From: Andi Kleen <ak@linux.intel.com>
To: weilin.wang@intel.com
Cc: Namhyung Kim <namhyung@kernel.org>,
Ian Rogers <irogers@google.com>,
Arnaldo Carvalho de Melo <acme@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Ingo Molnar <mingo@redhat.com>,
Alexander Shishkin <alexander.shishkin@linux.intel.com>,
Jiri Olsa <jolsa@kernel.org>,
Adrian Hunter <adrian.hunter@intel.com>,
Kan Liang <kan.liang@linux.intel.com>,
linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org,
Perry Taylor <perry.taylor@intel.com>,
Samantha Alt <samantha.alt@intel.com>,
Caleb Biggers <caleb.biggers@intel.com>
Subject: Re: [RFC PATCH v4 2/6] perf stat: Fork and launch perf record when perf stat needs to get retire latency value for a metric.
Date: Tue, 12 Mar 2024 17:03:19 -0700 [thread overview]
Message-ID: <87le6nm20o.fsf@linux.intel.com> (raw)
In-Reply-To: <20240312234921.812685-3-weilin.wang@intel.com> (weilin wang's message of "Tue, 12 Mar 2024 19:49:17 -0400")
weilin.wang@intel.com writes:
> From: Weilin Wang <weilin.wang@intel.com>
>
> When retire_latency value is used in a metric formula, perf stat would fork a
> perf record process with "-e" and "-W" options. Perf record will collect
> required retire_latency values in parallel while perf stat is collecting
> counting values.
How does that work when the workload is specified on the command line?
The workload would run twice? That is very inefficient and may not
work if it's a large workload.
The perf tool infrastructure is imho not up to the task of such
parallel collection.
Also it won't work for very long collections because you will get a
very large perf.data. Better to use a pipeline.
I think it would be better if you made it a separate operation that can
generate a file that is then consumed by perf stat. This is also more efficient
because often the calibration is only needed once. And it's all under
user control so no nasty surprises.
-Andi
next prev parent reply other threads:[~2024-03-13 0:03 UTC|newest]
Thread overview: 19+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-03-12 23:49 [RFC PATCH v4 0/6] TPEBS counting mode support weilin.wang
2024-03-12 23:49 ` [RFC PATCH v4 1/6] perf stat: Parse and find tpebs events when parsing metrics to prepare for perf record sampling weilin.wang
2024-03-12 23:58 ` Andi Kleen
2024-03-13 0:27 ` Wang, Weilin
2024-03-12 23:49 ` [RFC PATCH v4 2/6] perf stat: Fork and launch perf record when perf stat needs to get retire latency value for a metric weilin.wang
2024-03-13 0:03 ` Andi Kleen [this message]
2024-03-13 0:26 ` Wang, Weilin
2024-03-13 0:56 ` Andi Kleen
2024-03-13 15:31 ` Wang, Weilin
2024-03-13 15:55 ` Andi Kleen
2024-03-13 16:23 ` Wang, Weilin
2024-03-14 0:00 ` Andi Kleen
2024-03-24 3:39 ` Ian Rogers
2024-03-12 23:49 ` [RFC PATCH v4 3/6] perf stat: Add retire latency values into the expr_parse_ctx to prepare for final metric calculation weilin.wang
2024-03-24 3:45 ` Ian Rogers
2024-03-12 23:49 ` [RFC PATCH v4 4/6] perf stat: Create another thread for sample data processing weilin.wang
2024-03-12 23:49 ` [RFC PATCH v4 5/6] perf stat: Add retire latency print functions to print out at the very end of print out weilin.wang
2024-03-12 23:49 ` [RFC PATCH v4 6/6] perf vendor events intel: Add MTL metric json files weilin.wang
2024-03-24 4:01 ` [RFC PATCH v4 0/6] TPEBS counting mode support Ian Rogers
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