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  1. 13 12月, 2008 1 次提交
    • R
      cpumask: change cpumask_scnprintf, cpumask_parse_user, cpulist_parse, and... · 29c0177e
      由 Rusty Russell 提交于 
      cpumask: change cpumask_scnprintf, cpumask_parse_user, cpulist_parse, and cpulist_scnprintf to take pointers.

Impact: change calling convention of existing cpumask APIs

Most cpumask functions started with cpus_: these have been replaced by
cpumask_ ones which take struct cpumask pointers as expected.

These four functions don't have good replacement names; fortunately
they're rarely used, so we just change them over.
Signed-off-by: NRusty Russell <rusty@rustcorp.com.au>
Signed-off-by: NMike Travis <travis@sgi.com>
Acked-by: NIngo Molnar <mingo@elte.hu>
Cc: paulus@samba.org
Cc: mingo@redhat.com
Cc: tony.luck@intel.com
Cc: ralf@linux-mips.org
Cc: Greg Kroah-Hartman <gregkh@suse.de>
Cc: cl@linux-foundation.org
Cc: srostedt@redhat.com
      29c0177e
  3. 12 12月, 2008 2 次提交
  5. 10 12月, 2008 1 次提交
    • B
      sched: CPU remove deadlock fix · 9a2bd244
      由 Brian King 提交于 
      Impact: fix possible deadlock in CPU hot-remove path

This patch fixes a possible deadlock scenario in the CPU remove path.
migration_call grabs rq->lock, then wakes up everything on rq->migration_queue
with the lock held. Then one of the tasks on the migration queue ends up
calling tg_shares_up which then also tries to acquire the same rq->lock.

[c000000058eab2e0] c000000000502078 ._spin_lock_irqsave+0x98/0xf0
[c000000058eab370] c00000000008011c .tg_shares_up+0x10c/0x20c
[c000000058eab430] c00000000007867c .walk_tg_tree+0xc4/0xfc
[c000000058eab4d0] c0000000000840c8 .try_to_wake_up+0xb0/0x3c4
[c000000058eab590] c0000000000799a0 .__wake_up_common+0x6c/0xe0
[c000000058eab640] c00000000007ada4 .complete+0x54/0x80
[c000000058eab6e0] c000000000509fa8 .migration_call+0x5fc/0x6f8
[c000000058eab7c0] c000000000504074 .notifier_call_chain+0x68/0xe0
[c000000058eab860] c000000000506568 ._cpu_down+0x2b0/0x3f4
[c000000058eaba60] c000000000506750 .cpu_down+0xa4/0x108
[c000000058eabb10] c000000000507e54 .store_online+0x44/0xa8
[c000000058eabba0] c000000000396260 .sysdev_store+0x3c/0x50
[c000000058eabc10] c0000000001a39b8 .sysfs_write_file+0x124/0x18c
[c000000058eabcd0] c00000000013061c .vfs_write+0xd0/0x1bc
[c000000058eabd70] c0000000001308a4 .sys_write+0x68/0x114
[c000000058eabe30] c0000000000086b4 syscall_exit+0x0/0x40
Signed-off-by: NBrian King <brking@linux.vnet.ibm.com>
Acked-by: NPeter Zijlstra <peterz@infradead.org>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
      9a2bd244
  7. 08 12月, 2008 2 次提交
  9. 02 12月, 2008 1 次提交
  11. 30 11月, 2008 1 次提交
    • I
      sched: prevent divide by zero error in cpu_avg_load_per_task, update · af6d596f
      由 Ingo Molnar 提交于 
      Regarding the bug addressed in:

  4cd42620: sched: prevent divide by zero error in cpu_avg_load_per_task

Linus points out that the fix is not complete:

> There's nothing that keeps gcc from deciding not to reload
> rq->nr_running.
>
> Of course, in _practice_, I don't think gcc ever will (if it decides
> that it will spill, gcc is likely going to decide that it will
> literally spill the local variable to the stack rather than decide to
> reload off the pointer), but it's a valid compiler optimization, and
> it even has a name (rematerialization).
>
> So I suspect that your patch does fix the bug, but it still leaves the
> fairly unlikely _potential_ for it to re-appear at some point.
>
> We have ACCESS_ONCE() as a macro to guarantee that the compiler
> doesn't rematerialize a pointer access. That also would clarify
> the fact that we access something unsafe outside a lock.

So make sure our nr_running value is immutable and cannot change
after we check it for nonzero.
Signed-off-by: NIngo Molnar <mingo@elte.hu>
      af6d596f
  13. 29 11月, 2008 1 次提交
    • A
      sched: move double_unlock_balance() higher · 70574a99
      由 Alexey Dobriyan 提交于 
      Move double_lock_balance()/double_unlock_balance() higher to fix the following
with gcc-3.4.6:

   CC      kernel/sched.o
 In file included from kernel/sched.c:1605:
 kernel/sched_rt.c: In function `find_lock_lowest_rq':
 kernel/sched_rt.c:914: sorry, unimplemented: inlining failed in call to 'double_unlock_balance': function body not available
 kernel/sched_rt.c:1077: sorry, unimplemented: called from here
 make[2]: *** [kernel/sched.o] Error 1
Signed-off-by: NAlexey Dobriyan <adobriyan@gmail.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
      70574a99
  15. 27 11月, 2008 1 次提交
    • S
      sched: prevent divide by zero error in cpu_avg_load_per_task · 4cd42620
      由 Steven Rostedt 提交于 
      Impact: fix divide by zero crash in scheduler rebalance irq

While testing the branch profiler, I hit this crash:

divide error: 0000 [#1] PREEMPT SMP
[...]
RIP: 0010:[<ffffffff8024a008>]  [<ffffffff8024a008>] cpu_avg_load_per_task+0x50/0x7f
[...]
Call Trace:
 <IRQ> <0> [<ffffffff8024fd43>] find_busiest_group+0x3e5/0xcaa
 [<ffffffff8025da75>] rebalance_domains+0x2da/0xa21
 [<ffffffff80478769>] ? find_next_bit+0x1b2/0x1e6
 [<ffffffff8025e2ce>] run_rebalance_domains+0x112/0x19f
 [<ffffffff8026d7c2>] __do_softirq+0xa8/0x232
 [<ffffffff8020ea7c>] call_softirq+0x1c/0x3e
 [<ffffffff8021047a>] do_softirq+0x94/0x1cd
 [<ffffffff8026d5eb>] irq_exit+0x6b/0x10e
 [<ffffffff8022e6ec>] smp_apic_timer_interrupt+0xd3/0xff
 [<ffffffff8020e4b3>] apic_timer_interrupt+0x13/0x20

The code for cpu_avg_load_per_task has:

	if (rq->nr_running)
		rq->avg_load_per_task = rq->load.weight / rq->nr_running;

The runqueue lock is not held here, and there is nothing that prevents
the rq->nr_running from going to zero after it passes the if condition.

The branch profiler simply made the race window bigger.

This patch saves off the rq->nr_running to a local variable and uses that
for both the condition and the division.
Signed-off-by: NSteven Rostedt <srostedt@redhat.com>
Peter Zijlstra <peterz@infradead.org>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
      4cd42620
  17. 26 11月, 2008 3 次提交
  19. 25 11月, 2008 20 次提交
  21. 23 11月, 2008 2 次提交
  23. 21 11月, 2008 1 次提交
    • V
      sched: update comment for move_task_off_dead_cpu · 957ad016
      由 Vegard Nossum 提交于 
      Impact: cleanup

This commit:

commit f7b4cddc
Author: Oleg Nesterov <oleg@tv-sign.ru>
Date:   Tue Oct 16 23:30:56 2007 -0700

    do CPU_DEAD migrating under read_lock(tasklist) instead of write_lock_irq(ta

    Currently move_task_off_dead_cpu() is called under
    write_lock_irq(tasklist).  This means it can't use task_lock() which is
    needed to improve migrating to take task's ->cpuset into account.

    Change the code to call move_task_off_dead_cpu() with irqs enabled, and
    change migrate_live_tasks() to use read_lock(tasklist).

...forgot to update the comment in front of move_task_off_dead_cpu.

Reference: http://lkml.org/lkml/2008/6/23/135Signed-off-by: NVegard Nossum <vegard.nossum@gmail.com>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
      957ad016
  25. 20 11月, 2008 1 次提交
    • K
      sched: fix inconsistency when redistribute per-cpu tg->cfs_rq shares · ec4e0e2f
      由 Ken Chen 提交于 
      Impact: make load-balancing more consistent

In the update_shares() path leading to tg_shares_up(), the calculation of
per-cpu cfs_rq shares is rather erratic even under moderate task wake up
rate.  The problem is that the per-cpu tg->cfs_rq load weight used in the
sd_rq_weight aggregation and actual redistribution of the cfs_rq->shares
are collected at different time.  Under moderate system load, we've seen
quite a bit of variation on the cfs_rq->shares and ultimately wildly
affects sched_entity's load weight.

This patch caches the result of initial per-cpu load weight when doing the
sum calculation, and then pass it down to update_group_shares_cpu() for
redistributing per-cpu cfs_rq shares.  This allows consistent total cfs_rq
shares across all CPUs. It also simplifies the rounding and zero load
weight check.
Signed-off-by: NKen Chen <kenchen@google.com>
Acked-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
      ec4e0e2f
  27. 18 11月, 2008 1 次提交
    • L
      cpuset: fix regression when failed to generate sched domains · 700018e0
      由 Li Zefan 提交于 
      Impact: properly rebuild sched-domains on kmalloc() failure

When cpuset failed to generate sched domains due to kmalloc()
failure, the scheduler should fallback to the single partition
'fallback_doms' and rebuild sched domains, but now it only
destroys but not rebuilds sched domains.

The regression was introduced by:

| commit dfb512ec
| Author: Max Krasnyansky <maxk@qualcomm.com>
| Date:   Fri Aug 29 13:11:41 2008 -0700
|
|    sched: arch_reinit_sched_domains() must destroy domains to force rebuild

After the above commit, partition_sched_domains(0, NULL, NULL) will
only destroy sched domains and partition_sched_domains(1, NULL, NULL)
will create the default sched domain.
Signed-off-by: NLi Zefan <lizf@cn.fujitsu.com>
Cc: Max Krasnyansky <maxk@qualcomm.com>
Cc: <stable@kernel.org>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
      700018e0
  29. 17 11月, 2008 1 次提交
  31. 16 11月, 2008 1 次提交
    • M
      tracepoints: add DECLARE_TRACE() and DEFINE_TRACE() · 7e066fb8
      由 Mathieu Desnoyers 提交于 
      Impact: API *CHANGE*. Must update all tracepoint users.

Add DEFINE_TRACE() to tracepoints to let them declare the tracepoint
structure in a single spot for all the kernel. It helps reducing memory
consumption, especially when declaring a lot of tracepoints, e.g. for
kmalloc tracing.

*API CHANGE WARNING*: now, DECLARE_TRACE() must be used in headers for
tracepoint declarations rather than DEFINE_TRACE(). This is the sane way
to do it. The name previously used was misleading.

Updates scheduler instrumentation to follow this API change.
Signed-off-by: NMathieu Desnoyers <mathieu.desnoyers@polymtl.ca>
Signed-off-by: NIngo Molnar <mingo@elte.hu>
      7e066fb8