linux-kernel - Re: [PATCH 1/2] sched: force update of blocked load of idle cpus

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Message-ID: <CAD0t5oPxXc1XARh8puEThJQYfRNFAc2Su0Bj1bDH7_77MVczzA@mail.gmail.com>
Date:   Thu, 9 Nov 2017 11:56:07 -0800
From:   Todd Kjos <tkjos@...roid.com>
To:     Brendan Jackman <brendan.jackman@....com>
Cc:     Vincent Guittot <vincent.guittot@...aro.org>,
        Dietmar Eggemann <dietmar.eggemann@....com>,
        Ingo Molnar <mingo@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        LKML <linux-kernel@...r.kernel.org>,
        Ingo Molnar <mingo@...hat.com>,
        Morten Rasmussen <morten.rasmussen@....com>
Subject: Re: [PATCH 1/2] sched: force update of blocked load of idle cpus

> @@ -8683,6 +8692,10 @@ static void nohz_balancer_kick(void)
>
>         if (test_and_set_bit(NOHZ_BALANCE_KICK, nohz_flags(ilb_cpu)))
>                 return;
> +
> +       if (only_update)
> +               set_bit(NOHZ_STATS_KICK, nohz_flags(ilb_cpu));

Should there be an "else clear_bit(NOHZ_STATS_KICK, nohz_flags(ilb_cpu));" ?

Seems like any time this is called as !only_update, we should stop
inhibiting rebalance. In fact, we should perhaps go a little further
so that an only_update never inhibits rebalance from a concurrent
!only_update.