Skip to content

L
linux
Switch branch/tag
  1. 20 Jul, 2017 2 commits
    • Ingo Molnar's avatar
      Merge tag 'perf-core-for-mingo-4.13-20170718' of... · 510457ec
      Ingo Molnar authored 
      Merge tag 'perf-core-for-mingo-4.13-20170718' of git://git.kernel.org/pub/scm/linux/kernel/git/acme/linux into perf/core

Pull perf/core improvements and fixes from Arnaldo Carvalho de Melo:

User visible changes:

- Initial support for namespaces, using setns to access files in
  namespaces, grabbing their build-ids, etc. We still need to work
  more to deal with namespaces that vanish before we can get the
  needed data to do analysis, but this should be as good as what is
  in bcc now (Krister Johansen)

- Add header record types to pipe-mode, now this command:

  $ perf record -o - -e cycles sleep 1 | perf report --stdio --header

  Will show the same as in non-pipe mode, i.e. involving a perf.data
  file (David Carrillo-Cisneros)

- Implement a visual marker for fused x86 instructions in the annotate
  TUI browser, available now in 'perf report', more work needed to have
  it available as well in 'perf top' (Jin Yao)

  Further explanation from one of Jin's patches:

       │   ┌──cmpl   $0x0,argp_program_version_hook
 81.93 │   ├──je     20
       │   │  lock   cmpxchg %esi,0x38a9a4(%rip)
       │   │↓ jne    29
       │   │↓ jmp    43
 11.47 │20:└─→cmpxch %esi,0x38a999(%rip)

  That means the cmpl+je is a fused instruction pair and they should be
  considered together.

- Record the branch type and then show statistics and info about
  in callchain entries (Jin Yao)

  Example from one of Jin's patches:

  # perf record -g -j any,save_type
  # perf report --branch-history --stdio --no-children

  38.50%  div.c:45                [.] main                    div
          |
          ---main div.c:42 (RET CROSS_2M cycles:2)
             compute_flag div.c:28 (cycles:2)
             compute_flag div.c:27 (RET CROSS_2M cycles:1)
             rand rand.c:28 (cycles:1)
             rand rand.c:28 (RET CROSS_2M cycles:1)
             __random random.c:298 (cycles:1)
             __random random.c:297 (COND_BWD CROSS_2M cycles:1)
             __random random.c:295 (cycles:1)
             __random random.c:295 (COND_BWD CROSS_2M cycles:1)
             __random random.c:295 (cycles:1)
             __random random.c:295 (RET CROSS_2M cycles:9)

- Beautify the fcntl syscall, which is an interesting one in the sense
  that infrastructure had to be put in place to change the formatters of
  some arguments according to the value in a previous one, i.e. cmd
  dictates how arg and the syscall return will be formatted.
  (Arnaldo Carvalho de Melo

Infrastructure changes:

- 'perf test attr' fixes (Jiri Olsa)

Vendor events changes:

- Add POWER9 PMU events Sukadev (Bhattiprolu)

- Support additional POWER8+ PVR in PMU mapfile (Shriya)
Signed-off-by: default avatarArnaldo Carvalho de Melo <acme@redhat.com>
Signed-off-by: default avatarIngo Molnar <mingo@kernel.org>
      510457ec
    • Alexander Shishkin's avatar
      perf/core: Fix scheduling regression of pinned groups · 3bda69c1
      Alexander Shishkin authored 
      Vince Weaver reported:

> I was tracking down some regressions in my perf_event_test testsuite.
> Some of the tests broke in the 4.11-rc1 timeframe.
>
> I've bisected one of them, this report is about
>	tests/overflow/simul_oneshot_group_overflow
> This test creates an event group containing two sampling events, set
> to overflow to a signal handler (which disables and then refreshes the
> event).
>
> On a good kernel you get the following:
> 	Event perf::instructions with period 1000000
> 	Event perf::instructions with period 2000000
> 		fd 3 overflows: 946 (perf::instructions/1000000)
> 		fd 4 overflows: 473 (perf::instructions/2000000)
> 	Ending counts:
> 		Count 0: 946379875
> 		Count 1: 946365218
>
> With the broken kernels you get:
> 	Event perf::instructions with period 1000000
> 	Event perf::instructions with period 2000000
> 		fd 3 overflows: 938 (perf::instructions/1000000)
> 		fd 4 overflows: 318 (perf::instructions/2000000)
> 	Ending counts:
> 		Count 0: 946373080
> 		Count 1: 653373058

The root cause of the bug is that the following commit:

  487f05e1 ("perf/core: Optimize event rescheduling on active contexts")

erronously assumed that event's 'pinned' setting determines whether the
event belongs to a pinned group or not, but in fact, it's the group
leader's pinned state that matters.

This was discovered by Vince in the test case described above, where two instruction
counters are grouped, the group leader is pinned, but the other event is not;
in the regressed case the counters were off by 33% (the difference between events'
periods), but should be the same within the error margin.

Fix the problem by looking at the group leader's pinning.
Reported-by: default avatarVince Weaver <vincent.weaver@maine.edu>
Tested-by: default avatarVince Weaver <vincent.weaver@maine.edu>
Signed-off-by: default avatarAlexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@gmail.com>
Cc: Thomas Gleixner <tglx@linutronix.de>
Cc: stable@vger.kernel.org
Fixes: 487f05e1 ("perf/core: Optimize event rescheduling on active contexts")
Link: http://lkml.kernel.org/r/87lgnmvw7h.fsf@ashishki-desk.ger.corp.intel.comSigned-off-by: default avatarIngo Molnar <mingo@kernel.org>
      3bda69c1
  3. 19 Jul, 2017 38 commits
GitLab Nexedi Edition | About GitLab | About Nexedi | 沪ICP备2021021310号-2 | 沪ICP备2021021310号-7