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  1. 31 8月, 2011 2 次提交
    • A
      x86, perf: Check that current->mm is alive before getting user callchain · 20afc60f
      由 Andrey Vagin 提交于 
      An event may occur when an mm is already released.

I added an event in dequeue_entity() and caught a panic with
the following backtrace:

[  434.421110] BUG: unable to handle kernel NULL pointer dereference at 0000000000000050
[  434.421258] IP: [<ffffffff810464ac>] __get_user_pages_fast+0x9c/0x120
...
[  434.421258] Call Trace:
[  434.421258]  [<ffffffff8101ae81>] copy_from_user_nmi+0x51/0xf0
[  434.421258]  [<ffffffff8109a0d5>] ? sched_clock_local+0x25/0x90
[  434.421258]  [<ffffffff8101b048>] perf_callchain_user+0x128/0x170
[  434.421258]  [<ffffffff811154cd>] ? __perf_event_header__init_id+0xed/0x100
[  434.421258]  [<ffffffff81116690>] perf_prepare_sample+0x200/0x280
[  434.421258]  [<ffffffff81118da8>] __perf_event_overflow+0x1b8/0x290
[  434.421258]  [<ffffffff81065240>] ? tg_shares_up+0x0/0x670
[  434.421258]  [<ffffffff8104fe1a>] ? walk_tg_tree+0x6a/0xb0
[  434.421258]  [<ffffffff81118f44>] perf_swevent_overflow+0xc4/0xf0
[  434.421258]  [<ffffffff81119150>] do_perf_sw_event+0x1e0/0x250
[  434.421258]  [<ffffffff81119204>] perf_tp_event+0x44/0x70
[  434.421258]  [<ffffffff8105701f>] ftrace_profile_sched_block+0xdf/0x110
[  434.421258]  [<ffffffff8106121d>] dequeue_entity+0x2ad/0x2d0
[  434.421258]  [<ffffffff810614ec>] dequeue_task_fair+0x1c/0x60
[  434.421258]  [<ffffffff8105818a>] dequeue_task+0x9a/0xb0
[  434.421258]  [<ffffffff810581e2>] deactivate_task+0x42/0xe0
[  434.421258]  [<ffffffff814bc019>] thread_return+0x191/0x808
[  434.421258]  [<ffffffff81098a44>] ? switch_task_namespaces+0x24/0x60
[  434.421258]  [<ffffffff8106f4c4>] do_exit+0x464/0x910
[  434.421258]  [<ffffffff8106f9c8>] do_group_exit+0x58/0xd0
[  434.421258]  [<ffffffff8106fa57>] sys_exit_group+0x17/0x20
[  434.421258]  [<ffffffff8100b202>] system_call_fastpath+0x16/0x1b
Signed-off-by: NAndrey Vagin <avagin@openvz.org>
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Cc: stable@kernel.org
Link: http://lkml.kernel.org/r/1314693156-24131-1-git-send-email-avagin@openvz.orgSigned-off-by: NIngo Molnar <mingo@elte.hu>
      20afc60f
    • E
      perf_event: Fix broken calc_timer_values() · 7f310a5d
      由 Eric B Munson 提交于 
      We detected a serious issue with PERF_SAMPLE_READ and
timing information when events were being multiplexing.

Samples would have time_running > time_enabled. That
was easy to reproduce with a libpfm4 example (ran 3
times to cause multiplexing on Core 2):

 $ syst_smpl -e uops_retired:freq=1 &
 $ syst_smpl -e uops_retired:freq=1 &
 $ syst_smpl -e uops_retired:freq=1 &
 IIP:0x0000000040062d ... PERIOD:2355332948 ENA=40144625315 RUN=60014875184
 syst_smpl: WARNING: time_running > time_enabled
	63277537998 uops_retired:freq=1 , scaled

The bug was not present in kernel up to (and including) 3.0. It turns
out the bug was introduced by the following commit:

commit c4794295

    events: Move lockless timer calculation into helper function

The parameters of the function got reversed yet the call sites
were not updated to reflect the change. That lead to time_running
and time_enabled being swapped. That had no effect when there was
no multiplexing because in that case time_running = time_enabled
but it would show up in any other scenario.
Signed-off-by: NStephane Eranian <eranian@google.com>
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/20110829124112.GA4828@quadSigned-off-by: NIngo Molnar <mingo@elte.hu>
      7f310a5d
  3. 29 8月, 2011 3 次提交
    • S
      perf events: Fix slow and broken cgroup context switch code · a8d757ef
      由 Stephane Eranian 提交于 
      The current cgroup context switch code was incorrect leading
to bogus counts. Furthermore, as soon as there was an active
cgroup event on a CPU, the context switch cost on that CPU
would increase by a significant amount as demonstrated by a
simple ping/pong example:

 $ ./pong
 Both processes pinned to CPU1, running for 10s
 10684.51 ctxsw/s

Now start a cgroup perf stat:
 $ perf stat -e cycles,cycles -A -a -G test  -C 1 -- sleep 100

$ ./pong
 Both processes pinned to CPU1, running for 10s
 6674.61 ctxsw/s

That's a 37% penalty.

Note that pong is not even in the monitored cgroup.

The results shown by perf stat are bogus:
 $ perf stat -e cycles,cycles -A -a -G test  -C 1 -- sleep 100

 Performance counter stats for 'sleep 100':

 CPU1 <not counted> cycles   test
 CPU1 16,984,189,138 cycles  #    0.000 GHz

The second 'cycles' event should report a count @ CPU clock
(here 2.4GHz) as it is counting across all cgroups.

The patch below fixes the bogus accounting and bypasses any
cgroup switches in case the outgoing and incoming tasks are
in the same cgroup.

With this patch the same test now yields:
 $ ./pong
 Both processes pinned to CPU1, running for 10s
 10775.30 ctxsw/s

Start perf stat with cgroup:

 $ perf stat -e cycles,cycles -A -a -G test  -C 1 -- sleep 10

Run pong outside the cgroup:
 $ /pong
 Both processes pinned to CPU1, running for 10s
 10687.80 ctxsw/s

The penalty is now less than 2%.

And the results for perf stat are correct:

$ perf stat -e cycles,cycles -A -a -G test  -C 1 -- sleep 10

 Performance counter stats for 'sleep 10':

 CPU1 <not counted> cycles test #    0.000 GHz
 CPU1 23,933,981,448 cycles      #    0.000 GHz

Now perf stat reports the correct counts for
for the non cgroup event.

If we run pong inside the cgroup, then we also get the
correct counts:

$ perf stat -e cycles,cycles -A -a -G test  -C 1 -- sleep 10

 Performance counter stats for 'sleep 10':

 CPU1 22,297,726,205 cycles test #    0.000 GHz
 CPU1 23,933,981,448 cycles      #    0.000 GHz

      10.001457237 seconds time elapsed
Signed-off-by: NStephane Eranian <eranian@google.com>
Signed-off-by: NPeter Zijlstra <a.p.zijlstra@chello.nl>
Link: http://lkml.kernel.org/r/20110825135803.GA4697@quadSigned-off-by: NIngo Molnar <mingo@elte.hu>
      a8d757ef
    • L
      Linux 3.1-rc4 · c6a389f1
      由 Linus Torvalds 提交于
      c6a389f1
    • L
      Merge branch 'pm-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm · c11a7e26
      由 Linus Torvalds 提交于 
      * 'pm-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/rafael/linux-pm:
  ARM: mach-shmobile: sh7372 LCDC1 suspend fix V2 (incremental)
  OMAP: omap_device: only override _noirq methods, not normal suspend/resume
  PM / Runtime: Correct documentation of pm_runtime_irq_safe()
  ARM: mach-shmobile: sh7372 LCDC1 suspend fix
  sh-sci / PM: Use power.irq_safe
  PM: Use spinlock instead of mutex in clock management functions
      c11a7e26
  5. 28 8月, 2011 1 次提交
  7. 27 8月, 2011 10 次提交
  9. 26 8月, 2011 24 次提交