| Message ID | 20220624231313.367909-1-namhyung@kernel.org (mailing list archive) |
|---|---|
| Headers | show |
| Series | perf tools: A couple of fixes for perf record --off-cpu (v1) | expand |
Em Fri, Jun 24, 2022 at 04:13:07PM -0700, Namhyung Kim escreveu: > Hello, > > The first patch fixes a build error on old kernels which has > task_struct->state field that is renamed to __state. Actually I made > a mistake when I wrote the code and assumed new kernel version. > > The second patch is to prevent invalid sample synthesize by > disallowing unsupported sample types. So I'll pick the first two for perf/urgent and then when that is merged into perf/core pick the rest, ok? - Arnaldo > The rest of the 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. > > 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-v1' branch in my tree > > https://git.kernel.org/pub/scm/linux/kernel/git/namhyung/linux-perf.git > > Thanks, > Namhyung > > > Namhyung Kim (6): > perf offcpu: Fix a build failure on old kernels > perf offcpu: Accept allowed sample types only > 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 | 60 +++++++++++++++++++++++-- > tools/perf/util/bpf_skel/off_cpu.bpf.c | 58 +++++++++++++++++++++--- > tools/perf/util/evsel.c | 9 ++++ > tools/perf/util/off_cpu.h | 9 ++++ > 5 files changed, 176 insertions(+), 17 deletions(-) > > > base-commit: 9886142c7a2226439c1e3f7d9b69f9c7094c3ef6 > -- > 2.37.0.rc0.161.g10f37bed90-goog
Hi Arnaldo, On Tue, Jun 28, 2022 at 7:40 AM Arnaldo Carvalho de Melo <acme@kernel.org> wrote: > > Em Fri, Jun 24, 2022 at 04:13:07PM -0700, Namhyung Kim escreveu: > > Hello, > > > > The first patch fixes a build error on old kernels which has > > task_struct->state field that is renamed to __state. Actually I made > > a mistake when I wrote the code and assumed new kernel version. > > > > The second patch is to prevent invalid sample synthesize by > > disallowing unsupported sample types. > > So I'll pick the first two for perf/urgent and then when that is merged > into perf/core pick the rest, ok? Sounds good! Thanks, Namhyung
Hello, The first patch fixes a build error on old kernels which has task_struct->state field that is renamed to __state. Actually I made a mistake when I wrote the code and assumed new kernel version. The second patch is to prevent invalid sample synthesize by disallowing unsupported sample types. The rest of the 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. 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-v1' branch in my tree https://git.kernel.org/pub/scm/linux/kernel/git/namhyung/linux-perf.git Thanks, Namhyung Namhyung Kim (6): perf offcpu: Fix a build failure on old kernels perf offcpu: Accept allowed sample types only 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 | 60 +++++++++++++++++++++++-- tools/perf/util/bpf_skel/off_cpu.bpf.c | 58 +++++++++++++++++++++--- tools/perf/util/evsel.c | 9 ++++ tools/perf/util/off_cpu.h | 9 ++++ 5 files changed, 176 insertions(+), 17 deletions(-) base-commit: 9886142c7a2226439c1e3f7d9b69f9c7094c3ef6