On Mon, Jun 15, 2020 at 09:31:54PM +0200, Peter Zijlstra wrote:
> On Mon, Jun 15, 2020 at 08:40:41PM +0200, Peter Zijlstra wrote:
>
> > > @@ -186,8 +187,10 @@ int cpuidle_enter_s2idle(struct cpuidle_driver *drv,
> > > struct cpuidle_device *dev)
> > > * be frozen safely.
> > > */
> > > index = find_deepest_state(drv, dev, U64_MAX, 0, true);
> > > - if (index > 0)
> > > + if (index > 0) {
> > > + __current_clr_polling();
> > > enter_s2idle_proper(drv, dev, index);
> > > + }
> > >
> > > return index;
> > > }
> >
> > So how is that commit 08e237fa56a1 not suffient? That makes
> > mwait_idle_with_hints() DTRT for this 'functionally challenged' piece of
> > hardware.
> >
> > AFAICT intel_enter_s2idle() uses mwait_idle_with_hints().
> >
> > What am I missing?
>
> What's missing is that cpuidle_enter_s2idle() doesn't properly match
> call_cpuidle().
>
Right.
> Something like so then. Your version is racy, if someone already set
> TIF_NEED_RESCHED you just clear POLLING and go to sleep.
>
Got it, I'll test the patch below.
Thanks,
Chenyu
> ---
>
> diff --git a/drivers/cpuidle/cpuidle.c b/drivers/cpuidle/cpuidle.c
> index c149d9e20dfd..81bee8d03c6d 100644
> --- a/drivers/cpuidle/cpuidle.c
> +++ b/drivers/cpuidle/cpuidle.c
> @@ -133,8 +133,8 @@ int cpuidle_find_deepest_state(struct cpuidle_driver *drv,
> }
>
> #ifdef CONFIG_SUSPEND
> -static void enter_s2idle_proper(struct cpuidle_driver *drv,
> - struct cpuidle_device *dev, int index)
> +static void s2idle_enter(struct cpuidle_driver *drv,
> + struct cpuidle_device *dev, int index)
> {
> ktime_t time_start, time_end;
>
> @@ -168,6 +168,15 @@ static void enter_s2idle_proper(struct cpuidle_driver
> *drv,
> dev->states_usage[index].s2idle_usage++;
> }
>
> +static int call_s2idle(struct cpuidle_driver *drv, struct cpuidle_device
> *dev,
> + int index)
> +{
> + if (!current_clr_polling_and_test())
> + s2idle_enter(drv, dev, index);
> +
> + return index;
> +}
> +
> /**
> * cpuidle_enter_s2idle - Enter an idle state suitable for suspend-to-idle.
> * @drv: cpuidle driver for the given CPU.
> @@ -187,7 +196,7 @@ int cpuidle_enter_s2idle(struct cpuidle_driver *drv,
> struct cpuidle_device *dev)
> */
> index = find_deepest_state(drv, dev, U64_MAX, 0, true);
> if (index > 0)
> - enter_s2idle_proper(drv, dev, index);
> + call_s2idle(drv, dev, index);
>
> return index;
> }
