linux-kernel - Re: CONFIG_NO_HZ_FULL restricts cpu usage to the equivalent of one in 4.2

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Message-ID: <20150716003419.GB15221@milliways>
Date:	Thu, 16 Jul 2015 01:34:19 +0100
From:	Ken Moffat <zarniwhoop@...world.com>
To:	Andy Lutomirski <luto@...capital.net>
Cc:	linux-kernel@...r.kernel.org, Jeff Epler <jepler@...ythonic.net>,
	Frédéric Weisbecker <fweisbec@...il.com>,
	Rik van Riel <riel@...hat.com>
Subject: Re: CONFIG_NO_HZ_FULL restricts cpu usage to the equivalent of one
 in 4.2

On Wed, Jul 15, 2015 at 12:05:05PM -0700, Andy Lutomirski wrote:
> 
> Before going nuts bisecting, it could be worth running perf record -a -g -e
> cycles (or perhaps -e task-clock instead of -e cycles).  It could also be
> worth manually sampling /proc/PID/stack a few times for a process that isn't
> making as much progress as it should.
> 
> --Andy

I think Frederic has already spotted the problem - in the early
bisects, everything was building on CPU 0.  But thanks for the
suggestion.

ĸen
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This one goes up to eleven!
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