On Mon, 23 Feb 2015, r...@redhat.com wrote:

> From: Rik van Riel <r...@redhat.com>
> 
> Ensure that cpus specified with the isolcpus= boot commandline
> option stay outside of the load balancing in the kernel scheduler.
> 
> Operations like load balancing can introduce unwanted latencies,
> which is exactly what the isolcpus= commandline is there to prevent.
> 
> Previously, simply creating a new cpuset, without even touching the
> cpuset.cpus field inside the new cpuset, would undo the effects of
> isolcpus=, by creating a scheduler domain spanning the whole system,
> and setting up load balancing inside that domain. The cpuset root
> cpuset.cpus file is read-only, so there was not even a way to undo
> that effect.
> 
> This does not impact the majority of cpusets users, since isolcpus=
> is a fairly specialized feature used for realtime purposes.
> 
> Cc: Peter Zijlstra <pet...@infradead.org>
> Cc: Clark Williams <willi...@redhat.com>
> Cc: Li Zefan <lize...@huawei.com>
> Cc: Ingo Molnar <mi...@redhat.com>
> Cc: Luiz Capitulino <lcapitul...@redhat.com>
> Cc: cgro...@vger.kernel.org
> Signed-off-by: Rik van Riel <r...@redhat.com>

Tested-by: David Rientjes <rient...@google.com>
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