lkml.org 
[lkml]   [2020]   [Dec]   [1]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
Patch in this message
/
From
Subject[PATCH 5.9 139/152] perf stat: Use proper cpu for shadow stats
Date
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++) {
--
2.27.0


\
 
 \ /
  Last update: 2020-12-01 10:16    [W:0.325 / U:1.652 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site