diff mbox series

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

Message ID 20230513015545.2807282-5-umesh.nerlige.ramappa@intel.com (mailing list archive)
State New, archived
Headers show
Series Add MTL PMU support for multi-gt | expand

Commit Message

Umesh Nerlige Ramappa May 13, 2023, 1:55 a.m. UTC
From: Tvrtko Ursulin <tvrtko.ursulin@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.

v2: Drop the check for unparked in i915_sample (Ashutosh)

Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
Reviewed-by: Umesh Nerlige Ramappa <umesh.nerlige.ramappa@intel.com>
Signed-off-by: Umesh Nerlige Ramappa <umesh.nerlige.ramappa@intel.com>
---
 drivers/gpu/drm/i915/i915_pmu.c | 9 +++++++--
 drivers/gpu/drm/i915/i915_pmu.h | 4 ++++
 2 files changed, 11 insertions(+), 2 deletions(-)

Comments

Dixit, Ashutosh May 13, 2023, 3:01 a.m. UTC | #1
On Fri, 12 May 2023 18:55:43 -0700, Umesh Nerlige Ramappa wrote:
>
> From: Tvrtko Ursulin <tvrtko.ursulin@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.
>
> v2: Drop the check for unparked in i915_sample (Ashutosh)

Reviewed-by: Ashutosh Dixit <ashutosh.dixit@intel.com>

>
> Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
> Reviewed-by: Umesh Nerlige Ramappa <umesh.nerlige.ramappa@intel.com>
> Signed-off-by: Umesh Nerlige Ramappa <umesh.nerlige.ramappa@intel.com>
> ---
>  drivers/gpu/drm/i915/i915_pmu.c | 9 +++++++--
>  drivers/gpu/drm/i915/i915_pmu.h | 4 ++++
>  2 files changed, 11 insertions(+), 2 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/i915_pmu.c b/drivers/gpu/drm/i915/i915_pmu.c
> index 2b63ee31e1b3..725b01b00775 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);
>  }
> 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
>
diff mbox series

Patch

diff --git a/drivers/gpu/drm/i915/i915_pmu.c b/drivers/gpu/drm/i915/i915_pmu.c
index 2b63ee31e1b3..725b01b00775 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);
 }
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.
 	 */