From: Ian Rogers <irogers@google.com>
To: Howard Chu <howardchu95@gmail.com>
Cc: acme@kernel.org, namhyung@kernel.org, jolsa@kernel.org,
adrian.hunter@intel.com, linux-perf-users@vger.kernel.org,
linux-kernel@vger.kernel.org,
Alexander Shishkin <alexander.shishkin@linux.intel.com>,
Ingo Molnar <mingo@redhat.com>,
James Clark <james.clark@linaro.org>,
Kan Liang <kan.liang@linux.intel.com>,
Mark Rutland <mark.rutland@arm.com>,
Peter Zijlstra <peterz@infradead.org>,
Arnaldo Carvalho de Melo <acme@redhat.com>
Subject: Re: [PATCH v15 10/10] perf test: Add direct off-cpu test
Date: Tue, 18 Feb 2025 11:32:33 -0800 [thread overview]
Message-ID: <CAP-5=fXae_851WezB5rNkv6cp2DfAWobJ-cbehKy3eiFe8F9Ow@mail.gmail.com> (raw)
In-Reply-To: <CAH0uvohY6fBaJvMZNi-fcHEW1Dw7Zp5Q_+ZxNgcaaFary-3sWw@mail.gmail.com>
On Thu, Feb 13, 2025 at 3:04 PM Howard Chu <howardchu95@gmail.com> wrote:
>
> Hello,
>
> On Thu, Feb 13, 2025 at 3:00 PM Howard Chu <howardchu95@gmail.com> wrote:
> >
> > Why is there a --off-cpu-thresh 2000?
> >
> > We collect an off-cpu period __ONLY ONCE__, either in direct sample form,
> > or in accumulated form (in BPF stack trace map).
> >
> > If I don't add --off-cpu-thresh 2000, the sample in the original test
> > goes into the ring buffer instead of the BPF stack trace map.
> >
> > Additionally, when using -e dummy, the ring buffer is not open, causing
> > us to lose a sample.
>
> Just noticed that this commit message is wrong, should be:
> """
> Add tests for direct off-cpu samples and --off-cpu-thresh option.
> """
Tested-by: Ian Rogers <irogers@google.com>
```
121: perf record offcpu profiling tests : Ok
```
I'd be tempted to keep the comments about why 2000 next to the actual
code rather than in the commit message. In the code the value is 12000
and not 2000 though?
Thanks,
Ian
next prev parent reply other threads:[~2025-02-18 19:32 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-02-13 22:59 [PATCH v15 00/10] perf record --off-cpu: Dump off-cpu samples directly Howard Chu
2025-02-13 23:00 ` [PATCH v15 01/10] perf evsel: Expose evsel__is_offcpu_event() for future use Howard Chu
2025-02-13 23:00 ` [PATCH v15 02/10] perf record --off-cpu: Parse off-cpu event Howard Chu
2025-02-13 23:00 ` [PATCH v15 03/10] perf record --off-cpu: Preparation of off-cpu BPF program Howard Chu
2025-02-13 23:00 ` [PATCH v15 04/10] perf record --off-cpu: Dump off-cpu samples in BPF Howard Chu
2025-02-13 23:00 ` [PATCH v15 05/10] perf evsel: Assemble offcpu samples Howard Chu
2025-02-13 23:00 ` [PATCH v15 06/10] perf record --off-cpu: Disable perf_event's callchain collection Howard Chu
2025-02-13 23:00 ` [PATCH v15 07/10] perf script: Display off-cpu samples correctly Howard Chu
2025-02-13 23:00 ` [PATCH v15 08/10] perf record --off-cpu: Dump the remaining samples in BPF's stack trace map Howard Chu
2025-02-13 23:00 ` [PATCH v15 09/10] perf record --off-cpu: Add --off-cpu-thresh option Howard Chu
2025-02-13 23:00 ` [PATCH v15 10/10] perf test: Add direct off-cpu test Howard Chu
2025-02-13 23:04 ` Howard Chu
2025-02-18 19:32 ` Ian Rogers [this message]
2025-02-19 0:58 ` Howard Chu
2025-02-28 16:36 ` [PATCH v15 00/10] perf record --off-cpu: Dump off-cpu samples directly Gautam Menghani
2025-02-28 17:40 ` Howard Chu
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