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From:   Chen Yu <yu.chen.surf@gmail.com>
Date:   Sun, 19 Apr 2020 23:31:31 +0800
Message-ID: <CADjb_WQ0rg1O9t8hkevUmf_Yx4mTRZ0O_Wz-p3VN8oDbGVBuJA@mail.gmail.com>
Subject: Re: [RFC PATCH 07/13] sched: Add core wide task selection and scheduling.
To:     Peter Zijlstra <peterz@infradead.org>
Cc:     vpillai <vpillai@digitalocean.com>,
        Nishanth Aravamudan <naravamudan@digitalocean.com>,
        Julien Desfossez <jdesfossez@digitalocean.com>,
        Tim Chen <tim.c.chen@linux.intel.com>,
        Ingo Molnar <mingo@kernel.org>,
        Thomas Gleixner <tglx@linutronix.de>,
        Paul Turner <pjt@google.com>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
        fweisbec@gmail.com, Kees Cook <keescook@chromium.org>,
        Greg Kerr <kerrnel@google.com>, Phil Auld <pauld@redhat.com>,
        Aaron Lu <aaron.lwe@gmail.com>,
        Aubrey Li <aubrey.intel@gmail.com>,
        Aubrey Li <aubrey.li@linux.intel.com>,
        Valentin Schneider <valentin.schneider@arm.com>,
        Mel Gorman <mgorman@techsingularity.net>,
        Pawan Gupta <pawan.kumar.gupta@linux.intel.com>,
        Paolo Bonzini <pbonzini@redhat.com>,
        Joel Fernandes <joelaf@google.com>, joel@joelfernandes.org,
        Aaron Lu <aaron.lu@linux.alibaba.com>,
        Long Cui <long.cui@intel.com>
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On Fri, Apr 17, 2020 at 7:18 PM Peter Zijlstra <peterz@infradead.org> wrote:
>
> On Thu, Apr 16, 2020 at 11:39:05AM +0800, Chen Yu wrote:
>
> > diff --git a/kernel/sched/core.c b/kernel/sched/core.c
> > index 02495d44870f..ef101a3ef583 100644
> > --- a/kernel/sched/core.c
> > +++ b/kernel/sched/core.c
> > @@ -4477,9 +4477,14 @@ pick_next_task(struct rq *rq, struct task_struct *prev, struct rq_flags *rf)
> >               return next;
> >       }
> >
> > -     prev->sched_class->put_prev_task(rq, prev);
> > -     if (!rq->nr_running)
> > -             newidle_balance(rq, rf);
> > +
> > +#ifdef CONFIG_SMP
> > +     for_class_range(class, prev->sched_class, &idle_sched_class) {
> > +             if (class->balance(rq, prev, rf))
> > +                     break;
> > +     }
> > +#endif
> > +     put_prev_task(rq, prev);
> >
> >       smt_mask = cpu_smt_mask(cpu);
>
> Instead of duplicating that, how about you put the existing copy in a
> function to share? finish_prev_task() perhaps?
>
> Also, can you please make newidle_balance() static again; I forgot doing
> that in 6e2df0581f56, which would've made you notice this sooner I
> suppose.
Okay, I'll do that,

Thanks,
Chenyu