[PATCH 10/14] powerpc/64s: cpuidle set polling before enabling irqs

[Nicholas Piggin]

On Mon, 12 Jun 2017 20:40:25 +0530
Gautham R Shenoy <ego at linux.vnet.ibm.com> wrote:

> On Mon, Jun 12, 2017 at 09:58:31AM +1000, Nicholas Piggin wrote:
> > local_irq_enable can cause interrupts to be taken which could
> > take significant amount of processing time. The idle process
> > should set its polling flag before this, so another process that
> > wakes it during this time will not have to send an IPI.
> > 
> > Expand the TIF_POLLING_NRFLAG coverage to as large as possible.
> > 
> > Signed-off-by: Nicholas Piggin <npiggin at gmail.com>  
> 
> Looks good. Were you able to see this make a difference in any of the
> tests ?

No I didn't measure a difference or have a test case where this was
noticable. I think on a workload with some IO interrupts as well as
cross-CPU wakeups, then statistically we should see some improvement
in IPI rates with this patch.

Thanks,
Nick