On Fri, 12 May 2023 15:44:00 -0700, Umesh Nerlige Ramappa wrote: > > On Fri, May 12, 2023 at 03:29:03PM -0700, Dixit, Ashutosh wrote: > > On Fri, 05 May 2023 17:58:14 -0700, Umesh Nerlige Ramappa wrote: > >> > > > > Hi Umesh/Tvrtko, > > > >> From: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx> > >> > >> We do not want to have timers per tile and waste CPU cycles and energy via > >> multiple wake-up sources, for a relatively un-important task of PMU > >> sampling, so keeping a single timer works well. But we also do not want > >> the first GT which goes idle to turn off the timer. > >> > >> Add some reference counting, via a mask of unparked GTs, to solve this. > >> > >> Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@xxxxxxxxx> > >> Signed-off-by: Umesh Nerlige Ramappa <umesh.nerlige.ramappa@xxxxxxxxx> > >> --- > >> drivers/gpu/drm/i915/i915_pmu.c | 12 ++++++++++-- > >> drivers/gpu/drm/i915/i915_pmu.h | 4 ++++ > >> 2 files changed, 14 insertions(+), 2 deletions(-) > >> > >> diff --git a/drivers/gpu/drm/i915/i915_pmu.c b/drivers/gpu/drm/i915/i915_pmu.c > >> index 2b63ee31e1b3..669a42e44082 100644 > >> --- a/drivers/gpu/drm/i915/i915_pmu.c > >> +++ b/drivers/gpu/drm/i915/i915_pmu.c > >> @@ -251,7 +251,9 @@ void i915_pmu_gt_parked(struct intel_gt *gt) > >> * Signal sampling timer to stop if only engine events are enabled and > >> * GPU went idle. > >> */ > >> - pmu->timer_enabled = pmu_needs_timer(pmu, false); > >> + pmu->unparked &= ~BIT(gt->info.id); > >> + if (pmu->unparked == 0) > >> + pmu->timer_enabled = pmu_needs_timer(pmu, false); > >> > >> spin_unlock_irq(&pmu->lock); > >> } > >> @@ -268,7 +270,10 @@ void i915_pmu_gt_unparked(struct intel_gt *gt) > >> /* > >> * Re-enable sampling timer when GPU goes active. > >> */ > >> - __i915_pmu_maybe_start_timer(pmu); > >> + if (pmu->unparked == 0) > >> + __i915_pmu_maybe_start_timer(pmu); > >> + > >> + pmu->unparked |= BIT(gt->info.id); > >> > >> spin_unlock_irq(&pmu->lock); > >> } > >> @@ -438,6 +443,9 @@ static enum hrtimer_restart i915_sample(struct hrtimer *hrtimer) > >> */ > >> > >> for_each_gt(gt, i915, i) { > >> + if (!(pmu->unparked & BIT(i))) > >> + continue; > >> + > > > > This is not correct. In this series we are at least sampling frequencies > > (calling frequency_sample) even when GT is parked. So these 3 lines should be > > deleted. engines_sample will get called and will return without doing > > anything if engine events are disabled. > > Not sure I understand. This is checking pmu->'un'parked bits. Sorry, my bad. Not "engines_sample will get called and will return without doing anything if engine events are disabled" but "engines_sample will get called and will return without doing anything if GT is not awake". This is the same as the previous behavior before this series. Umesh and I discussed this but writing this out in case Tvrtko takes a look. Thanks. -- Ashutosh > > > > > >> engines_sample(gt, period_ns); > >> > >> if (i == 0) /* FIXME */ > >> diff --git a/drivers/gpu/drm/i915/i915_pmu.h b/drivers/gpu/drm/i915/i915_pmu.h > >> index a686fd7ccedf..3a811266ac6a 100644 > >> --- a/drivers/gpu/drm/i915/i915_pmu.h > >> +++ b/drivers/gpu/drm/i915/i915_pmu.h > >> @@ -76,6 +76,10 @@ struct i915_pmu { > >> * @lock: Lock protecting enable mask and ref count handling. > >> */ > >> spinlock_t lock; > >> + /** > >> + * @unparked: GT unparked mask. > >> + */ > >> + unsigned int unparked; > >> /** > >> * @timer: Timer for internal i915 PMU sampling. > >> */ > >> -- > >> 2.36.1 > >>