Re: [patch v2 1/2] sched: Use resched IPI to kick off the nohz idlebalance

From: Peter Zijlstra
Date: Tue Oct 04 2011 - 05:06:27 EST


On Mon, 2011-10-03 at 15:09 -0700, Suresh Siddha wrote:
> + smp_mb();
> + /*
> + * Use smp_send_reschedule() instead of resched_cpu().
> + * This way we generate a sched IPI on the target cpu which
> + * is idle. And the softirq performing nohz idle load balance
> + * will be run before returning from the IPI.
> + */
> + smp_send_reschedule(ilb_cpu);

Now the only thing missing is where the matching barrier is, does
receiving an interrupt imply a mb? If so that wants mentioning
somewhere, otherwise people will wonder how we can ever read the right
value.


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