From: Frederic Weisbecker <fweisbec@gmail.com>
To: Mike Galbraith <umgwanakikbuti@gmail.com>
Cc: Ingo Molnar <mingo@kernel.org>,
Peter Zijlstra <peterz@infradead.org>,
Andrew Morton <akpm@linux-foundation.org>,
Alexey Dobriyan <adobriyan@gmail.com>,
linux-kernel@vger.kernel.org, Ingo Molnar <mingo@elte.hu>,
Christoph Lameter <cl@linux.com>
Subject: Re: 4.2.2: NR_CPUS effectively being 1 bug
Date: Sat, 3 Oct 2015 14:31:17 +0200 [thread overview]
Message-ID: <20151003123115.GA6389@lerouge> (raw)
In-Reply-To: <1443873884.3215.2.camel@gmail.com>
On Sat, Oct 03, 2015 at 02:04:44PM +0200, Mike Galbraith wrote:
> On Sat, 2015-10-03 at 10:52 +0200, Ingo Molnar wrote:
> > Ok, looks like a patch with good intentions but bad effects. Mind sending a revert
> > patch, changelogged, signed off?
>
> No. They know.
The reason for this patch is that NO_HZ_FULL is only useful on a CPU if no task
other than the desired one can be scheduled on it. Hence the cpu_isolated_map.
Only those who enable NO_HZ_FULL_ALL by accident do complain, not those who
really use it so far. At least it makes people realize their mistake.
That said I never liked that cpu_isolated_map. And some regular non-isolation
work may be needed to be done even on NO_HZ_FULL_ALL machines and it that
case we get screwed.
So I should revert that and defer that isolation work to explicit affinity
setting or cpusets.
next prev parent reply other threads:[~2015-10-03 12:31 UTC|newest]
Thread overview: 14+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-10-02 20:46 4.2.2: NR_CPUS effectively being 1 bug Alexey Dobriyan
2015-10-02 21:00 ` Andrew Morton
2015-10-03 6:53 ` Peter Zijlstra
2015-10-03 7:38 ` Ingo Molnar
2015-10-03 8:15 ` Mike Galbraith
2015-10-03 8:18 ` Ingo Molnar
2015-10-03 8:24 ` Mike Galbraith
2015-10-03 8:52 ` Ingo Molnar
2015-10-03 12:04 ` Mike Galbraith
2015-10-03 12:31 ` Frederic Weisbecker [this message]
2015-10-03 12:49 ` Mike Galbraith
2015-10-03 12:14 ` Alexey Dobriyan
2015-10-03 12:19 ` Mike Galbraith
2015-10-03 6:50 ` Afzal Mohammed
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