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    SubjectRe: idle issues running sembench on 128 cpus II
    On 05/04/2011 06:48 PM, Andi Kleen wrote:
    >> Here's a new patch without the raw. Boots on my Westmere.
    >
    > Sorry appended the old patch. Here's really the new version.
    >
    > From: Andi Kleen<ak@linux.intel.com>
    > Date: Wed, 4 May 2011 15:09:27 -0700
    > Subject: [PATCH] Move C3 stop test outside lock
    >
    > Avoid taking locks in the idle path for systems where the timer
    > doesn't stop in C3.
    >
    > Signed-off-by: Andi Kleen<ak@linux.intel.com>
    >
    > diff --git a/kernel/time/tick-broadcast.c b/kernel/time/tick-broadcast.c
    > index da800ff..7f565b7 100644
    > --- a/kernel/time/tick-broadcast.c
    > +++ b/kernel/time/tick-broadcast.c
    > @@ -456,23 +456,22 @@ void tick_broadcast_oneshot_control(unsigned long reason)
    > unsigned long flags;
    > int cpu;
    >
    > - raw_spin_lock_irqsave(&tick_broadcast_lock, flags);
    > -
    > /*
    > * Periodic mode does not care about the enter/exit of power
    > * states
    > */
    > if (tick_broadcast_device.mode == TICKDEV_MODE_PERIODIC)
    > - goto out;
    > + return;
    >
    > - bc = tick_broadcast_device.evtdev;
    > cpu = smp_processor_id();
    > + bc = tick_broadcast_device.evtdev;
    > td =&per_cpu(tick_cpu_device, cpu);
    > dev = td->evtdev;
    >
    > if (!(dev->features& CLOCK_EVT_FEAT_C3STOP))
    > - goto out;
    > + return;

    out: is now defined but not used in this function.

    >
    > + raw_spin_lock_irqsave(&tick_broadcast_lock, flags);
    > if (reason == CLOCK_EVT_NOTIFY_BROADCAST_ENTER) {
    > if (!cpumask_test_cpu(cpu, tick_get_broadcast_oneshot_mask())) {
    > cpumask_set_cpu(cpu, tick_get_broadcast_oneshot_mask());
    >


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