linux-kernel.vger.kernel.org archive mirror
 help / color / mirror / Atom feed
From: Peter Zijlstra <peterz@infradead.org>
To: Ingo Molnar <mingo@kernel.org>
Cc: Frederic Weisbecker <frederic@kernel.org>,
	LKML <linux-kernel@vger.kernel.org>,
	Jacek Anaszewski <jacek.anaszewski@gmail.com>,
	Wanpeng Li <wanpengli@tencent.com>,
	"Rafael J . Wysocki" <rjw@rjwysocki.net>,
	Benjamin Herrenschmidt <benh@kernel.crashing.org>,
	Rik van Riel <riel@surriel.com>,
	Thomas Gleixner <tglx@linutronix.de>,
	Yauheni Kaliuta <yauheni.kaliuta@redhat.com>,
	Viresh Kumar <viresh.kumar@linaro.org>,
	Pavel Machek <pavel@ucw.cz>
Subject: Re: [PATCH 1/6] sched/cputime: Support other fields on kcpustat_field()
Date: Wed, 20 Nov 2019 22:04:40 +0100	[thread overview]
Message-ID: <20191120210440.GR3079@worktop.programming.kicks-ass.net> (raw)
In-Reply-To: <20191120115142.GA89662@gmail.com>

On Wed, Nov 20, 2019 at 12:51:42PM +0100, Ingo Molnar wrote:
> * Frederic Weisbecker <frederic@kernel.org> wrote:

> > +		/*
> > +		 * Nice VS unnice cputime accounting may be inaccurate if
> > +		 * the nice value has changed since the last vtime update.
> > +		 * But proper fix would involve interrupting target on nice
> > +		 * updates which is a no go on nohz_full.
> 
> Well, we actually already interrupt the target in both sys_nice() and 
> sys_setpriority() etc. syscall variants: we call set_user_nice() which 
> calls resched_curr() and the task is sent an IPI and runs through a 
> reschedule.

I think we can easily avoid doing that IPI when we find it is the only
task on that runqueue. Which is exactly the case for NOHZ_FULL.


  reply	other threads:[~2019-11-20 21:05 UTC|newest]

Thread overview: 12+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2019-11-19 23:22 [PATCH 0/6] sched/nohz: Make the rest of kcpustat vtime aware v2 Frederic Weisbecker
2019-11-19 23:22 ` [PATCH 1/6] sched/cputime: Support other fields on kcpustat_field() Frederic Weisbecker
2019-11-20 11:51   ` Ingo Molnar
2019-11-20 21:04     ` Peter Zijlstra [this message]
2019-11-19 23:22 ` [PATCH 2/6] sched/vtime: Bring all-in-one kcpustat accessor for vtime fields Frederic Weisbecker
2019-11-20 12:04   ` Ingo Molnar
2019-11-20 15:00     ` Frederic Weisbecker
2019-11-19 23:22 ` [PATCH 3/6] procfs: Use all-in-one vtime aware kcpustat accessor Frederic Weisbecker
2019-11-19 23:22 ` [PATCH 4/6] cpufreq: Use vtime aware kcpustat accessors for user time Frederic Weisbecker
2019-11-19 23:22 ` [PATCH 5/6] leds: Use all-in-one vtime aware kcpustat accessor Frederic Weisbecker
2019-11-19 23:22 ` [PATCH 6/6] rackmeter: Use " Frederic Weisbecker
2019-11-21  2:44 [PATCH 0/6] sched/nohz: Make the rest of kcpustat vtime aware v3 Frederic Weisbecker
2019-11-21  2:44 ` [PATCH 1/6] sched/cputime: Support other fields on kcpustat_field() Frederic Weisbecker

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=20191120210440.GR3079@worktop.programming.kicks-ass.net \
    --to=peterz@infradead.org \
    --cc=benh@kernel.crashing.org \
    --cc=frederic@kernel.org \
    --cc=jacek.anaszewski@gmail.com \
    --cc=linux-kernel@vger.kernel.org \
    --cc=mingo@kernel.org \
    --cc=pavel@ucw.cz \
    --cc=riel@surriel.com \
    --cc=rjw@rjwysocki.net \
    --cc=tglx@linutronix.de \
    --cc=viresh.kumar@linaro.org \
    --cc=wanpengli@tencent.com \
    --cc=yauheni.kaliuta@redhat.com \
    --subject='Re: [PATCH 1/6] sched/cputime: Support other fields on kcpustat_field()' \
    /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

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).