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

On Mon, 12 Jun 2017 20:40:25 +0530
Gautham R Shenoy [off-list ref] wrote:

On Mon, Jun 12, 2017 at 09:58:31AM +1000, Nicholas Piggin wrote:

quoted

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@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