Re: [PATCH 4/6] drm/i915/pmu: Add reference counting to the sampling timer

[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

 



On Fri, May 05, 2023 at 05:58:14PM -0700, Umesh Nerlige Ramappa wrote:
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.

Looks like the previous patch is a prep work for this one. I would mention something about this patch in the previous patch, but then I am not sure what's the norm in these scenarios. Recently I created some IGT patches that are prep work and refer to future patches in the series.

As is, this patch is
Reviewed-by: Umesh Nerlige Ramappa <umesh.nerlige.ramappa@xxxxxxxxx>

Thanks,
Umesh


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;
+
		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




[Index of Archives]     [AMD Graphics]     [Linux USB Devel]     [Linux Audio Users]     [Yosemite News]     [Linux Kernel]     [Linux SCSI]

  Powered by Linux