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    SubjectRe: slab: start_cpu_timer/cache_reap CONFIG_HOTPLUG_CPU problems
    On 02/20, Christoph Lameter wrote:
    >
    > On Tue, 20 Feb 2007, Max Krasnyansky wrote:
    >
    > > > > Well seems that we have a set of unresolved issues with workqueues and cpu
    > > > > hotplug.
    > >
    > > How about storing 'cpu' explicitly in the work queue instead of relying on the
    > > smp_processor_id() and friends ? That way there is no ambiguity when
    > > threads/timers get
    > > moved around.
    >
    > The slab functionality is designed to work on the processor with the
    > queue. These tricks will only cause more trouble in the future. The
    > cache_reaper needs to be either disabled or run on the right processor. It
    > should never run on the wrong processor.

    I personally agree. Besides, cache_reaper is not alone. Note the comment
    in debug_smp_processor_id() about cpu-bound processes. The slab does correct
    thing right now, stops the timer on CPU_DEAD. Other problems imho should be
    solved by fixing cpu-hotplug. Gautham and Srivatsa are working on that.

    Oleg.

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