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    SubjectRe: [PATCH 2/2] perf, tools: Add --delay support to perf record
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    Hi Andi,

    On Tue, 7 Jan 2014 14:14:07 -0800, Andi Kleen wrote:
    > From: Andi Kleen <ak@linux.intel.com>
    >
    > perf stat has a --delay option to delay measuring the workload.
    > This is useful to skip measuring the startup phase of the program, which
    > is often very different from the main workload.
    >
    > The same is useful for perf record when sampling. Add --delay to perf record too.
    > -D was already taken for record, so there is only a long option.
    >
    > Signed-off-by: Andi Kleen <ak@linux.intel.com>
    > ---
    > tools/perf/Documentation/perf-record.txt | 4 ++++
    > tools/perf/builtin-record.c | 9 ++++++++-
    > tools/perf/perf.h | 1 +
    > tools/perf/util/evsel.c | 5 +++--
    > 4 files changed, 16 insertions(+), 3 deletions(-)
    >
    > diff --git a/tools/perf/Documentation/perf-record.txt b/tools/perf/Documentation/perf-record.txt
    > index 43b42c4..e349151 100644
    > --- a/tools/perf/Documentation/perf-record.txt
    > +++ b/tools/perf/Documentation/perf-record.txt
    > @@ -207,6 +207,10 @@ Force the use of per-cpu mmaps. By default, when tasks are specified (i.e. -p,
    > forces per-cpu mmaps. A side-effect of that is that inheritance is
    > automatically enabled. Add the -i option also to disable inheritance.
    >
    > +--delay msecs::
    > +After starting the program, wait msecs before measuring. This is useful to
    > +filter out the startup phase of the program, which is often very different.
    > +
    > SEE ALSO
    > --------
    > linkperf:perf-stat[1], linkperf:perf-list[1]
    > diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c
    > index 7c8020a..110158e 100644
    > --- a/tools/perf/builtin-record.c
    > +++ b/tools/perf/builtin-record.c
    > @@ -506,7 +506,7 @@ static int __cmd_record(struct perf_record *rec, int argc, const char **argv)
    > * (apart from group members) have enable_on_exec=1 set,
    > * so don't spoil it by prematurely enabling them.
    > */
    > - if (!target__none(&opts->target))
    > + if (!target__none(&opts->target) && !opts->initial_delay)
    > perf_evlist__enable(evsel_list);
    >
    > /*
    > @@ -515,6 +515,11 @@ static int __cmd_record(struct perf_record *rec, int argc, const char **argv)
    > if (forks)
    > perf_evlist__start_workload(evsel_list);
    >
    > + if (opts->initial_delay) {
    > + usleep(opts->initial_delay * 1000);
    > + perf_evlist__enable(evsel_list);
    > + }
    > +
    > for (;;) {
    > int hits = rec->samples;
    >
    > @@ -890,6 +895,8 @@ const struct option record_options[] = {
    > "sample transaction flags (special events only)"),
    > OPT_BOOLEAN(0, "force-per-cpu", &record.opts.target.force_per_cpu,
    > "force the use of per-cpu mmaps"),
    > + OPT_UINTEGER(0, "delay", &record.opts.initial_delay,
    > + "ms to wait before starting measurement after program start"),
    > OPT_END()
    > };
    >
    > diff --git a/tools/perf/perf.h b/tools/perf/perf.h
    > index b079304..d052f1d 100644
    > --- a/tools/perf/perf.h
    > +++ b/tools/perf/perf.h
    > @@ -268,6 +268,7 @@ struct perf_record_opts {
    > u64 user_interval;
    > u16 stack_dump_size;
    > bool sample_transaction;
    > + unsigned initial_delay;
    > };
    >
    > #endif
    > diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c
    > index 46dd4c2..4a70656 100644
    > --- a/tools/perf/util/evsel.c
    > +++ b/tools/perf/util/evsel.c
    > @@ -689,14 +689,15 @@ void perf_evsel__config(struct perf_evsel *evsel,
    > * Disabling only independent events or group leaders,
    > * keeping group members enabled.
    > */
    > - if (perf_evsel__is_group_leader(evsel))
    > + if (perf_evsel__is_group_leader(evsel) || opts->initial_delay)
    > attr->disabled = 1;

    It seems this hunk is not needed since it'll disable group member events
    which is not what we want. Note that the perf_evlist__enable/disable()
    only work for the leaders.

    Thanks,
    Namhyung

    >
    > /*
    > * Setting enable_on_exec for independent events and
    > * group leaders for traced executed by perf.
    > */
    > - if (target__none(&opts->target) && perf_evsel__is_group_leader(evsel))
    > + if (target__none(&opts->target) && perf_evsel__is_group_leader(evsel) &&
    > + !opts->initial_delay)
    > attr->enable_on_exec = 1;
    > }


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