From: Stephane Eranian <[email protected]> When an event is in error state, read() returns 0 instead of sizeof() buffer. In certain modes, such as interval printing, ignoring the 0 return value may cause bogus count deltas to be computed and thus invalid results printed.
this patch fixes this problem by modifying read_counters() to mark the event as not scaled (scaled = -1) to force the printout routine to show <NOT COUNTED>. Signed-off-by: Stephane Eranian <[email protected]> Signed-off-by: Vikas Shivappa <[email protected]> --- tools/perf/builtin-stat.c | 12 +++++++++--- tools/perf/util/evsel.c | 4 ++-- 2 files changed, 11 insertions(+), 5 deletions(-) diff --git a/tools/perf/builtin-stat.c b/tools/perf/builtin-stat.c index a02f2e9..9f109b9 100644 --- a/tools/perf/builtin-stat.c +++ b/tools/perf/builtin-stat.c @@ -310,8 +310,12 @@ static int read_counter(struct perf_evsel *counter) struct perf_counts_values *count; count = perf_counts(counter->counts, cpu, thread); - if (perf_evsel__read(counter, cpu, thread, count)) + if (perf_evsel__read(counter, cpu, thread, count)) { + counter->counts->scaled = -1; + perf_counts(counter->counts, cpu, thread)->ena = 0; + perf_counts(counter->counts, cpu, thread)->run = 0; return -1; + } if (STAT_RECORD) { if (perf_evsel__write_stat_event(counter, cpu, thread, count)) { @@ -336,12 +340,14 @@ static int read_counter(struct perf_evsel *counter) static void read_counters(void) { struct perf_evsel *counter; + int ret; evlist__for_each_entry(evsel_list, counter) { - if (read_counter(counter)) + ret = read_counter(counter); + if (ret) pr_debug("failed to read counter %s\n", counter->name); - if (perf_stat_process_counter(&stat_config, counter)) + if (ret == 0 && perf_stat_process_counter(&stat_config, counter)) pr_warning("failed to process counter %s\n", counter->name); } } diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c index 04e536a..7aa10e3 100644 --- a/tools/perf/util/evsel.c +++ b/tools/perf/util/evsel.c @@ -1232,7 +1232,7 @@ int perf_evsel__read(struct perf_evsel *evsel, int cpu, int thread, if (FD(evsel, cpu, thread) < 0) return -EINVAL; - if (readn(FD(evsel, cpu, thread), count, sizeof(*count)) < 0) + if (readn(FD(evsel, cpu, thread), count, sizeof(*count)) <= 0) return -errno; return 0; @@ -1250,7 +1250,7 @@ int __perf_evsel__read_on_cpu(struct perf_evsel *evsel, if (evsel->counts == NULL && perf_evsel__alloc_counts(evsel, cpu + 1, thread + 1) < 0) return -ENOMEM; - if (readn(FD(evsel, cpu, thread), &count, nv * sizeof(u64)) < 0) + if (readn(FD(evsel, cpu, thread), &count, nv * sizeof(u64)) <= 0) return -errno; perf_evsel__compute_deltas(evsel, cpu, thread, &count); -- 1.9.1
