Re: [PATCH 0/2] cpusets,isolcpus: resolve conflict between cpusets and isolcpus

From: Mike Galbraith
Date: Mon Feb 23 2015 - 21:18:52 EST


On Mon, 2015-02-23 at 16:45 -0500, riel@xxxxxxxxxx wrote:
> 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.

3/3: nohz_full cpus become part of that unified isolated map?

-Mike

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