On Fri, May 12, 2023 at 04:20:19PM -0700, Dixit, Ashutosh wrote:
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.
Sounds good, Dropping the check here in the new revision. Thanks, Umesh
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 >>
