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| author |   Stephane Eranian <eranian@google.com> | 2017-04-12 11:23:01 -0700 |
|---|---|---|
| committer |   Arnaldo Carvalho de Melo <acme@redhat.com> | 2017-04-13 10:40:36 -0300 |
| commit | db49a71798a38f3ddf3f3462703328dca39b1ac7 (patch) | |
| tree | c6c7ba37ba155f9e89314f65059f9c3f3a699fcf /tools/perf/util/evsel.c | |
| parent | perf tools: Pass PYTHON config to feature detection (diff) | |
| download | linux-dev-db49a71798a38f3ddf3f3462703328dca39b1ac7.tar.xz linux-dev-db49a71798a38f3ddf3f3462703328dca39b1ac7.zip | |
perf stat: Fix bug in handling events in error state
(This is a patch has been sitting in the Intel CQM/CMT driver series for
a while, despite not depend on it. Sending it now independently since
the series is being discarded.)
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 <eranian@google.com>
Reviewed-by: David Carrillo-Cisneros <davidcc@google.com>
Acked-by: Jiri Olsa <jolsa@redhat.com>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Mathieu Poirier <mathieu.poirier@linaro.org>
Cc: Paul Turner <pjt@google.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Wang Nan <wangnan0@huawei.com>
Link: http://lkml.kernel.org/r/20170412182301.44406-1-davidcc@google.com
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Diffstat (limited to 'tools/perf/util/evsel.c')
| -rw-r--r-- | tools/perf/util/evsel.c | 4 |
1 files changed, 2 insertions, 2 deletions
diff --git a/tools/perf/util/evsel.c b/tools/perf/util/evsel.c index 8f5d86bd3501..3779b9f3f134 100644 --- a/tools/perf/util/evsel.c +++ b/tools/perf/util/evsel.c @@ -1239,7 +1239,7 @@ 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; @@ -1257,7 +1257,7 @@ 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); |