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    SubjectRE: [ia64] Question on __ARCH_WANT_UNLOCKED_CTXSW
    On Wed, 2011-08-24 at 13:46 -0700, Luck, Tony wrote:
    > > happen to remember what the perceived benefit of using
    > > __ARCH_WANT_UNLOCKED_CTXSW was about?
    > No - digging around the code hasn't rung any bells for me either.
    > Perhaps just general goodness for not holding a lock for
    > longer than we need to? But that would imply some case where
    > someone else could do something useful by being able to grab
    > the lock when we drop it. About the only thing I can think
    > of is that it would allow tasks to be re-balanced just a
    > teeny bit earlier --- but re-balancing ought to be somewhat
    > rare, yes?

    Mostly yes, except remote wakeups, however that got a complete overhaul
    in 3.0. Instead of taking the remote rq->lock we now enqueue the task on
    a list and IPI the thing, then let the IPI do the remote enqueue and
    trigger the reschedule.

    So it might make sense to re-evaluate this on ia64 like Ken suggested..
    then again, who has a large ia64 box and is still willing to put time

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