[Intel-gfx] [PATCH 25/38] drm/i915/pmu: Always sample an active ringbuffer

[Tvrtko Ursulin]

On 18/01/2019 14:00, Chris Wilson wrote:
> As we no longer have a precise indication of requests queued to an
> engine, make no presumptions and just sample the ring registers to see
> if the engine is busy.
> 
> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> ---
>   drivers/gpu/drm/i915/i915_pmu.c | 47 +++++++++++----------------------
>   1 file changed, 16 insertions(+), 31 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_pmu.c b/drivers/gpu/drm/i915/i915_pmu.c
> index b1cb2d3cae16..452589a7e473 100644
> --- a/drivers/gpu/drm/i915/i915_pmu.c
> +++ b/drivers/gpu/drm/i915/i915_pmu.c
> @@ -148,14 +148,6 @@ void i915_pmu_gt_unparked(struct drm_i915_private *i915)
>   	spin_unlock_irq(&i915->pmu.lock);
>   }
>   
> -static bool grab_forcewake(struct drm_i915_private *i915, bool fw)
> -{
> -	if (!fw)
> -		intel_uncore_forcewake_get(i915, FORCEWAKE_ALL);
> -
> -	return true;
> -}
> -
>   static void
>   add_sample(struct i915_pmu_sample *sample, u32 val)
>   {
> @@ -168,7 +160,6 @@ engines_sample(struct drm_i915_private *dev_priv, unsigned int period_ns)
>   	struct intel_engine_cs *engine;
>   	enum intel_engine_id id;
>   	intel_wakeref_t wakeref;
> -	bool fw = false;
>   
>   	if ((dev_priv->pmu.enable & ENGINE_SAMPLE_MASK) == 0)
>   		return;
> @@ -180,37 +171,31 @@ engines_sample(struct drm_i915_private *dev_priv, unsigned int period_ns)
>   	if (!wakeref)
>   		return;
>   
> +	intel_uncore_forcewake_get(dev_priv, FORCEWAKE_ALL);
>   	for_each_engine(engine, dev_priv, id) {
> -		u32 current_seqno = intel_engine_get_seqno(engine);
> -		u32 last_seqno = intel_engine_last_submit(engine);
> +		typeof(engine->pmu) *pmu = &engine->pmu;

Or name the struct?

>   		u32 val;
>   
> -		val = !i915_seqno_passed(current_seqno, last_seqno);
> -
> -		if (val)
> -			add_sample(&engine->pmu.sample[I915_SAMPLE_BUSY],
> -				   period_ns);
> +		val = I915_READ_FW(RING_MI_MODE(engine->mmio_base));
> +		if (val & MODE_IDLE)
> +			continue;
>   
> -		if (val && (engine->pmu.enable &
> -		    (BIT(I915_SAMPLE_WAIT) | BIT(I915_SAMPLE_SEMA)))) {
> -			fw = grab_forcewake(dev_priv, fw);
> +		add_sample(&pmu->sample[I915_SAMPLE_BUSY], period_ns);
>   
> +		if (pmu->enable &
> +		    (BIT(I915_SAMPLE_WAIT) | BIT(I915_SAMPLE_SEMA))) {
>   			val = I915_READ_FW(RING_CTL(engine->mmio_base));
> -		} else {
> -			val = 0;
> -		}
>   
> -		if (val & RING_WAIT)
> -			add_sample(&engine->pmu.sample[I915_SAMPLE_WAIT],
> -				   period_ns);
> +			if (val & RING_WAIT)
> +				add_sample(&pmu->sample[I915_SAMPLE_WAIT],
> +					   period_ns);
>   
> -		if (val & RING_WAIT_SEMAPHORE)
> -			add_sample(&engine->pmu.sample[I915_SAMPLE_SEMA],
> -				   period_ns);
> +			if (val & RING_WAIT_SEMAPHORE)
> +				add_sample(&pmu->sample[I915_SAMPLE_SEMA],
> +					   period_ns);
> +		}
>   	}
> -
> -	if (fw)
> -		intel_uncore_forcewake_put(dev_priv, FORCEWAKE_ALL);
> +	intel_uncore_forcewake_put(dev_priv, FORCEWAKE_ALL);
>   
>   	intel_runtime_pm_put(dev_priv, wakeref);
>   }
> 

Reviewed-by: Tvrtko Ursulin <tvrtko.ursulin at intel.com>

Regards,

Tvrtko