From: Arnaldo Carvalho de Melo <acme@kernel.org>
To: Aditya Gupta <adityag@linux.ibm.com>
Cc: Madadi Vineeth Reddy <vineethr@linux.ibm.com>,
peterz@infradead.org, mingo@redhat.com, namhyung@kernel.org,
mark.rutland@arm.com, alexander.shishkin@linux.intel.com,
jolsa@kernel.org, irogers@google.com, adrian.hunter@intel.com,
linux-perf-users@vger.kernel.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH] perf sched: Rename switches to count and add usage description, options for latency
Date: Fri, 10 May 2024 11:11:36 -0300 [thread overview]
Message-ID: <Zj4rGMsl42_GiDjc@x1> (raw)
In-Reply-To: <3buy7zyybshlphybersfof2acjcbrpxllrcvobizwyse4356nd@7sp74wyxbbfc>
On Thu, May 09, 2024 at 02:49:56PM +0530, Aditya Gupta wrote:
> Hello vineeth,
>
> On Thu, Mar 28, 2024 at 02:30:05PM +0530, Madadi Vineeth Reddy wrote:
> > Rename 'Switches' to 'Count' and document metrics shown for perf
> > sched latency output. Also add options possible with perf sched
> > latency.
> >
> > Initially, after seeing the output of 'perf sched latency', the term
> > 'Switches' seemed like it's the number of context switches-in for a
> > particular task, but upon going through the code, it was observed that
> > it's actually keeping track of number of times a delay was calculated so
> > that it is used in calculation of the average delay.
> >
> > Actually, the switches here is a subset of number of context switches-in
> > because there are some cases where the count is not incremented in
> > switch-in handler 'add_sched_in_event'. For example when a task is
> > switched-in while it's state is not ready to run(!= THREAD_WAIT_CPU).
> >
> > commit d9340c1db3f5 ("perf sched: Display time in milliseconds, reorganize
> > output") changed it from the original count to switches.
> >
> > So, renamed switches to count to make things a bit more clearer and
> > added the metrics description of latency in the document.
> >
> > Signed-off-by: Madadi Vineeth Reddy <vineethr@linux.ibm.com>
>
> Makes sense to me. 'Switches' seems to be context switches, so it might
> be better kept as 'Count' only.
>
> Hence,
>
> Reviewed-by: Aditya Gupta <adityag@linux.ibm.com>
Thanks, applied to perf-tools-next,
- Arnaldo
- Arnaldo
prev parent reply other threads:[~2024-05-10 14:11 UTC|newest]
Thread overview: 4+ messages / expand[flat|nested] mbox.gz Atom feed top
2024-03-28 9:00 [PATCH] perf sched: Rename switches to count and add usage description, options for latency Madadi Vineeth Reddy
2024-04-15 2:31 ` Madadi Vineeth Reddy
2024-05-09 9:19 ` Aditya Gupta
2024-05-10 14:11 ` Arnaldo Carvalho de Melo [this message]
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