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    SubjectRe: [RFC][PATCH] lru_add_drain_all() don't use schedule_on_each_cpu()
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    > On Mon, 2008-10-27 at 12:14 +0900, KOSAKI Motohiro wrote:
    > > > Right, and would be about 4k+sizeof(task_struct), some people might be
    > > > bothered, but most won't care.
    > > >
    > > > > Perhaps, I misunderstand your intension. so can you point your
    > > > > previous discussion url?
    > > >
    > > > my google skillz fail me, but once in a while people complain that we
    > > > have too many kernel threads.
    > > >
    > > > Anyway, if we can re-use this per-cpu workqueue for more goals, I guess
    > > > there is even less of an objection.
    > >
    > > In general, you are right.
    > > but this is special case. mmap_sem is really widely used various subsystem and drivers.
    > > (because page fault via copy_user introduce to depend on mmap_sem)
    > >
    > > Then, any work-queue reu-sing can cause similar dead-lock easily.
    >
    > Yeah, I know, and the cpu-hotplug discussion needed another thread due
    > to yet another locking incident. I was hoping these two could go
    > together.

    Yeah, I found its thread. (I think it is "work_on_cpu: helper for doing task on a CPU.", right?)
    So I'll read it soon.

    Please wait a bit.


    >
    > Neither are general-purpose workqueues, both need to stay away from the
    > normal eventd due to deadlocks.
    >
    > ego, does you extra thread ever use mmap_sem?







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