Re: [PATCHv2] perf/stat: Report unsupported events properly

From: David Ahern
Date: Fri Feb 13 2015 - 14:39:31 EST




On 02/13/2015 11:40 AM, Suzuki K. Poulose wrote:
From: "Suzuki K. Poulose" <suzuki.poulose@xxxxxxx>

Commit 1971f59 (perf stat: Use read_counter in read_counter_aggr )
broke the perf stat output for unsupported counters.

$ perf stat -v -a -C 0 -e CCI_400/config=24/ sleep 1
Warning:
CCI_400/config=24/ event is not supported by the kernel.

Performance counter stats for 'system wide':

0 CCI_400/config=24/

1.080265400 seconds time elapsed

Where it used to be :

$ perf stat -v -a -C 0 -e CCI_400/config=24/ sleep 1
Warning:
CCI_400/config=24/ event is not supported by the kernel.

Performance counter stats for 'system wide':

<not supported> CCI_400/config=24/

1.083840675 seconds time elapsed

This patch fixes the issues by checking if the counter is supported,
before reading and logging the counter value.

Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
Signed-off-by: Suzuki K. Poulose <suzuki.poulose@xxxxxxx>
---
tools/perf/builtin-stat.c | 5 ++++-
1 file changed, 4 insertions(+), 1 deletion(-)

diff --git a/tools/perf/builtin-stat.c b/tools/perf/builtin-stat.c
index e598e4e..d28949d 100644
--- a/tools/perf/builtin-stat.c
+++ b/tools/perf/builtin-stat.c
@@ -510,6 +510,9 @@ static int read_counter(struct perf_evsel *counter)
int ncpus = perf_evsel__nr_cpus(counter);
int cpu, thread;

+ if (!counter->supported)
+ return -ENOENT;
+
if (counter->system_wide)
nthreads = 1;

@@ -1285,7 +1288,7 @@ static void print_counter_aggr(struct perf_evsel *counter, char *prefix)
if (prefix)
fprintf(output, "%s", prefix);

- if (scaled == -1) {
+ if (scaled == -1 || !counter->supported) {
fprintf(output, "%*s%s",
csv_output ? 0 : 18,
counter->supported ? CNTR_NOT_COUNTED : CNTR_NOT_SUPPORTED,


Just hit this as well.

Acked-and-Tested-by: David Ahern <dsahern@xxxxxxxxx>

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