[Intel-gfx] [PATCH] drm/i915: Show support for accurate sw PMU busyness tracking

[Tvrtko Ursulin]

On 03/07/2019 15:37, Chris Wilson wrote:
> Expose whether or not we support the PMU software tracking in our
> scheduler capabilities, so userspace can query at runtime.
> 
> v2: Use I915_SCHEDULER_CAP_ENGINE_BUSY_STATS for a less ambiguous
> capability name.
> 
> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>
> Cc: Tvrtko Ursulin <tvrtko.ursulin at intel.com>
> ---
> For reference, Tvrtko suggested an alternative back in Feb,
> "I am leaning towards thinking PMU is a backend and not the scheduler
> feature. We could export it via engine discovery for instance."
> -Chris
> ---
>   drivers/gpu/drm/i915/gt/intel_engine_cs.c | 7 ++++---
>   drivers/gpu/drm/i915/i915_pmu.c           | 4 +---
>   include/uapi/drm/i915_drm.h               | 1 +
>   3 files changed, 6 insertions(+), 6 deletions(-)
> 
> diff --git a/drivers/gpu/drm/i915/gt/intel_engine_cs.c b/drivers/gpu/drm/i915/gt/intel_engine_cs.c
> index c1fb5fa3952e..7d6d6e62e9cc 100644
> --- a/drivers/gpu/drm/i915/gt/intel_engine_cs.c
> +++ b/drivers/gpu/drm/i915/gt/intel_engine_cs.c
> @@ -688,9 +688,10 @@ void intel_engines_set_scheduler_caps(struct drm_i915_private *i915)
>   		u8 engine;
>   		u8 sched;
>   	} map[] = {
> -#define MAP(x, y) { ilog2(I915_ENGINE_HAS_##x), ilog2(I915_SCHEDULER_CAP_##y) }
> -		MAP(PREEMPTION, PREEMPTION),
> -		MAP(SEMAPHORES, SEMAPHORES),
> +#define MAP(x, y) { ilog2(I915_ENGINE_##x), ilog2(I915_SCHEDULER_CAP_##y) }
> +		MAP(HAS_PREEMPTION, PREEMPTION),
> +		MAP(HAS_SEMAPHORES, SEMAPHORES),
> +		MAP(SUPPORTS_STATS, ENGINE_BUSY_STATS),
>   #undef MAP
>   	};
>   	struct intel_engine_cs *engine;
> diff --git a/drivers/gpu/drm/i915/i915_pmu.c b/drivers/gpu/drm/i915/i915_pmu.c
> index 8fe46ee920a0..eff86483bec0 100644
> --- a/drivers/gpu/drm/i915/i915_pmu.c
> +++ b/drivers/gpu/drm/i915/i915_pmu.c
> @@ -102,10 +102,8 @@ static bool pmu_needs_timer(struct drm_i915_private *i915, bool gpu_active)
>   	/*
>   	 * Also there is software busyness tracking available we do not
>   	 * need the timer for I915_SAMPLE_BUSY counter.
> -	 *
> -	 * Use RCS as proxy for all engines.
>   	 */
> -	else if (intel_engine_supports_stats(i915->engine[RCS0]))
> +	else if (i915->caps.scheduler & I915_SCHEDULER_CAP_ENGINE_BUSY_STATS)
>   		enable &= ~BIT(I915_SAMPLE_BUSY);
>   
>   	/*
> diff --git a/include/uapi/drm/i915_drm.h b/include/uapi/drm/i915_drm.h
> index 328d05e77d9f..469dc512cca3 100644
> --- a/include/uapi/drm/i915_drm.h
> +++ b/include/uapi/drm/i915_drm.h
> @@ -521,6 +521,7 @@ typedef struct drm_i915_irq_wait {
>   #define   I915_SCHEDULER_CAP_PRIORITY	(1ul << 1)
>   #define   I915_SCHEDULER_CAP_PREEMPTION	(1ul << 2)
>   #define   I915_SCHEDULER_CAP_SEMAPHORES	(1ul << 3)
> +#define   I915_SCHEDULER_CAP_ENGINE_BUSY_STATS	(1ul << 4)
>   
>   #define I915_PARAM_HUC_STATUS		 42
>   
> 

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

Regards,

Tvrtko