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.
next prev parent 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
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