From: Andi Kleen <ak@linux.intel.com>
To: "Wang, Weilin" <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>,
"Hunter, Adrian" <adrian.hunter@intel.com>,
Kan Liang <kan.liang@linux.intel.com>,
"linux-perf-users@vger.kernel.org"
<linux-perf-users@vger.kernel.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
"Taylor, Perry" <perry.taylor@intel.com>,
"Alt, Samantha" <samantha.alt@intel.com>,
"Biggers, Caleb" <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: Wed, 13 Mar 2024 17:00:38 -0700 [thread overview]
Message-ID: <ZfI-JqTZevIhEa3o@tassilo> (raw)
In-Reply-To: <CO6PR11MB5635D2EAC53C2CD2B36D4BF5EE2A2@CO6PR11MB5635.namprd11.prod.outlook.com>
> We could use -a -C and cgroup together. I think this could be a useful use case.
> There could be other improvement to the implementation in next step. But I believe
I don't know how you would improve it. A lot of the problems are fairly
fundamental.
> current implementation could provide users the access to our new feature with
> accurate results
> and without adding too much overhead.
perf record increases the overhead a lot over a perf stat! Sampling
is much more expensive than counting.
That should be at least a order of magnitude difference.
Another advantage of doing it separately.
That will also make it inaccurate.
Please do a proper implementation. This one is no good.
You can likely reuse a lot of your code:
- Add a perf calibrate to run the profile step separately that generates the JSON
- Add a --metrics option to perf to read the resulting JSON
- Add some mechanism to read a default JSON as fallback. I guess this
one could be compiled in to avoid a dependency on an installed file.
-Andi
next prev parent reply other threads:[~2024-03-14 0:00 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
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 [this message]
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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