From f45bf8d3939d8f32f06ec12e56d2b8651c5437b4 Mon Sep 17 00:00:00 2001 From: David Ahern Date: Tue, 29 Nov 2016 13:39:48 -0700 Subject: [PATCH] perf sched timehist: Improve error message when analyzing wrong file 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 Reported-and-Tested-by: Arnaldo Carvalho de Melo Acked-by: Namhyung Kim Cc: Jiri Olsa Cc: Peter Zijlstra Link: http://lkml.kernel.org/r/1480451988-43673-1-git-send-email-dsahern@gmail.com Signed-off-by: Arnaldo Carvalho de Melo --- 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)) -- 2.20.1