| Message ID | 20220811185456.194721-1-namhyung@kernel.org (mailing list archive) |
|---|---|
| Headers | show |
| Series | Track processes properly for perf record --off-cpu (v2) | expand |
Em Thu, Aug 11, 2022 at 11:54:52AM -0700, Namhyung Kim escreveu: > Hello, > > This patch series implements inheritance of offcpu events for the > child processes. Unlike perf events, BPF cannot know which task it > should track except for ones set in a BPF map at the beginning. Add > another BPF program to the fork path and add the process id to the map > if the parent is tracked. Thanks for resubmitting, applied! Will be up in perf/core as soon as tests finish. - Arnaldo > Changes in v2) > * drop already merged fixes > * fix the shell test to omit noises > > With this change, it can get the correct off-cpu events for child > processes. I've tested it with perf bench sched messaging which > creates a lot of processes. > > $ sudo perf record -e dummy --off-cpu -- perf bench sched messaging > # Running 'sched/messaging' benchmark: > # 20 sender and receiver processes per group > # 10 groups == 400 processes run > > Total time: 0.196 [sec] > [ perf record: Woken up 1 times to write data ] > [ perf record: Captured and wrote 0.178 MB perf.data (851 samples) ] > > > $ sudo perf report --stat | grep -A1 offcpu > offcpu-time stats: > SAMPLE events: 851 > > The benchmark passes messages by read/write and it creates off-cpu > events. With 400 processes, we can see more than 800 events. > > The child process tracking is also enabled when -p option is given. > But -t option does NOT as it only cares about the specific threads. > It may be different what perf_event does now, but I think it makes > more sense. > > You can get it from 'perf/offcpu-child-v2' branch in my tree > > https://git.kernel.org/pub/scm/linux/kernel/git/namhyung/linux-perf.git > > Thanks, > Namhyung > > > Namhyung Kim (4): > perf offcpu: Check process id for the given workload > perf offcpu: Parse process id separately > perf offcpu: Track child processes > perf offcpu: Update offcpu test for child process > > tools/perf/tests/shell/record_offcpu.sh | 57 ++++++++++++++++++++++--- > tools/perf/util/bpf_off_cpu.c | 53 ++++++++++++++++++++++- > tools/perf/util/bpf_skel/off_cpu.bpf.c | 38 ++++++++++++++++- > 3 files changed, 138 insertions(+), 10 deletions(-) > > > base-commit: b39c9e1b101d2992de9981673919ae55a088792c > -- > 2.37.1.595.g718a3a8f04-goog
Hello, This patch series implements inheritance of offcpu events for the child processes. Unlike perf events, BPF cannot know which task it should track except for ones set in a BPF map at the beginning. Add another BPF program to the fork path and add the process id to the map if the parent is tracked. Changes in v2) * drop already merged fixes * fix the shell test to omit noises With this change, it can get the correct off-cpu events for child processes. I've tested it with perf bench sched messaging which creates a lot of processes. $ sudo perf record -e dummy --off-cpu -- perf bench sched messaging # Running 'sched/messaging' benchmark: # 20 sender and receiver processes per group # 10 groups == 400 processes run Total time: 0.196 [sec] [ perf record: Woken up 1 times to write data ] [ perf record: Captured and wrote 0.178 MB perf.data (851 samples) ] $ sudo perf report --stat | grep -A1 offcpu offcpu-time stats: SAMPLE events: 851 The benchmark passes messages by read/write and it creates off-cpu events. With 400 processes, we can see more than 800 events. The child process tracking is also enabled when -p option is given. But -t option does NOT as it only cares about the specific threads. It may be different what perf_event does now, but I think it makes more sense. You can get it from 'perf/offcpu-child-v2' branch in my tree https://git.kernel.org/pub/scm/linux/kernel/git/namhyung/linux-perf.git Thanks, Namhyung Namhyung Kim (4): perf offcpu: Check process id for the given workload perf offcpu: Parse process id separately perf offcpu: Track child processes perf offcpu: Update offcpu test for child process tools/perf/tests/shell/record_offcpu.sh | 57 ++++++++++++++++++++++--- tools/perf/util/bpf_off_cpu.c | 53 ++++++++++++++++++++++- tools/perf/util/bpf_skel/off_cpu.bpf.c | 38 ++++++++++++++++- 3 files changed, 138 insertions(+), 10 deletions(-) base-commit: b39c9e1b101d2992de9981673919ae55a088792c