linux-kernel - Re: [PATCH V2 0/8] cpusets: Isolate CPUs via sysfs using cpusets

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Message-ID: <1396773020.11763.17.camel@marge.simpson.net>
Date:	Sun, 06 Apr 2014 10:30:20 +0200
From:	Mike Galbraith <umgwanakikbuti@...il.com>
To:	Viresh Kumar <viresh.kumar@...aro.org>
Cc:	tglx@...utronix.de, fweisbec@...il.com, peterz@...radead.org,
	mingo@...nel.org, tj@...nel.org, lizefan@...wei.com,
	linaro-kernel@...ts.linaro.org, linaro-networking@...aro.org,
	Arvind.Chauhan@....com, linux-kernel@...r.kernel.org,
	cgroups@...r.kernel.org
Subject: Re: [PATCH V2 0/8] cpusets: Isolate CPUs via sysfs using cpusets

On Fri, 2014-04-04 at 14:05 +0530, Viresh Kumar wrote: 
> We need to migrate away all the background kernel activities (Unbound) for
> systems requiring isolation of cores (HPC, Real time, networking, etc). After
> creating cpusets, you can write 1 or 0 to cpuset.quiesce file.

I wonder if adding a quiesce switch is really necessary.

Seems to me that if you don't have load balancing turned off, you can't
be very concerned about perturbation, so this should be tied into the
load balancing on/off switch as an extension to isolating cores from the
#1 perturbation source, the scheduler.

I also didn't notice a check for is_cpu_exclusive() at a glance, which
would be a bug, but one that would go away if this additional isolation
were coupled to the existing isolation switch.

-Mike

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