Commit-ID: 02d8dabc50f94353075f2f62b1047c1306e8bf92
Gitweb: http://git.kernel.org/tip/02d8dabc50f94353075f2f62b1047c1306e8bf92
Author: Stephane Eranian <eranian@xxxxxxxxxx>
AuthorDate: Thu, 3 Sep 2015 15:23:40 +0200
Committer: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
CommitDate: Wed, 16 Sep 2015 18:01:03 -0300
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@xxxxxxxxxx>
Cc: Adrian Hunter <adrian.hunter@xxxxxxxxx>
Cc: Andi Kleen <ak@xxxxxxxxxxxxxxx>
Cc: David Ahern <dsahern@xxxxxxxxx>
Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: Kan Liang <kan.liang@xxxxxxxxx>
Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Link: http://lkml.kernel.org/r/1441286620-10117-1-git-send-email-eranian@xxxxxxxxxx
Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
---
tools/perf/util/stat.c | 16 ++++++++++++++--
1 file changed, 14 insertions(+), 2 deletions(-)
diff --git a/tools/perf/util/stat.c b/tools/perf/util/stat.c
index 415c359..2d065d0 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;
}
--
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