From: Wanpeng Li <kernellwp@gmail.com>
To: Viresh Kumar <viresh.kumar@linaro.org>
Cc: Ingo Molnar <mingo@redhat.com>,
Peter Zijlstra <peterz@infradead.org>,
LKML <linux-kernel@vger.kernel.org>,
Vincent Guittot <vincent.guittot@linaro.org>,
Todd Kjos <tkjos@google.com>,
Daniel Lezcano <daniel.lezcano@linaro.org>,
quentin.perret@linaro.org, chris.redpath@arm.com,
steven.sistare@oracle.com, subhra.mazumdar@oracle.com,
songliubraving@fb.com
Subject: Re: [PATCH V3 0/2] sched/fair: Fallback to sched-idle CPU in absence of idle CPUs
Date: Tue, 10 Dec 2019 19:15:34 +0800 [thread overview]
Message-ID: <CANRm+Czph-WDBm+L8+ykq4FZahsX3fWFV=n8_NwQJQwHoUHoWg@mail.gmail.com> (raw)
In-Reply-To: <20191210063303.pubbpu77ah2veuj7@vireshk-i7>
On Tue, 10 Dec 2019 at 14:33, Viresh Kumar <viresh.kumar@linaro.org> wrote:
>
> On 09-12-19, 11:50, Wanpeng Li wrote:
> > On Wed, 26 Jun 2019 at 13:07, Viresh Kumar <viresh.kumar@linaro.org> wrote:
> > >
> > > Hi,
> > >
> > > We try to find an idle CPU to run the next task, but in case we don't
> > > find an idle CPU it is better to pick a CPU which will run the task the
> > > soonest, for performance reason.
> > >
> > > A CPU which isn't idle but has only SCHED_IDLE activity queued on it
> > > should be a good target based on this criteria as any normal fair task
> > > will most likely preempt the currently running SCHED_IDLE task
> > > immediately. In fact, choosing a SCHED_IDLE CPU over a fully idle one
> > > shall give better results as it should be able to run the task sooner
> > > than an idle CPU (which requires to be woken up from an idle state).
> > >
> > > This patchset updates both fast and slow paths with this optimization.
> > >
> > > Testing is done with the help of rt-app currently and here are the
> > > details:
> > >
> > > - Tested on Octacore Hikey platform (all CPUs change frequency
> > > together).
> > >
> > > - rt-app json [1] creates few tasks and we monitor the scheduling
> > > latency for them by looking at "wu_lat" field (usec).
> > >
> > > - The histograms are created using
> > > https://github.com/adkein/textogram: textogram -a 0 -z 1000 -n 10
> > >
> > > - the stats are accumulated using: https://github.com/nferraz/st
> >
> > Hi Viresh,
> >
> > Thanks for the great work! Could you give the whole commad-line for us testing?
>
> The rt-app json [1] can be run using:
>
> $ rt-app sched-idle.json
>
> This will create couple of files named rt-app-cfs_thread-*.log and
> rt-app-idle_thread-*.log. I looked mostly at the cfs files here as that's what
> we were looking for. We will be interested only in the last column of these
> files, which says "wu_lat". Remove everything apart from that column (and remove
> the first row as well, which has field names) from all cfs files (or write a
> sed/awk command to do it for you.
>
> After that I you can generate the numbers (mean/max/min/etc) using:
>
> $ st rt-app-cfs_thread-*.log
Thanks for pointing out this.
Wanpeng
prev parent reply other threads:[~2019-12-10 11:15 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-06-26 5:06 [PATCH V3 0/2] sched/fair: Fallback to sched-idle CPU in absence of idle CPUs Viresh Kumar
2019-06-26 5:06 ` [PATCH V3 1/2] sched: Start tracking SCHED_IDLE tasks count in cfs_rq Viresh Kumar
2019-07-25 16:15 ` [tip:sched/core] sched/fair: " tip-bot for Viresh Kumar
2019-06-26 5:06 ` [PATCH V3 2/2] sched/fair: Fallback to sched-idle CPU if idle CPU isn't found Viresh Kumar
2019-06-29 1:16 ` Subhra Mazumdar
2019-07-01 8:03 ` Viresh Kumar
2019-07-01 22:08 ` Subhra Mazumdar
2019-07-02 8:35 ` Peter Zijlstra
2019-07-02 16:32 ` Subhra Mazumdar
2019-07-25 16:16 ` [tip:sched/core] sched/fair: Fall back " tip-bot for Viresh Kumar
2019-07-01 13:43 ` [PATCH V3 0/2] sched/fair: Fallback to sched-idle CPU in absence of idle CPUs Peter Zijlstra
2019-07-03 9:13 ` Viresh Kumar
2019-12-09 3:50 ` Wanpeng Li
2019-12-10 6:33 ` Viresh Kumar
2019-12-10 11:15 ` Wanpeng Li [this message]
Reply instructions:
You may reply publicly to this message via plain-text email
using any one of the following methods:
* Save the following mbox file, import it into your mail client,
and reply-to-all from there: mbox
Avoid top-posting and favor interleaved quoting:
https://en.wikipedia.org/wiki/Posting_style#Interleaved_style
* Reply using the --to, --cc, and --in-reply-to
switches of git-send-email(1):
git send-email \
--in-reply-to='CANRm+Czph-WDBm+L8+ykq4FZahsX3fWFV=n8_NwQJQwHoUHoWg@mail.gmail.com' \
--to=kernellwp@gmail.com \
--cc=chris.redpath@arm.com \
--cc=daniel.lezcano@linaro.org \
--cc=linux-kernel@vger.kernel.org \
--cc=mingo@redhat.com \
--cc=peterz@infradead.org \
--cc=quentin.perret@linaro.org \
--cc=songliubraving@fb.com \
--cc=steven.sistare@oracle.com \
--cc=subhra.mazumdar@oracle.com \
--cc=tkjos@google.com \
--cc=vincent.guittot@linaro.org \
--cc=viresh.kumar@linaro.org \
/path/to/YOUR_REPLY
https://kernel.org/pub/software/scm/git/docs/git-send-email.html
* If your mail client supports setting the In-Reply-To header
via mailto: links, try the mailto: link
Be sure your reply has a Subject: header at the top and a blank line
before the message body.
This is a public inbox, see mirroring instructions
for how to clone and mirror all data and code used for this inbox;
as well as URLs for NNTP newsgroup(s).