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From: Namhyung Kim <namhyung@kernel.org>
To: Ian Rogers <irogers@google.com>
Cc: Howard Chu <howardchu95@gmail.com>,
	peterz@infradead.org, mingo@redhat.com, acme@kernel.org,
	mark.rutland@arm.com, alexander.shishkin@linux.intel.com,
	jolsa@kernel.org, adrian.hunter@intel.com,
	kan.liang@linux.intel.com, linux-perf-users@vger.kernel.org,
	linux-kernel@vger.kernel.org,
	Arnaldo Carvalho de Melo <acme@redhat.com>,
	James Clark <james.clark@linaro.org>
Subject: Re: [PATCH v9 01/10] perf record --off-cpu: Add --off-cpu-thresh option
Date: Tue, 10 Dec 2024 10:24:17 -0800	[thread overview]
Message-ID: <Z1iHUTN_T4xZcrgj@google.com> (raw)
In-Reply-To: <CAP-5=fUm6kWmX3FzFYJ_xoBgfgs0zPigyMKLy7VrXvNt1sC+iQ@mail.gmail.com>

On Mon, Dec 09, 2024 at 06:24:21PM -0800, Ian Rogers wrote:
> On Mon, Dec 9, 2024 at 4:09 PM Namhyung Kim <namhyung@kernel.org> wrote:
> >
> > Hi Howard,
> >
> > Sorry for the late review.
> >
> > On Thu, Nov 21, 2024 at 08:38:31PM -0800, Howard Chu wrote:
> > > Specify the threshold for dumping offcpu samples with --off-cpu-thresh,
> > > the unit is us (microsecond). Default value is 500,000us (500ms, 0.5s).
> >
> > I guess we mostly care about more than milli-seconds of off-cpu times.
> > Can we change the unit to msec?
> 
> I wonder if there should be two values, one for the command line and
> one in the code. I think microseconds make most sense in the code, 1ms
> being roughly 1000 context switches. On the command line millisecond
> would align with perf stat's -I option, and as you point out, users
> aren't usually working at the granularity of a microsecond. Having the
> code be microsecond oriented allows the option to have a more precise
> command line option in the future, autotuning, etc.

I'm fine as long as it has a proper suffix for the unit. :)

Thanks,
Namhyung


  reply	other threads:[~2024-12-10 18:24 UTC|newest]

Thread overview: 14+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2024-11-22  4:38 [PATCH v9 00/10] perf record --off-cpu: Dump off-cpu samples directly Howard Chu
2024-11-22  4:38 ` [PATCH v9 01/10] perf record --off-cpu: Add --off-cpu-thresh option Howard Chu
2024-12-10  0:09   ` Namhyung Kim
2024-12-10  2:24     ` Ian Rogers
2024-12-10 18:24       ` Namhyung Kim [this message]
2024-11-22  4:38 ` [PATCH v9 02/10] perf evsel: Expose evsel__is_offcpu_event() for future use Howard Chu
2024-11-22  4:38 ` [PATCH v9 03/10] perf record --off-cpu: Parse off-cpu event Howard Chu
2024-11-22  4:38 ` [PATCH v9 04/10] perf record --off-cpu: Preparation of off-cpu BPF program Howard Chu
2024-11-22  4:38 ` [PATCH v9 05/10] perf record --off-cpu: Dump off-cpu samples in BPF Howard Chu
2024-11-22  4:38 ` [PATCH v9 06/10] perf evsel: Assemble offcpu samples Howard Chu
2024-11-22  4:38 ` [PATCH v9 07/10] perf record --off-cpu: Disable perf_event's callchain collection Howard Chu
2024-11-22  4:38 ` [PATCH v9 08/10] perf script: Display off-cpu samples correctly Howard Chu
2024-11-22  4:38 ` [PATCH v9 09/10] perf record --off-cpu: Dump the remaining samples in BPF's stack trace map Howard Chu
2024-11-22  4:38 ` [PATCH v9 10/10] perf test: Add direct off-cpu test Howard Chu

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