linux-kernel - Re: [PATCH v14 24/25] sched: early boot clock

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Date:   Thu, 19 Jul 2018 10:16:34 -0400
From:   Pavel Tatashin <pasha.tatashin@...cle.com>
To:     peterz@...radead.org
Cc:     Steven Sistare <steven.sistare@...cle.com>,
        Daniel Jordan <daniel.m.jordan@...cle.com>,
        linux@...linux.org.uk, schwidefsky@...ibm.com,
        Heiko Carstens <heiko.carstens@...ibm.com>,
        John Stultz <john.stultz@...aro.org>, sboyd@...eaurora.org,
        x86@...nel.org, LKML <linux-kernel@...r.kernel.org>,
        mingo@...hat.com, tglx@...utronix.de, hpa@...or.com,
        douly.fnst@...fujitsu.com, prarit@...hat.com, feng.tang@...el.com,
        Petr Mladek <pmladek@...e.com>, gnomes@...rguk.ukuu.org.uk,
        linux-s390@...r.kernel.org, boris.ostrovsky@...cle.com,
        jgross@...e.com, pbonzini@...hat.com
Subject: Re: [PATCH v14 24/25] sched: early boot clock

On Thu, Jul 19, 2018 at 6:40 AM Peter Zijlstra <peterz@...radead.org> wrote:
>
> On Tue, Jul 17, 2018 at 10:22:10PM -0400, Pavel Tatashin wrote:
>
> > diff --git a/kernel/sched/clock.c b/kernel/sched/clock.c
> > index 0e9dbb2d9aea..7a8a63b940ee 100644
> > --- a/kernel/sched/clock.c
> > +++ b/kernel/sched/clock.c
> > @@ -202,7 +202,15 @@ static void __sched_clock_gtod_offset(void)
> >
> >  void __init sched_clock_init(void)
> >  {
> > +     unsigned long flags;
> > +
> >       sched_clock_running = 1;
> > +
> > +     /* Adjust __gtod_offset for contigious transition from early clock */
> > +     local_irq_save(flags);
> > +     sched_clock_tick();
> > +     local_irq_restore(flags);
> > +     __sched_clock_gtod_offset();
>
> I think we want to keep __sched_clock_gtod_offset() inside the IRQ
> disabled region.

Fixed.

>
> And I just looked at my patch:
>
>   https://lkml.kernel.org/r/20180626090003.GA2458@hirez.programming.kicks-ass.net
>
> and that had a comment about how we wanted to set the gtod offset
> _before_ setting sched_clock_running, yet here you do it the other way
> around. Hmm?

Fixed, and added your comment.

Thank you,
Pavel