linux-kernel - [PATCH v1 0/3] perf: expose thread context switch out event type to user space

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Message-ID: <6db586f3-36da-285c-b008-f2722419fbf8@linux.intel.com>
Date:   Mon, 5 Mar 2018 14:35:02 +0300
From:   Alexey Budankov <alexey.budankov@...ux.intel.com>
To:     Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>
Cc:     Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...hat.com>,
        Namhyung Kim <namhyung@...nel.org>,
        Andi Kleen <ak@...ux.intel.com>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        Dmitri Prokhorov <Dmitry.Prohorov@...el.com>
Subject: [PATCH v1 0/3] perf: expose thread context switch out event type to
 user space


Here is a series of small patches that implement exposing type of 
context-switch-out event as a part of PERF_RECORD_SWITCH[_CPU_WIDE] record.

Introduced types of context-switch-out events assumed to be:
a) preempt: task->state == TASK_RUNNING
	misc &= PERF_RECORD_MISC_SWITCH_OUT
	
b) yield: !preempt - using new bit PERF_RECORD_MISC_SWITCH_OUT_YIELD:
	misc &= PERF_RECORD_MISC_SWITCH_OUT|PERF_RECORD_MISC_SWITCH_OUT_YIELD

Perf tool report and script commands output has been extended to decode 
new yield bit and the updated output looks like in the examples below.

The documentation has been updated to mention yield switch out events and its 
decoding symbols in perf script output.

The changes have been manually tested on Fedora 27 with the patched kernel:
git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip.git perf/core

perf report -D -i system-wide.perf: 

0x1b9c50 [0x30]: event: 15
.
. ... raw event: size 48 bytes
.  0000:  0f 00 00 00 00 20 30 00 01 1e 00 00 01 1e 00 00  ..... 0.........
.  0010:  00 00 00 00 00 00 00 00 85 ae d4 e3 3e 0e 00 00  ............>...
.  0020:  54 00 00 00 00 00 00 00 05 00 00 00 00 00 00 00  T...............

5 15663273127557 0x1b9c50 [0x30]: PERF_RECORD_SWITCH_CPU_WIDE OUT  next pid/tid:  7681/7681 

0x2646c0 [0x30]: event: 15
.
. ... raw event: size 48 bytes
.  0000:  0f 00 00 00 00 60 30 00 00 00 00 00 00 00 00 00  .....`0.........
.  0010:  00 1e 00 00 00 1e 00 00 29 1e d5 e3 3e 0e 00 00  ........)...>...
.  0020:  56 00 00 00 00 00 00 00 07 00 00 00 00 00 00 00  V...............

7 15663273156137 0x2646c0 [0x30]: PERF_RECORD_SWITCH_CPU_WIDE OUT yield  next pid/tid:     0/0

perf script --show-switch-events -F +misc -I -i system-wide.perf:

amplxe-perf  7681 [005] S     15663.273151: PERF_RECORD_SWITCH_CPU_WIDE OUT  next pid/tid:    39/39   
migration/5    39 [005]       15663.273152: PERF_RECORD_SWITCH_CPU_WIDE IN   prev pid/tid:  7681/7681 
amplxe-perf  7680 [007] K     15663.273153:          1                                                                                                                                       context-switch: 
                  aaa488 schedule ([kernel.kallsyms])
                  1a9f50 __poll_nocancel (inlined)

amplxe-perf  7680 [007] Sy    15663.273156: PERF_RECORD_SWITCH_CPU_WIDE OUT yield  next pid/tid:     0/0    
migration/5    39 [005] K     15663.273157:

---
 Alexey Budankov (3):
	perf/core: store context switch out type into Perf trace
	perf report: extend raw dump (-D) out with switch out event type
	perf script: extend misc field decoding with switch out event type
  
 include/uapi/linux/perf_event.h          |  5 +++++
 kernel/events/core.c                     |  4 +++-
 tools/include/uapi/linux/perf_event.h    |  5 +++++
 tools/perf/Documentation/perf-script.txt | 17 +++++++++--------
 tools/perf/builtin-script.c              |  5 ++++-
 tools/perf/util/event.c                  |  4 +++-
 6 files changed, 29 insertions(+), 11 deletions(-)