Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
MIME-Version: 1.0
References: <20200820120025.74460-1-benbjiang@tencent.com> <CAKfTPtABCbEuYf3uup5ZODyPXpUqBjgM8A5gBQqM0cQGxWk5zw@mail.gmail.com>
 <20200820125829.GT2674@hirez.programming.kicks-ass.net> <CAKfTPtBuZOb9-W5sS=DqxcuMFa8Lw=7XqMJ_YrXEgd5zvufYjA@mail.gmail.com>
 <20200820134341.GW2674@hirez.programming.kicks-ass.net>
In-Reply-To: <20200820134341.GW2674@hirez.programming.kicks-ass.net>
From:   Vincent Guittot <vincent.guittot@linaro.org>
Date:   Thu, 20 Aug 2020 16:09:17 +0200
Message-ID: <CAKfTPtC203mVB6QB1APbZ5igavdcwbJsCQH_8K__rhGxi+KXoQ@mail.gmail.com>
Subject: Re: [PATCH] sched/fair: avoid vruntime compensation for SCHED_IDLE task
To:     Peter Zijlstra <peterz@infradead.org>
Cc:     Jiang Biao <benbjiang@gmail.com>, Ingo Molnar <mingo@redhat.com>,
        Juri Lelli <juri.lelli@redhat.com>,
        Dietmar Eggemann <dietmar.eggemann@arm.com>,
        Steven Rostedt <rostedt@goodmis.org>,
        Ben Segall <bsegall@google.com>, Mel Gorman <mgorman@suse.de>,
        linux-kernel <linux-kernel@vger.kernel.org>,
        Jiang Biao <benbjiang@tencent.com>
Content-Type: text/plain; charset="UTF-8"
Sender: linux-kernel-owner@vger.kernel.org
Precedence: bulk

On Thu, 20 Aug 2020 at 15:44, <peterz@infradead.org> wrote:
>
> > That's been said, not compensating the vruntime for a sched_idle task
> > makes sense for me. Even if that will only help for others task in the
> > same cfs_rq
>
> Yeah, but it is worth the extra pointer chasing and branches?

For that I let Jiang provides figures to show the worthful

>
> Then again, I suppose we started all that with the idle_h_nr_running
> nonsense :/