linux-kernel - Re: [RFC] The Linux Scheduler: a Decade of Wasted Cores Report

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Message-ID: <1461575925.3670.25.camel@gmail.com>
Date:	Mon, 25 Apr 2016 11:18:45 +0200
From:	Mike Galbraith <umgwanakikbuti@...il.com>
To:	Brendan Gregg <brendan.d.gregg@...il.com>,
	Jeff Merkey <linux.mdb@...il.com>
Cc:	LKML <linux-kernel@...r.kernel.org>,
	Peter Zijlstra <peterz@...radead.org>
Subject: Re: [RFC] The Linux Scheduler: a Decade of Wasted Cores Report

On Sun, 2016-04-24 at 09:05 +0200, Mike Galbraith wrote:
> On Sat, 2016-04-23 at 18:38 -0700, Brendan Gregg wrote:
> 
> > The bugs they found seem real, and their analysis is great (although
> > using visualizations to find and fix scheduler bugs isn't new), and it
> > would be good to see these fixed. However, it would also be useful to
> > double check how widespread these issues really are. I suspect many on
> > this list can test these patches in different environments.
> 
> Part of it sounded to me very much like they're meeting and "fixing"
> SMP group fairness...

Ew, NUMA boxen look like they could use a hug or two.  Add a group of
one hog to compete with a box wide kbuild, ~lose a node.

Master.today, 4 node box, make -j 192 modules

root group
real    1m6.987s      1.00

cgroup vs 1 group of 1 hog
real    1m20.871s     1.20

cgroup vs 2 groups of 1 hog
real    1m48.803s     1.62

	-Mike