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 <npig...@gmail.com>
Looks good. Were you able to see this make a difference in any of the
tests ?
Reviewed-by: Gautham R. Shenoy <e...@linux.vnet.ibm.com>
> ---
> drivers/cpuidle/cpuidle-powernv.c | 4 +++-
> drivers/cpuidle/cpuidle-pseries.c | 3 ++-
> 2 files changed, 5 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/cpuidle/cpuidle-powernv.c
> b/drivers/cpuidle/cpuidle-powernv.c
> index 79152676f62b..50b3c2e0306f 100644
> --- a/drivers/cpuidle/cpuidle-powernv.c
> +++ b/drivers/cpuidle/cpuidle-powernv.c
> @@ -51,9 +51,10 @@ static int snooze_loop(struct cpuidle_device *dev,
> {
> u64 snooze_exit_time;
>
> - local_irq_enable();
> set_thread_flag(TIF_POLLING_NRFLAG);
>
> + local_irq_enable();
> +
> snooze_exit_time = get_tb() + snooze_timeout;
> ppc64_runlatch_off();
> HMT_very_low();
> @@ -66,6 +67,7 @@ static int snooze_loop(struct cpuidle_device *dev,
> ppc64_runlatch_on();
> clear_thread_flag(TIF_POLLING_NRFLAG);
> smp_mb();
> +
> return index;
> }
>
> diff --git a/drivers/cpuidle/cpuidle-pseries.c
> b/drivers/cpuidle/cpuidle-pseries.c
> index 166ccd711ec9..7b12bb2ea70f 100644
> --- a/drivers/cpuidle/cpuidle-pseries.c
> +++ b/drivers/cpuidle/cpuidle-pseries.c
> @@ -62,9 +62,10 @@ static int snooze_loop(struct cpuidle_device *dev,
> unsigned long in_purr;
> u64 snooze_exit_time;
>
> + set_thread_flag(TIF_POLLING_NRFLAG);
> +
> idle_loop_prolog(&in_purr);
> local_irq_enable();
> - set_thread_flag(TIF_POLLING_NRFLAG);
> snooze_exit_time = get_tb() + snooze_timeout;
>
> while (!need_resched()) {
> --
> 2.11.0
>
