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    SubjectRe: [PATCH 1/2] cpusets,isolcpus: exclude isolcpus from load balancing in cpusets
    On Wed, Feb 25, 2015 at 11:38:07AM -0500, riel@redhat.com wrote:
    > From: Rik van Riel <riel@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 <peterz@infradead.org>
    > Cc: Clark Williams <williams@redhat.com>
    > Cc: Li Zefan <lizefan@huawei.com>
    > Cc: Ingo Molnar <mingo@redhat.com>
    > Cc: Luiz Capitulino <lcapitulino@redhat.com>
    > Cc: Mike Galbraith <umgwanakikbuti@gmail.com>
    > Cc: cgroups@vger.kernel.org
    > Signed-off-by: Rik van Riel <riel@redhat.com>
    > Tested-by: David Rientjes <rientjes@google.com>

    Might I asked you to update Documentation/cgroups/cpusets.txt with this
    knowledge? While it does mentions isolcpus it does not clarify the
    interaction between it and cpusets.

    Other than that,

    Acked-by: Peter Zijlstra (Intel) <peterz@infradead.org>


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