On 11/30/16, David Ahern <dsah...@gmail.com> wrote:
> Arnaldo reported an unhelpful error message when running perf sched
> timehist on a file that did not contain sched tracepoints:
>
> [root@jouet ~]# perf sched timehist
> No trace sample to read. Did you call 'perf record -R'?
>
> [root@jouet ~]# perf evlist -v
> cycles:ppp: size: 112, { sample_period, sample_freq }: 4000,
> sample_type: IP|TID|TIME|CALLCHAIN|CPU|PERIOD, disabled: 1, inherit: 1,
> mmap: 1, comm: 1, freq: 1, task: 1, precise_ip: 3, sample_id_all: 1,
> exclude_guest: 1, mmap2: 1, comm_exec: 1
>
> Change the has_traces check to look for the sched_switch event. Analysis
> for perf sched timehist requires at least this event.
>
> Now when analyzing a file without sched tracepoints you get:
>
> root@f21-vbox:/tmp$ perf sched timehist
> No sched_switch events found. Have you run 'perf sched record'?
>
> Signed-off-by: David Ahern <dsah...@gmail.com>
Acked-by: Namhyung Kim <namhy...@kernel.org>
Thanks,
Namhyung
> ---
> tools/perf/builtin-sched.c | 6 +++++-
> 1 file changed, 5 insertions(+), 1 deletion(-)
>
> diff --git a/tools/perf/builtin-sched.c b/tools/perf/builtin-sched.c
> index 870d94cd20ba..84c39f177bef 100644
> --- a/tools/perf/builtin-sched.c
> +++ b/tools/perf/builtin-sched.c
> @@ -2629,8 +2629,12 @@ static int perf_sched__timehist(struct perf_sched
> *sched)
> if (perf_session__set_tracepoints_handlers(session, handlers))
> goto out;
>
> - if (!perf_session__has_traces(session, "record -R"))
> + /* sched_switch event at a minimum needs to exist */
> + if (!perf_evlist__find_tracepoint_by_name(session->evlist,
> + "sched:sched_switch")) {
> + pr_err("No sched_switch events found. Have you run 'perf sched
> record'?\n");
> goto out;
> + }
>
> if (sched->show_migrations &&
> perf_session__set_tracepoints_handlers(session, migrate_handlers))
> --
> 2.7.4 (Apple Git-66)
>
>
--
Thanks,
Namhyung Kim
