From: Namhyung Kim namhyung@kernel.org
[ Upstream commit c0ee1d5ae8c8650031badcfca6483a28c0f94f38 ]
Currently perf stat shows some metrics (like IPC) for defined events. But when no aggregation mode is used (-A option), it shows incorrect values since it used a value from a different cpu.
Before:
$ perf stat -aA -e cycles,instructions sleep 1
Performance counter stats for 'system wide':
CPU0 116,057,380 cycles CPU1 86,084,722 cycles CPU2 99,423,125 cycles CPU3 98,272,994 cycles CPU0 53,369,217 instructions # 0.46 insn per cycle CPU1 33,378,058 instructions # 0.29 insn per cycle CPU2 58,150,086 instructions # 0.50 insn per cycle CPU3 40,029,703 instructions # 0.34 insn per cycle
1.001816971 seconds time elapsed
So the IPC for CPU1 should be 0.38 (= 33,378,058 / 86,084,722) but it was 0.29 (= 33,378,058 / 116,057,380) and so on.
After:
$ perf stat -aA -e cycles,instructions sleep 1
Performance counter stats for 'system wide':
CPU0 109,621,384 cycles CPU1 159,026,454 cycles CPU2 99,460,366 cycles CPU3 124,144,142 cycles CPU0 44,396,706 instructions # 0.41 insn per cycle CPU1 120,195,425 instructions # 0.76 insn per cycle CPU2 44,763,978 instructions # 0.45 insn per cycle CPU3 69,049,079 instructions # 0.56 insn per cycle
1.001910444 seconds time elapsed
Fixes: 44d49a600259 ("perf stat: Support metrics in --per-core/socket mode") Reported-by: Sam Xi xyzsam@google.com Signed-off-by: Namhyung Kim namhyung@kernel.org Reviewed-by: Andi Kleen ak@linux.intel.com Acked-by: Jiri Olsa jolsa@redhat.com Cc: Alexander Shishkin alexander.shishkin@linux.intel.com Cc: Ian Rogers irogers@google.com Cc: Mark Rutland mark.rutland@arm.com Cc: Peter Zijlstra peterz@infradead.org Cc: Stephane Eranian eranian@google.com Link: http://lore.kernel.org/lkml/20201127041404.390276-1-namhyung@kernel.org Signed-off-by: Arnaldo Carvalho de Melo acme@redhat.com Signed-off-by: Sasha Levin sashal@kernel.org --- tools/perf/util/stat-display.c | 5 +---- 1 file changed, 1 insertion(+), 4 deletions(-)
diff --git a/tools/perf/util/stat-display.c b/tools/perf/util/stat-display.c index 493ec372fdec4..f2709879bad96 100644 --- a/tools/perf/util/stat-display.c +++ b/tools/perf/util/stat-display.c @@ -324,13 +324,10 @@ static int first_shadow_cpu(struct perf_stat_config *config, struct evlist *evlist = evsel->evlist; int i;
- if (!config->aggr_get_id) - return 0; - if (config->aggr_mode == AGGR_NONE) return id;
- if (config->aggr_mode == AGGR_GLOBAL) + if (!config->aggr_get_id) return 0;
for (i = 0; i < evsel__nr_cpus(evsel); i++) {