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authorStephane Eranian <eranian@google.com>2015-09-03 15:23:40 +0200
committerArnaldo Carvalho de Melo <acme@redhat.com>2015-09-16 18:01:03 -0300
commit02d8dabc50f94353075f2f62b1047c1306e8bf92 (patch)
tree32a17c8f2428f4dccb5b66caaf07fa122c8a556c /tools/perf
parentf6cf87f748ff9480f97ff9c5caf6d6faacf52aa1 (diff)
perf stat: Fix per-pkg event reporting bug
Per-pkg events need to be captured once per processor socket. The code in check_per_pkg() ensures only one value per processor package is used. However there is a problem with this function in case the first CPU of the package does not measure anything for the per-pkg event, but other CPUs do. Consider the following: $ create cgroup FOO; echo $$ >FOO/tasks; taskset -c 1 noploop & $ perf stat -a -I 1000 -e intel_cqm/llc_occupancy/ -G FOO sleep 100 1.00000 <not counted> Bytes intel_cqm/llc_occupancy/ FOO The reason for this is that CPU0 in the cgroup has nothing running on it. Yet check_per_plg() will mark socket0 as processed and no other event value will be considered for the socket. This patch fixes the problem by having check_per_pkg() only consider events which actually ran. Signed-off-by: Stephane Eranian <eranian@google.com> Cc: Adrian Hunter <adrian.hunter@intel.com> Cc: Andi Kleen <ak@linux.intel.com> Cc: David Ahern <dsahern@gmail.com> Cc: Jiri Olsa <jolsa@redhat.com> Cc: Kan Liang <kan.liang@intel.com> Cc: Namhyung Kim <namhyung@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Link: http://lkml.kernel.org/r/1441286620-10117-1-git-send-email-eranian@google.com Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Diffstat (limited to 'tools/perf')
-rw-r--r--tools/perf/util/stat.c16
1 files changed, 14 insertions, 2 deletions
diff --git a/tools/perf/util/stat.c b/tools/perf/util/stat.c
index 415c359de465..2d065d065b67 100644
--- a/tools/perf/util/stat.c
+++ b/tools/perf/util/stat.c
@@ -196,7 +196,8 @@ static void zero_per_pkg(struct perf_evsel *counter)
memset(counter->per_pkg_mask, 0, MAX_NR_CPUS);
}
-static int check_per_pkg(struct perf_evsel *counter, int cpu, bool *skip)
+static int check_per_pkg(struct perf_evsel *counter,
+ struct perf_counts_values *vals, int cpu, bool *skip)
{
unsigned long *mask = counter->per_pkg_mask;
struct cpu_map *cpus = perf_evsel__cpus(counter);
@@ -218,6 +219,17 @@ static int check_per_pkg(struct perf_evsel *counter, int cpu, bool *skip)
counter->per_pkg_mask = mask;
}
+ /*
+ * we do not consider an event that has not run as a good
+ * instance to mark a package as used (skip=1). Otherwise
+ * we may run into a situation where the first CPU in a package
+ * is not running anything, yet the second is, and this function
+ * would mark the package as used after the first CPU and would
+ * not read the values from the second CPU.
+ */
+ if (!(vals->run && vals->ena))
+ return 0;
+
s = cpu_map__get_socket(cpus, cpu);
if (s < 0)
return -1;
@@ -235,7 +247,7 @@ process_counter_values(struct perf_stat_config *config, struct perf_evsel *evsel
static struct perf_counts_values zero;
bool skip = false;
- if (check_per_pkg(evsel, cpu, &skip)) {
+ if (check_per_pkg(evsel, count, cpu, &skip)) {
pr_err("failed to read per-pkg counter\n");
return -1;
}