggering a WARN in the IPI code.
The solution proposed by Chuansheng Liu of setting cpu_active in
set_cpu_online() is buggy, firstly not all archs actually use
set_cpu_online(), secondly, not all archs call set_cpu_online() with
IRQs disabled, this means we would introduce either the same race or
the race from fd8a7de17 ("x86: cpu-hotplug: Prevent softirq wakeup on
wrong CPU") -- albeit much narrower.
[ By setting online first and active later we have a window of
online,!active, fresh and bound kthreads have task_cpu() of 0 and
since cpu0 isn't in tsk_cpus_allowed() we end up in
select_fallback_rq() which excludes !active, resulting in a reset
of ->cpus_allowed and the thread running all over the place. ]
The solution is to re-work select_fallback_rq() to require active
_and_ online. This makes the active,!online case work as expected,
OTOH archs running CPU_STARTING after setting online are now
vulnerable to the issue from fd8a7de17 -- these are alpha and
blackfin.
Reported-by: Chuansheng Liu <chuansheng.liu@intel.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Mike Frysinger <vapier@gentoo.org>
Cc: linux-alpha@vger.kernel.org
Link: http://lkml.kernel.org/n/tip-hubqk1i10o4dpvlm06gq7v6j@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@kernel.org>
kernel/sched/fair.c:420: warning: 'account_cfs_rq_runtime' declared inline after being called
kernel/sched/fair.c:420: warning: previous declaration of 'account_cfs_rq_runtime' was here
kernel/sched/fair.c:1165: warning: 'return_cfs_rq_runtime' declared inlineafter being called
kernel/sched/fair.c:1165: warning: previous declaration of 'return_cfs_rq_runtime' was here
Reported-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Link: http://lkml.kernel.org/r/20120321200717.49BB4A024E@akpm.mtv.corp.google.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Pull security subsystem updates for 3.4 from James Morris:
"The main addition here is the new Yama security module from Kees Cook,
which was discussed at the Linux Security Summit last year. Its
purpose is to collect miscellaneous DAC security enhancements in one
place. This also marks a departure in policy for LSM modules, which
were previously limited to being standalone access control systems.
Chromium OS is using Yama, and I believe there are plans for Ubuntu,
at least.
This patchset also includes maintenance updates for AppArmor, TOMOYO
and others."
Fix trivial conflict in <net/sock.h> due to the jumo_label->static_key
rename.
* 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/jmorris/linux-security: (38 commits)
AppArmor: Fix location of const qualifier on generated string tables
TOMOYO: Return error if fails to delete a domain
AppArmor: add const qualifiers to string arrays
AppArmor: Add ability to load extended policy
TOMOYO: Return appropriate value to poll().
AppArmor: Move path failure information into aa_get_name and rename
AppArmor: Update dfa matching routines.
AppArmor: Minor cleanup of d_namespace_path to consolidate error handling
AppArmor: Retrieve the dentry_path for error reporting when path lookup fails
AppArmor: Add const qualifiers to generated string tables
AppArmor: Fix oops in policy unpack auditing
AppArmor: Fix error returned when a path lookup is disconnected
KEYS: testing wrong bit for KEY_FLAG_REVOKED
TOMOYO: Fix mount flags checking order.
security: fix ima kconfig warning
AppArmor: Fix the error case for chroot relative path name lookup
AppArmor: fix mapping of META_READ to audit and quiet flags
AppArmor: Fix underflow in xindex calculation
AppArmor: Fix dropping of allowed operations that are force audited
AppArmor: Add mising end of structure test to caps unpacking
...
Pull cgroup changes from Tejun Heo:
"Out of the 8 commits, one fixes a long-standing locking issue around
tasklist walking and others are cleanups."
* 'for-3.4' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
cgroup: Walk task list under tasklist_lock in cgroup_enable_task_cg_list
cgroup: Remove wrong comment on cgroup_enable_task_cg_list()
cgroup: remove cgroup_subsys argument from callbacks
cgroup: remove extra calls to find_existing_css_set
cgroup: replace tasklist_lock with rcu_read_lock
cgroup: simplify double-check locking in cgroup_attach_proc
cgroup: move struct cgroup_pidlist out from the header file
cgroup: remove cgroup_attach_task_current_cg()
Pull scheduler changes for v3.4 from Ingo Molnar
* 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip: (27 commits)
printk: Make it compile with !CONFIG_PRINTK
sched/x86: Fix overflow in cyc2ns_offset
sched: Fix nohz load accounting -- again!
sched: Update yield() docs
printk/sched: Introduce special printk_sched() for those awkward moments
sched/nohz: Correctly initialize 'next_balance' in 'nohz' idle balancer
sched: Cleanup cpu_active madness
sched: Fix load-balance wreckage
sched: Clean up parameter passing of proc_sched_autogroup_set_nice()
sched: Ditch per cgroup task lists for load-balancing
sched: Rename load-balancing fields
sched: Move load-balancing arguments into helper struct
sched/rt: Do not submit new work when PI-blocked
sched/rt: Prevent idle task boosting
sched/wait: Add __wake_up_all_locked() API
sched/rt: Document scheduler related skip-resched-check sites
sched/rt: Use schedule_preempt_disabled()
sched/rt: Add schedule_preempt_disabled()
sched/rt: Do not throttle when PI boosting
sched/rt: Keep period timer ticking when rt throttling is active
...
This callback is called by the scheduler after rq->lock has been released
and interrupts enabled. It will be used in subsequent patches on the ARM
architecture.
Signed-off-by: Catalin Marinas <catalin.marinas@arm.com>
Reviewed-by: Will Deacon <will.deacon@arm.com>
Reviewed-by: Frank Rowand <frank.rowand@am.sony.com>
Tested-by: Will Deacon <will.deacon@arm.com>
Tested-by: Marc Zyngier <Marc.Zyngier@arm.com>
Acked-by: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/n/20120313110840.7b444deb6b1bb902c15f3cdf@canb.auug.org.au
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Various people reported nohz load tracking still being wrecked, but Doug
spotted the actual problem. We fold the nohz remainder in too soon,
causing us to loose samples and under-account.
So instead of playing catch-up up-front, always do a single load-fold
with whatever state we encounter and only then fold the nohz remainder
and play catch-up.
Reported-by: Doug Smythies <dsmythies@telus.net>
Reported-by: LesÅ=82aw Kope=C4=87 <leslaw.kopec@nasza-klasa.pl>
Reported-by: Aman Gupta <aman@tmm1.net>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/n/tip-4v31etnhgg9kwd6ocgx3rxl8@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@elte.hu>
There's a few awkward printk()s inside of scheduler guts that people
prefer to keep but really are rather deadlock prone. Fudge around it
by storing the text in a per-cpu buffer and poll it using the existing
printk_tick() handler.
This will drop output when its more frequent than once a tick, however
only the affinity thing could possible go that fast and for that just
one should suffice to notify the admin he's done something silly..
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Link: http://lkml.kernel.org/n/tip-wua3lmkt3dg8nfts66o6brne@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@elte.hu>
The 'next_balance' field of 'nohz' idle balancer must be initialized
to jiffies. Since jiffies is initialized to negative 300 seconds the
'nohz' idle balancer does not run for the first 300s (5mins) after
bootup. If no new processes are spawed or no idle cycles happen, the
load on the cpus will remain unbalanced for that duration.
Signed-off-by: Diwakar Tundlam <dtundlam@nvidia.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/1DD7BFEDD3147247B1355BEFEFE4665237994F30EF@HQMAIL04.nvidia.com
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Stepan found:
CPU0 CPUn
_cpu_up()
__cpu_up()
boostrap()
notify_cpu_starting()
set_cpu_online()
while (!cpu_active())
cpu_relax()
<PREEMPT-out>
smp_call_function(.wait=1)
/* we find cpu_online() is true */
arch_send_call_function_ipi_mask()
/* wait-forever-more */
<PREEMPT-in>
local_irq_enable()
cpu_notify(CPU_ONLINE)
sched_cpu_active()
set_cpu_active()
Now the purpose of cpu_active is mostly with bringing down a cpu, where
we mark it !active to avoid the load-balancer from moving tasks to it
while we tear down the cpu. This is required because we only update the
sched_domain tree after we brought the cpu-down. And this is needed so
that some tasks can still run while we bring it down, we just don't want
new tasks to appear.
On cpu-up however the sched_domain tree doesn't yet include the new cpu,
so its invisible to the load-balancer, regardless of the active state.
So instead of setting the active state after we boot the new cpu (and
consequently having to wait for it before enabling interrupts) set the
cpu active before we set it online and avoid the whole mess.
Reported-by: Stepan Moskovchenko <stepanm@codeaurora.org>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/r/1323965362.18942.71.camel@twins
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Commit 367456c ("sched: Ditch per cgroup task lists for
load-balancing") completely wrecked load-balancing due to
a few silly mistakes.
Correct those and remove more pointless code.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/n/tip-zk04ihygwxn7qqrlpaf73b0r@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@elte.hu>
This reverts commit 8f2f748b06.
It causes some odd regression that we have not figured out, and it's too
late in the -rc series to try to figure it out now.
As reported by Konstantin Khlebnikov, it causes consistent hangs on his
laptop (Thinkpad x220: 2x cores + HT). They can be avoided by adding
calls to "rebuild_sched_domains();" in cpuset_cpu_[in]active() for the
CPU_{ONLINE/DOWN_FAILED/DOWN_PREPARE}_FROZEN cases, but it's not at all
clear why, and it makes no sense.
Konstantin's config doesn't even have CONFIG_CPUSETS enabled, just to
make things even more interesting. So it's not the cpusets, it's just
the scheduling domains.
So until this is understood, revert.
Bisected-reported-and-tested-by: Konstantin Khlebnikov <khlebnikov@openvz.org>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Acked-by: Ingo Molnar <mingo@elte.hu>
Acked-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Pass nice as a value to proc_sched_autogroup_set_nice().
No side effect is expected, and the variable err will be overwritten with
the return value.
Signed-off-by: Hiroshi Shimamoto <h-shimamoto@ct.jp.nec.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/4F45FBB7.5090607@ct.jp.nec.com
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Per cgroup load-balance has numerous problems, chief amongst them that
there is no real sane order in them. So stop pretending it makes sense
and enqueue all tasks on a single list.
This also allows us to more easily fix the fwd progress issue
uncovered by the lock-break stuff. Rotate the list on failure to
migreate and limit the total iterations to nr_running (which with
releasing the lock isn't strictly accurate but close enough).
Also add a filter that skips very light tasks on the first attempt
around the list, this attempts to avoid shooting whole cgroups around
without affecting over balance.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: pjt@google.com
Link: http://lkml.kernel.org/n/tip-tx8yqydc7eimgq7i4rkc3a4g@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Passing large sets of similar arguments all around the load-balancer
gets tiresom when you want to modify something. Stick them all in a
helper structure and pass the structure around.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: pjt@google.com
Link: http://lkml.kernel.org/n/tip-5slqz0vhsdzewrfk9eza1aon@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@elte.hu>
When we are PI-blocked then we want to get things done ASAP.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/n/tip-vw8et3445km5b8mpihf4trae@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Idle task boosting is a nono in general. There is one
exception, when PREEMPT_RT and NOHZ is active:
The idle task calls get_next_timer_interrupt() and holds
the timer wheel base->lock on the CPU and another CPU wants
to access the timer (probably to cancel it). We can safely
ignore the boosting request, as the idle CPU runs this code
with interrupts disabled and will complete the lock
protected section without being interrupted. So there is no
real need to boost.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/n/tip-755rvsosz7sdzot12a3gbha6@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@elte.hu>
For code which protects the waitqueue itself with another lock it
makes no sense to acquire the waitqueue lock for wakeup all. Provide
__wake_up_all_locked().
This is an optimization on the vanilla kernel (to be used by the
PCI code) and an important semantic distinction on -rt.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/n/tip-ux6m4b8jonb9inx8xafh77ds@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Create a distinction between scheduler related preempt_enable_no_resched()
calls and the nearly one hundred other places in the kernel that do not
want to reschedule, for one reason or another.
This distinction matters for -rt, where the scheduler and the non-scheduler
preempt models (and checks) are different. For upstream it's purely
documentational.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/n/tip-gs88fvx2mdv5psnzxnv575ke@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Add helper to get rid of the ever repeating:
preempt_enable_no_resched();
schedule();
preempt_disable();
patterns.
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/n/tip-wxx7btox7coby6ifv5vzhzgp@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@elte.hu>
When a runqueue has rt_runtime_us = 0 then the only way it can
accumulate rt_time is via PI boosting. That causes the runqueue
to be throttled and replenishing does not change anything due to
rt_runtime_us = 0. So avoid that situation by clearing rt_time and
skip the throttling alltogether.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
[ Changelog ]
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/n/tip-7x70cypsotjb4jvcor3edctk@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@elte.hu>
When a runqueue is throttled we cannot disable the period timer
because that timer is the only way to undo the throttling.
We got stale throttling entries when a rq was throttled and then the
global sysctl was disabled, which stopped the timer.
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
[ Added changelog ]
Signed-off-by: Thomas Gleixner <tglx@linutronix.de>
Link: http://lkml.kernel.org/n/tip-nuj34q52p6ro7szapuz84i0v@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Currently, during CPU hotplug, the cpuset callbacks modify the cpusets
to reflect the state of the system, and this handling is asymmetric.
That is, upon CPU offline, that CPU is removed from all cpusets. However
when it comes back online, it is put back only to the root cpuset.
This gives rise to a significant problem during suspend/resume. During
suspend, we offline all non-boot cpus and during resume we online them back.
Which means, after a resume, all cpusets (except the root cpuset) will be
restricted to just one single CPU (the boot cpu). But the whole point of
suspend/resume is to restore the system to a state which is as close as
possible to how it was before suspend.
So to fix this, don't touch cpusets during suspend/resume. That is, modify
the cpuset-related CPU hotplug callback to just ignore CPU hotplug when it
is initiated as part of the suspend/resume sequence.
Reported-by: Prashanth Nageshappa <prashanth@linux.vnet.ibm.com>
Signed-off-by: Srivatsa S. Bhat <srivatsa.bhat@linux.vnet.ibm.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: stable@vger.kernel.org
Link: http://lkml.kernel.org/r/4F460D7B.1020703@linux.vnet.ibm.com
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Ingo Molnar <mingo@elte.hu>
So here's a boot tested patch on top of Jason's series that does
all the cleanups I talked about and turns jump labels into a
more intuitive to use facility. It should also address the
various misconceptions and confusions that surround jump labels.
Typical usage scenarios:
#include <linux/static_key.h>
struct static_key key = STATIC_KEY_INIT_TRUE;
if (static_key_false(&key))
do unlikely code
else
do likely code
Or:
if (static_key_true(&key))
do likely code
else
do unlikely code
The static key is modified via:
static_key_slow_inc(&key);
...
static_key_slow_dec(&key);
The 'slow' prefix makes it abundantly clear that this is an
expensive operation.
I've updated all in-kernel code to use this everywhere. Note
that I (intentionally) have not pushed through the rename
blindly through to the lowest levels: the actual jump-label
patching arch facility should be named like that, so we want to
decouple jump labels from the static-key facility a bit.
On non-jump-label enabled architectures static keys default to
likely()/unlikely() branches.
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Acked-by: Jason Baron <jbaron@redhat.com>
Acked-by: Steven Rostedt <rostedt@goodmis.org>
Cc: a.p.zijlstra@chello.nl
Cc: mathieu.desnoyers@efficios.com
Cc: davem@davemloft.net
Cc: ddaney.cavm@gmail.com
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/20120222085809.GA26397@elte.hu
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Current the initial SCHED_RR timeslice of init_task is HZ, which means
1s, and is not same as the default SCHED_RR timeslice DEF_TIMESLICE.
Change that initial timeslice to the DEF_TIMESLICE.
Signed-off-by: Hiroshi Shimamoto <h-shimamoto@ct.jp.nec.com>
[ s/DEF_TIMESLICE/RR_TIMESLICE/g ]
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/4F3C9995.3010800@ct.jp.nec.com
Signed-off-by: Ingo Molnar <mingo@elte.hu>
select_idle_sibling() is called from select_task_rq_fair(), which
already has the RCU read lock held.
Signed-off-by: Nikunj A. Dadhania <nikunj@linux.vnet.ibm.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/20120217030409.11748.12491.stgit@abhimanyu
Signed-off-by: Ingo Molnar <mingo@elte.hu>
Commit 1ac9bc69 ("sched/tracing: Add a new tracepoint for sleeptime")
added a new sched:sched_stat_sleeptime tracepoint.
It's broken: the first sample we get on a task might be bad because
of a stale sleep_start value that wasn't reset at the last task switch
because the tracepoint was not active.
It also breaks the existing schedstat samples due to the side
effects of:
- se->statistics.sleep_start = 0;
...
- se->statistics.block_start = 0;
Nor do I see means to fix it without adding overhead to the scheduler
fast path, which I'm not willing to for the sake of redundant
instrumentation.
Most importantly, sleep time information can already be constructed
by tracing context switches and wakeups, and taking the timestamp
difference between the schedule-out, the wakeup and the schedule-in.
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Andrew Vagin <avagin@openvz.org>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Link: http://lkml.kernel.org/n/tip-pc4c9qhl8q6vg3bs4j6k0rbd@git.kernel.org
Signed-off-by: Ingo Molnar <mingo@elte.hu>
The argument is not used at all, and it's not necessary, because
a specific callback handler of course knows which subsys it
belongs to.
Now only ->pupulate() takes this argument, because the handlers of
this callback always call cgroup_add_file()/cgroup_add_files().
So we reduce a few lines of code, though the shrinking of object size
is minimal.
16 files changed, 113 insertions(+), 162 deletions(-)
text data bss dec hex filename
5486240 656987 7039960 13183187 c928d3 vmlinux.o.orig
5486170 656987 7039960 13183117 c9288d vmlinux.o
Signed-off-by: Li Zefan <lizf@cn.fujitsu.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
