From: Frederic Weisbecker <frederic@kernel.org>
To: Peter Zijlstra <peterz@infradead.org>
Cc: Vincent Guittot <vincent.guittot@linaro.org>,
mingo@kernel.org, linux-kernel@vger.kernel.org,
valentin.schneider@arm.com, morten.rasmussen@foss.arm.com,
brendan.jackman@arm.com, dietmar.eggemann@arm.com,
Frederic Weisbecker <fweisbec@gmail.com>
Subject: Re: [PATCH v3 3/3] sched: update blocked load when newly idle
Date: Thu, 1 Mar 2018 17:09:20 +0100 [thread overview]
Message-ID: <20180301160918.GC29639@lerouge> (raw)
In-Reply-To: <20180212153805.GW25201@hirez.programming.kicks-ass.net>
On Mon, Feb 12, 2018 at 04:38:05PM +0100, Peter Zijlstra wrote:
> On Mon, Feb 12, 2018 at 03:34:44PM +0100, Vincent Guittot wrote:
> > > Aside from the above being an unreadable mess, I dislike that it breaks
> > > the various isolation crud, we should not touch CPUs outside of our
> > > domain.
> > >
> > >
> > > Maybe something like the below? (unfinished)
> > >
> >
> > good catch. I completely miss the isolation stuff.
> > But isn't already the case when kicking ilb ? I mean that an idle CPU touches
> > all idle CPUs and some can be outside its domain during ilb.
>
> > Shouldn't we test housekeeping_cpu(cpu, HK_FLAG_SCHED) instead if we want to
> > make sure that an isolated/full nohz CPU will not be used for updating blocked
> > load of CPUs outside its domain ?
>
> I _thought_ we had some 'housekeeping' crud in the ilb selection logic,
> but now I can't find it. Frederic?
I think you're referring to nohz_balance_idle(). The call is still there but HK_FLAG_SCHED
is unused for now. I initially turned it on by default on nohz_full but some people
complained. I don't recall why exactly. Anyway I'm waiting for a suitable interface
to use it.
prev parent reply other threads:[~2018-03-01 16:09 UTC|newest]
Thread overview: 13+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-02-12 8:07 [PATCH v3 0/3] sched: Update blocked load Vincent Guittot
2018-02-12 8:07 ` [PATCH v3 1/3] sched: Stop nohz stats when decayed Vincent Guittot
2018-02-12 9:41 ` Peter Zijlstra
2018-02-12 9:52 ` Vincent Guittot
2018-02-12 10:45 ` Peter Zijlstra
2018-02-12 11:02 ` Vincent Guittot
2018-02-12 8:07 ` [PATCH v3 2/3] sched: reduce the periodic update duration Vincent Guittot
2018-02-12 8:07 ` [PATCH v3 3/3] sched: update blocked load when newly idle Vincent Guittot
2018-02-12 12:04 ` Peter Zijlstra
2018-02-12 14:34 ` Vincent Guittot
2018-02-12 15:38 ` Peter Zijlstra
2018-02-12 16:06 ` Vincent Guittot
2018-03-01 16:09 ` Frederic Weisbecker [this message]
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