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Message-ID: <ZerkZ/4wpjLrYtvD@gmail.com>
Date: Fri, 8 Mar 2024 11:11:51 +0100
From: Ingo Molnar <mingo@...nel.org>
To: Vincent Guittot <vincent.guittot@...aro.org>
Cc: linux-kernel@...r.kernel.org, Shrikanth Hegde <sshegde@...ux.ibm.com>,
Peter Zijlstra <peterz@...radead.org>,
Dietmar Eggemann <dietmar.eggemann@....com>,
Linus Torvalds <torvalds@...ux-foundation.org>,
Valentin Schneider <vschneid@...hat.com>
Subject: Re: [PATCH 5/9] sched/balancing: Fix comments (trying to) refer to
NOHZ_BALANCE_KICK
* Vincent Guittot <vincent.guittot@...aro.org> wrote:
> On Mon, 4 Mar 2024 at 10:48, Ingo Molnar <mingo@...nel.org> wrote:
> >
> > Fix two typos:
> >
> > - There's no such thing as 'nohz_balancing_kick', the
> > flag is named 'BALANCE' and is capitalized: NOHZ_BALANCE_KICK.
> >
> > - Likewise there's no such thing as a 'pending nohz_balance_kick'
> > either, the NOHZ_BALANCE_KICK flag is all upper-case.
> >
> > Signed-off-by: Ingo Molnar <mingo@...nel.org>
> > Cc: Peter Zijlstra <peterz@...radead.org>
> > Cc: Vincent Guittot <vincent.guittot@...aro.org>
> > Cc: Dietmar Eggemann <dietmar.eggemann@....com>
> > Cc: Linus Torvalds <torvalds@...ux-foundation.org>
> > Cc: Valentin Schneider <vschneid@...hat.com>
> > ---
> > kernel/sched/fair.c | 4 ++--
> > 1 file changed, 2 insertions(+), 2 deletions(-)
> >
> > diff --git a/kernel/sched/fair.c b/kernel/sched/fair.c
> > index 934ace69eb30..4c46bffb6a7a 100644
> > --- a/kernel/sched/fair.c
> > +++ b/kernel/sched/fair.c
> > @@ -12410,14 +12410,14 @@ static int newidle_balance(struct rq *this_rq, struct rq_flags *rf)
> >
> > /*
> > * run_rebalance_domains is triggered when needed from the scheduler tick.
> > - * Also triggered for nohz idle balancing (with nohz_balancing_kick set).
>
> I think it should be nohz_balancer_kick() instead of nohz_balancing_kick
>
>
> > + * Also triggered for NOHZ idle balancing (with NOHZ_BALANCE_KICK set).
>
> In fact, this can be triggered even without NOHZ_BALANCE_KICK. Any of
> the below can trigger this
> - NOHZ_BALANCE_KICK
> - NOHZ_STATS_KICK
> - NOHZ_NEXT_KICK
Yeah, indeed any of the flags in NOHZ_KICK_MASK can trigger nohz_csd and
indirect the balancing softirq - so I changed the text to:
/*
* This softirq may be triggered from the scheduler tick, or by
* any of the flags in NOHZ_KICK_MASK: NOHZ_BALANCE_KICK,
* NOHZ_STATS_KICK or NOHZ_NEXT_KICK.
*/
static __latent_entropy void run_rebalance_domains(struct softirq_action *h)
Thanks,
Ingo
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