Messages in this thread |  | | Date | Mon, 13 Dec 2021 15:24:10 -0300 | From | Arnaldo Carvalho de Melo <> | Subject | Re: [RFC/PATCHSET 0/5] perf ftrace: Implement function latency histogram (v1) |
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Em Mon, Nov 29, 2021 at 03:18:25PM -0800, Namhyung Kim escreveu: > Hello, > > I've implemented 'latency' subcommand in the perf ftrace command to > show a histogram of function latency.
This still applies cleanly, I'll test it later.
- Arnaldo
> To handle new subcommands, the existing functionality is moved to > 'trace' subcommand while preserving backward compatibility of not > having a subcommand at all (defaults to 'trace'). > > The latency subcommand accepts a target (kernel, for now) function > with -T option and shows a histogram like below: > > $ sudo ./perf ftrace latency -a -T mutex_lock sleep 1 > # DURATION | COUNT | GRAPH | > 0 - 1 us | 2686 | ###################### | > 1 - 2 us | 976 | ######## | > 2 - 4 us | 879 | ####### | > 4 - 8 us | 481 | #### | > 8 - 16 us | 445 | ### | > 16 - 32 us | 1 | | > 32 - 64 us | 0 | | > 64 - 128 us | 0 | | > 128 - 256 us | 0 | | > 256 - 512 us | 0 | | > 512 - 1024 us | 0 | | > 1 - 2 ms | 0 | | > 2 - 4 ms | 0 | | > 4 - 8 ms | 0 | | > 8 - 16 ms | 0 | | > 16 - 32 ms | 0 | | > 32 - 64 ms | 0 | | > 64 - 128 ms | 0 | | > 128 - 256 ms | 0 | | > 256 - 512 ms | 0 | | > 512 - 1024 ms | 0 | | > 1 - ... s | 0 | | > > It basically use the function graph tracer to extract the duration of > the function. But with -b/--use-bpf option, it can use BPF to save > the histogram in the kernel. For the same function, it gets: > > $ sudo ./perf ftrace latency -a -b -T mutex_lock sleep 1 > # DURATION | COUNT | GRAPH | > 0 - 1 us | 4682 | ############################################# | > 1 - 2 us | 11 | | > 2 - 4 us | 0 | | > 4 - 8 us | 0 | | > 8 - 16 us | 7 | | > 16 - 32 us | 6 | | > 32 - 64 us | 0 | | > 64 - 128 us | 0 | | > 128 - 256 us | 0 | | > 256 - 512 us | 0 | | > 512 - 1024 us | 0 | | > 1 - 2 ms | 0 | | > 2 - 4 ms | 0 | | > 4 - 8 ms | 0 | | > 8 - 16 ms | 0 | | > 16 - 32 ms | 0 | | > 32 - 64 ms | 0 | | > 64 - 128 ms | 0 | | > 128 - 256 ms | 0 | | > 256 - 512 ms | 0 | | > 512 - 1024 ms | 0 | | > 1 - ... s | 0 | | > > > You can get the patches at 'perf/ftrace-latency-v1' branch on > > https://git.kernel.org/pub/scm/linux/kernel/git/namhyung/linux-perf.git > > > Thanks, > Namhyung > > > Namhyung Kim (5): > perf ftrace: Add 'trace' subcommand > perf ftrace: Move out common code from __cmd_ftrace > perf ftrace: Add 'latency' subcommand > perf ftrace: Add -b/--use-bpf option for latency subcommand > perf ftrace: Implement cpu and task filters in BPF > > tools/perf/Makefile.perf | 2 +- > tools/perf/builtin-ftrace.c | 443 +++++++++++++++++--- > tools/perf/util/Build | 1 + > tools/perf/util/bpf_ftrace.c | 154 +++++++ > tools/perf/util/bpf_skel/func_latency.bpf.c | 113 +++++ > tools/perf/util/ftrace.h | 81 ++++ > 6 files changed, 724 insertions(+), 70 deletions(-) > create mode 100644 tools/perf/util/bpf_ftrace.c > create mode 100644 tools/perf/util/bpf_skel/func_latency.bpf.c > create mode 100644 tools/perf/util/ftrace.h > > > base-commit: 8ab774587903771821b59471cc723bba6d893942 > -- > 2.34.0.rc2.393.gf8c9666880-goog
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- Arnaldo
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