lkml.org 
[lkml]   [2011]   [Sep]   [13]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    SubjectRE: [ia64] Question on __ARCH_WANT_UNLOCKED_CTXSW
    From
    Date
    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
    in?


    \
     
     \ /
      Last update: 2011-09-13 21:01    [W:0.028 / U:0.012 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site