On Fri, 05 May 2023 17:58:14 -0700, Umesh Nerlige Ramappa wrote: > Hi Umesh/Tvrtko,
> From: Tvrtko Ursulin <tvrtko.ursu...@intel.com> > > 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.ursu...@intel.com> > Signed-off-by: Umesh Nerlige Ramappa <umesh.nerlige.rama...@intel.com> > --- > 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. 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 >