From: Namhyung Kim <namhyung@kernel.org>
To: Arnaldo Carvalho de Melo <acme@kernel.org>, Jiri Olsa <jolsa@redhat.com>
Cc: Ingo Molnar <mingo@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Mark Rutland <mark.rutland@arm.com>,
Alexander Shishkin <alexander.shishkin@linux.intel.com>,
LKML <linux-kernel@vger.kernel.org>,
Stephane Eranian <eranian@google.com>,
Ian Rogers <irogers@google.com>, Sam Xi <xyzsam@google.com>,
Andi Kleen <ak@linux.intel.com>
Subject: [PATCH v2 1/2] perf stat: Use proper cpu for shadow stats
Date: Fri, 27 Nov 2020 13:14:03 +0900 [thread overview]
Message-ID: <20201127041404.390276-1-namhyung@kernel.org> (raw)
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
Reported-by: Sam Xi <xyzsam@google.com>
Fixes: 44d49a600259 ("perf stat: Support metrics in --per-core/socket mode")
Reviewed-by: Andi Kleen <ak@linux.intel.com>
Acked-by: Jiri Olsa <jolsa@redhat.com>
Signed-off-by: Namhyung Kim <namhyung@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 4b57c0c07632..a963b5b8eb72 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++) {
--
2.29.2.454.gaff20da3a2-goog
next reply other threads:[~2020-11-27 4:14 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2020-11-27 4:14 Namhyung Kim [this message]
2020-11-27 4:14 ` [PATCH v2 2/2] perf test: Add shadow stat test Namhyung Kim
2020-11-30 11:59 ` Arnaldo Carvalho de Melo
2020-11-27 17:32 ` [PATCH v2 1/2] perf stat: Use proper cpu for shadow stats Arnaldo Carvalho de Melo
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to=20201127041404.390276-1-namhyung@kernel.org \
--to=namhyung@kernel.org \
--cc=acme@kernel.org \
--cc=ak@linux.intel.com \
--cc=alexander.shishkin@linux.intel.com \
--cc=eranian@google.com \
--cc=irogers@google.com \
--cc=jolsa@redhat.com \
--cc=linux-kernel@vger.kernel.org \
--cc=mark.rutland@arm.com \
--cc=mingo@kernel.org \
--cc=peterz@infradead.org \
--cc=xyzsam@google.com \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).