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Subject[PATCH v3 0/3] perf/core: expose thread context switch out event type to user space
Date

Implementation of exposing context-switch-out type event as a part
of PERF_RECORD_SWITCH[_CPU_WIDE] record.

Introduced types of events assumed to be:

a) preempt: when task->state == TASK_RUNNING, encoding is implemented using
new PERF_RECORD_MISC_SWITCH_OUT_PREEMPT bit
event_header->misc &=
PERF_RECORD_MISC_SWITCH_OUT|PERF_RECORD_MISC_SWITCH_OUT_PREEMPT

b) !preempt: encoding is implemented the only PERF_RECORD_MISC_SWITCH_OUT bit
event_header->misc &= PERF_RECORD_MISC_SWITCH_OUT

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

The documentation has been updated to mention PREEMPT 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

tools/perf/perf report -D -i perf.data | grep _SWITCH

0 768361415226 0x27f076 [0x28]: PERF_RECORD_SWITCH_CPU_WIDE IN prev pid/tid: 8/8
4 768362216813 0x28f45e [0x28]: PERF_RECORD_SWITCH_CPU_WIDE OUT next pid/tid: 0/0
4 768362217824 0x28f486 [0x28]: PERF_RECORD_SWITCH_CPU_WIDE IN prev pid/tid: 4073/4073
0 768362414027 0x27f0ce [0x28]: PERF_RECORD_SWITCH_CPU_WIDE OUT preempt next pid/tid: 8/8
0 768362414367 0x27f0f6 [0x28]: PERF_RECORD_SWITCH_CPU_WIDE IN prev pid/tid: 0/0

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

hdparm 4073 [004] U 762.198265: 380194 cycles:ppp: 7faf727f5a23 strchr (/usr/lib64/ld-2.26.so)
hdparm 4073 [004] K 762.198366: 441572 cycles:ppp: ffffffffb9218435 alloc_set_pte (/lib/modules/4.16.0-rc6+/build/vmlinux)
hdparm 4073 [004] S 762.198391: PERF_RECORD_SWITCH_CPU_WIDE OUT next pid/tid: 0/0
swapper 0 [004] 762.198392: PERF_RECORD_SWITCH_CPU_WIDE IN prev pid/tid: 4073/4073
swapper 0 [004] Sp 762.198477: PERF_RECORD_SWITCH_CPU_WIDE OUT preempt next pid/tid: 4073/4073
hdparm 4073 [004] 762.198478: PERF_RECORD_SWITCH_CPU_WIDE IN prev pid/tid: 0/0
swapper 0 [007] K 762.198514: 2303073 cycles:ppp: ffffffffb98b0c66 intel_idle (/lib/modules/4.16.0-rc6+/build/vmlinux)
swapper 0 [007] Sp 762.198561: PERF_RECORD_SWITCH_CPU_WIDE OUT preempt next pid/tid: 1134/1134
kworker/u16:18 1134 [007] 762.198562: PERF_RECORD_SWITCH_CPU_WIDE IN prev pid/tid: 0/0
kworker/u16:18 1134 [007] S 762.198567: PERF_RECORD_SWITCH_CPU_WIDE OUT next pid/tid: 0/0

---
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 | 4 ++++
kernel/events/core.c | 4 +++-
tools/include/uapi/linux/perf_event.h | 4 ++++
tools/perf/Documentation/perf-script.txt | 17 +++++++++--------
tools/perf/builtin-script.c | 5 ++++-
tools/perf/util/event.c | 4 +++-
6 files changed, 27 insertions(+), 11 deletions(-)


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