perf top: Display slow reader warning when droping samples

tip:perf/core tip-bot for Jiri Olsa 1 participant 1 message Dec 14, 2018 perf events

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2018-12-14 20:52 UTC #0 lore raw

Commit-ID:  ffec48b734491d7c687c5cb430bffdbb9c56824e
Gitweb:     https://git.kernel.org/tip/ffec48b734491d7c687c5cb430bffdbb9c56824e
Author:     Jiri Olsa <[email protected]>
AuthorDate: Mon, 19 Nov 2018 11:12:01 +0100
Committer:  Arnaldo Carvalho de Melo <[email protected]>
CommitDate: Thu, 6 Dec 2018 14:12:34 -0300

perf top: Display slow reader warning when droping samples

Currently we display the "Too slow to read ring buffer.." helpline only in the slow reader thread. This patch triggers it also when the processing thread drops samples, because it has the same reason, which is too many data on input.

Acked-by David S. Miller <[email protected]>

Acked-by Namhyung Kim <[email protected]>

Cc Alexander Shishkin <[email protected]>

Cc Peter Zijlstra <[email protected]>

Link https://lkml.kernel.org/n/[email protected] open here

Signed-off-by Jiri Olsa <[email protected]>

---
 tools/perf/builtin-top.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

tools/perf/builtin-top.c +1 -1

index 9166f6087e3f..f22c531be366 100644
@@ -571,7 +571,7 @@ static void perf_top__sort_new_samples(void *arg)
 	hists__collapse_resort(hists, NULL);
 	perf_evsel__output_resort(evsel, NULL);
 
-	if (t->lost)
+	if (t->lost || t->drop)
 		pr_warning("Too slow to read ring buffer (change period (-c/-F) or limit CPUs (-C)\n");
 
 	perf_top__reset_sample_counters(t);