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    SubjectRe: [PATCH] x86,sched: Fix sched_smt_power_savings totally broken
    On 10 January 2012 02:54, Suresh Siddha <> wrote:
    > On Mon, 2012-01-09 at 15:29 +0100, Vincent Guittot wrote:
    >> Hi Peter,
    >> I'm also using sched_mc level for doing powersaving load balance on
    >> ARM platform and we have real benefits.
    > hi Vincent, Can you elaborate on your platform topology where you see
    > the benefits?

    Hi Suresh,

    I'm using dual/quad cores ARM platform. When sched_mc is different
    from 0, the topology is changed from 1 socket/cluster to 2 virtual
    sockets/clusters with 1 or 2 cores in each cluster. For low cpu load
    situation, the tasks are gathered in 1 virtual socket and let the
    cores in the other socket to enter idle state thanks to cpuidle. On
    ARM platform, cores in a cluster can enter interesting idle state even
    if the complete cluster can't reach a deep idle state.
    With dual cores platform, i'm increasing the cpu_power to gather tasks
    on 1 core when cores are at lowest frequency. In fact i'm detecting a
    low cpu load (only small tasks are running) and ensure that these
    small tasks are kept on 1 core.


    > on x86, 'sched_mc' was designed for the case of consolidating load into
    > one socket before using another idle socket.
    > Just wondering if this is your use case too or if you are consolidating
    > at a different topological level.
    > thanks,
    > suresh

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