lkml.org 
[lkml]   [2016]   [Nov]   [29]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH] perf sched timehist: Improve error message when analyzing wrong file
Date
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

Add a helper to determine if a session has a specific event name,
and then use that helper for timehist. For perf sched timehist the
analysis requires at least sched_switch event, so check for it.

Now when analyzing a file without sched tracepoints you get:
root@f21-vbox:/tmp$ perf sched timehist
sched_switch event does not exist in file; nothing to analyze

Signed-off-by: David Ahern <dsahern@gmail.com>
---
tools/perf/builtin-sched.c | 5 ++++-
tools/perf/util/session.c | 12 ++++++++++++
tools/perf/util/session.h | 2 ++
3 files changed, 18 insertions(+), 1 deletion(-)

diff --git a/tools/perf/builtin-sched.c b/tools/perf/builtin-sched.c
index 870d94cd20ba..7c3c8176f51f 100644
--- a/tools/perf/builtin-sched.c
+++ b/tools/perf/builtin-sched.c
@@ -2629,8 +2629,11 @@ 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_session__has_event(session, "sched:sched_switch")) {
+ pr_err("sched_switch event does not exist in file; nothing to analyze\n");
goto out;
+ }

if (sched->show_migrations &&
perf_session__set_tracepoints_handlers(session, migrate_handlers))
diff --git a/tools/perf/util/session.c b/tools/perf/util/session.c
index f268201048a0..9bb3e03dcd8e 100644
--- a/tools/perf/util/session.c
+++ b/tools/perf/util/session.c
@@ -1897,6 +1897,18 @@ bool perf_session__has_traces(struct perf_session *session, const char *msg)
return false;
}

+bool perf_session__has_event(struct perf_session *session, const char *name)
+{
+ struct perf_evsel *evsel;
+
+ evlist__for_each_entry(session->evlist, evsel) {
+ if (!strcmp(perf_evsel__name(evsel), name))
+ return true;
+ }
+
+ return false;
+}
+
int maps__set_kallsyms_ref_reloc_sym(struct map **maps,
const char *symbol_name, u64 addr)
{
diff --git a/tools/perf/util/session.h b/tools/perf/util/session.h
index 4bd758553450..8609eca38c7f 100644
--- a/tools/perf/util/session.h
+++ b/tools/perf/util/session.h
@@ -64,6 +64,8 @@ int perf_session__resolve_callchain(struct perf_session *session,

bool perf_session__has_traces(struct perf_session *session, const char *msg);

+bool perf_session__has_event(struct perf_session *session, const char *name);
+
void perf_event__attr_swap(struct perf_event_attr *attr);

int perf_session__create_kernel_maps(struct perf_session *session);
--
2.7.4 (Apple Git-66)
\
 
 \ /
  Last update: 2016-11-29 20:59    [W:0.041 / U:0.752 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site