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    SubjectRe: [RFD PATCH 1/4] powerpc: cpu: Reduce the polling interval in __cpu_up()
    On Tue, Jun 16, 2009 at 11:06:45AM -0500, Nathan Lynch wrote:
    > Please cc linuxppc-dev if you want the powerpc maintainer to pick this
    > up.

    Will do it. I still need to test this patch across the different
    configurations. I posted it here just so that we get a rough idea
    regarding what we're looking at.

    Thanks for taking a look at this one!
    > Gautham R Shenoy <> writes:
    > > The cpu online operation on a powerpc today takes order of 200-220ms. Of
    > > this time, approximately 200ms is taken up by __cpu_up(). This is because
    > > we poll every 200ms to check if the new cpu has notified it's presence
    > > through the cpu_callin_map. We poll every 200ms until the new cpu sets
    > > the value in cpu_callin_map or 5 seconds elapse, whichever comes earlier.
    > >
    > > However, the time taken by the new processor to indicate it's presence has
    > > found to be less than a millisecond
    > Only with your particular configuration (which is not identified). It
    > can take much longer than 1ms on others.
    > > Keeping this in mind, reduce the
    > > polling interval from 200ms to 1ms while retaining the 5 second
    > > timeout.
    > Ack on the patch, but the changelog needs work. I assume your
    > observations are from a pseries system -- please state this in the
    > changelog ("powerpc" is too broad), along with the processor model and
    > whether the LPAR's processors were configured in dedicated or shared
    > mode.

    Will send these details with the patch separately Ccing linux-ppcdev list.

    Thanks and Regards

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