From d9aade7fd27a604bbffd363e6a68416ef51bab88 Mon Sep 17 00:00:00 2001 From: Arnaldo Carvalho de Melo Date: Thu, 18 Feb 2016 13:34:09 -0300 Subject: [PATCH] perf evlist: Handle -EINVAL for sample_freq > max_sample_rate in strerror_open() When running the "code reading" test we get: # perf test -v "code reading" 2>&1 | tail -5 Parsing event 'cycles:u' perf_evlist__open failed test child finished with -1 ---- end ---- Test object code reading: FAILED! # And with -vv we get the errno value, -22, i.e. -EINVAL, but we can do better and handle the case at hand, with this patch it becomes: # perf test -v "code reading" 2>&1 | tail -7 perf_evlist__open() failed! Error: Invalid argument. Hint: Check /proc/sys/kernel/perf_event_max_sample_rate. Hint: The current value is 1000 and 4000 is being requested. test child finished with -1 ---- end ---- Test object code reading: FAILED! # Next patch will make this 'perf test' entry to use perf_evlist__strerror() Cc: Adrian Hunter Cc: Jiri Olsa Cc: Namhyung Kim Cc: Steven Noonan Cc: Wang Nan Link: http://lkml.kernel.org/n/tip-i31ai6kfefn75eapejjokfhc@git.kernel.org Signed-off-by: Arnaldo Carvalho de Melo --- tools/perf/util/evlist.c | 20 +++++++++++++++++++- 1 file changed, 19 insertions(+), 1 deletion(-) diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c index a7eb0eae9938..0f577162c699 100644 --- a/tools/perf/util/evlist.c +++ b/tools/perf/util/evlist.c @@ -1624,7 +1624,7 @@ size_t perf_evlist__fprintf(struct perf_evlist *evlist, FILE *fp) return printed + fprintf(fp, "\n"); } -int perf_evlist__strerror_open(struct perf_evlist *evlist __maybe_unused, +int perf_evlist__strerror_open(struct perf_evlist *evlist, int err, char *buf, size_t size) { int printed, value; @@ -1652,7 +1652,25 @@ int perf_evlist__strerror_open(struct perf_evlist *evlist __maybe_unused, "Hint:\tTry: 'sudo sh -c \"echo -1 > /proc/sys/kernel/perf_event_paranoid\"'\n" "Hint:\tThe current value is %d.", value); break; + case EINVAL: { + struct perf_evsel *first = perf_evlist__first(evlist); + int max_freq; + + if (sysctl__read_int("kernel/perf_event_max_sample_rate", &max_freq) < 0) + goto out_default; + + if (first->attr.sample_freq < (u64)max_freq) + goto out_default; + + printed = scnprintf(buf, size, + "Error:\t%s.\n" + "Hint:\tCheck /proc/sys/kernel/perf_event_max_sample_rate.\n" + "Hint:\tThe current value is %d and %" PRIu64 " is being requested.", + emsg, max_freq, first->attr.sample_freq); + break; + } default: +out_default: scnprintf(buf, size, "%s", emsg); break; } -- 2.20.1