linux-kernel - Re: [PATCH v2 3/7] perf tools: Store clock references for -k/--clockid option

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Message-ID: <20200806124204.GE71359@kernel.org>
Date:   Thu, 6 Aug 2020 09:42:05 -0300
From:   Arnaldo Carvalho de Melo <acme@...nel.org>
To:     Jiri Olsa <jolsa@...nel.org>
Cc:     David Ahern <dsahern@...il.com>,
        lkml <linux-kernel@...r.kernel.org>,
        Ingo Molnar <mingo@...nel.org>,
        Namhyung Kim <namhyung@...nel.org>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Peter Zijlstra <a.p.zijlstra@...llo.nl>,
        Michael Petlan <mpetlan@...hat.com>,
        Ian Rogers <irogers@...gle.com>,
        Andi Kleen <ak@...ux.intel.com>,
        Geneviève Bastien <gbastien@...satic.net>,
        Wang Nan <wangnan0@...wei.com>,
        Jeremie Galarneau <jgalar@...icios.com>
Subject: Re: [PATCH v2 3/7] perf tools: Store clock references for
 -k/--clockid option

Em Wed, Aug 05, 2020 at 11:34:40AM +0200, Jiri Olsa escreveu:
> Adding new CLOCK_DATA feature that stores reference times
> when -k/--clockid option is specified.
> 
> It contains clock id and its reference time together with
> wall clock time taken at the 'same time', both values are
> in nanoseconds.
> 
> The format of data is as below:
> 
>   struct {
>        u32 version;  /* version = 1 */
>        u32 clockid;
>        u64 wall_clock_ns;
>        u64 clockid_time_ns;
>   };
> 
> This clock reference times will be used in following changes
> to display wall clock for perf events.
> 
> It's available only for recording with clockid specified,
> because it's the only case where we can get reference time
> to wallclock time. It's can't do that with perf clock yet.

Thanks, applied and added this committer testing section:


    Committer testing:

      $ perf record -h -k

       Usage: perf record [<options>] [<command>]
          or: perf record [<options>] -- <command> [<options>]

          -k, --clockid <clockid>
                                clockid to use for events, see clock_gettime()

      $ perf record -k monotonic sleep 1
      [ perf record: Woken up 1 times to write data ]
      [ perf record: Captured and wrote 0.017 MB perf.data (8 samples) ]
      $ perf report --header-only | grep clockid -A1
      # event : name = cycles:u, , id = { 88815, 88816, 88817, 88818, 88819, 88820, 88821, 88822 }, size = 120, { sample_period, sample_freq } = 4000, sample_type = IP|TID|TIME|PERIOD, read_format = ID, disabled = 1, inherit = 1, exclude_kernel = 1, mmap = 1, comm = 1, freq = 1, enable_on_exec = 1, task = 1, precise_ip = 3, sample_id_all = 1, exclude_guest = 1, mmap2 = 1, comm_exec = 1, use_clockid = 1, ksymbol = 1, bpf_event = 1, clockid = 1
      # CPU_TOPOLOGY info available, use -I to display
      --
      # clockid frequency: 1000 MHz
      # cpu pmu capabilities: branches=32, max_precise=3, pmu_name=skylake
      # clockid: monotonic (1)
      # reference time: 2020-08-06 09:40:21.619290 = 1596717621.619290 (TOD) = 21931.077673635 (monotonic)
      $