Re: [PATCH 10/19] drm/i915: Remove USES_GUC_SUBMISSION() pointer chasing from gen8_cs_irq_handler

[Tvrtko Ursulin <tvrtko.ursulin@linux.intel.com>]

On 17/05/2018 08:40, Chris Wilson wrote:
> Store whether or not we need to kick the guc's execlists emulation on
> the engine itself to avoid chasing the device info.

We do not chase device info but modparams in this case.

> gen8_cs_irq_handler                          512     428     -84

I guess my point from before, (unfortunately I forgot to reply), was how 
much of the saving remains if GEM_BUG_ON is compiled out?

If nothing or almost nothing, I don't see a need to fiddle with this now.

Regards,

Tvrtko

> 
> Signed-off-by: Chris Wilson <chris@chris-wilson.co.uk>
> ---
>   drivers/gpu/drm/i915/i915_irq.c             | 4 +++-
>   drivers/gpu/drm/i915/intel_guc_submission.c | 1 +
>   drivers/gpu/drm/i915/intel_lrc.c            | 1 +
>   drivers/gpu/drm/i915/intel_ringbuffer.h     | 7 +++++++
>   4 files changed, 12 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/i915/i915_irq.c b/drivers/gpu/drm/i915/i915_irq.c
> index f9bc3aaa90d0..460878572515 100644
> --- a/drivers/gpu/drm/i915/i915_irq.c
> +++ b/drivers/gpu/drm/i915/i915_irq.c
> @@ -1472,8 +1472,10 @@ gen8_cs_irq_handler(struct intel_engine_cs *engine, u32 iir)
>   	}
>   
>   	if (iir & GT_RENDER_USER_INTERRUPT) {
> +		if (intel_engine_uses_guc(engine))
> +			tasklet = true;
> +
>   		notify_ring(engine);
> -		tasklet |= USES_GUC_SUBMISSION(engine->i915);
>   	}
>   
>   	if (tasklet)
> diff --git a/drivers/gpu/drm/i915/intel_guc_submission.c b/drivers/gpu/drm/i915/intel_guc_submission.c
> index 133367a17863..d9fcd5db4ea4 100644
> --- a/drivers/gpu/drm/i915/intel_guc_submission.c
> +++ b/drivers/gpu/drm/i915/intel_guc_submission.c
> @@ -1312,6 +1312,7 @@ int intel_guc_submission_enable(struct intel_guc *guc)
>   		engine->unpark = guc_submission_unpark;
>   
>   		engine->flags &= ~I915_ENGINE_SUPPORTS_STATS;
> +		engine->flags |= I915_ENGINE_USES_GUC;
>   	}
>   
>   	return 0;
> diff --git a/drivers/gpu/drm/i915/intel_lrc.c b/drivers/gpu/drm/i915/intel_lrc.c
> index 857ab04452f0..4928e9ad7826 100644
> --- a/drivers/gpu/drm/i915/intel_lrc.c
> +++ b/drivers/gpu/drm/i915/intel_lrc.c
> @@ -2305,6 +2305,7 @@ static void execlists_set_default_submission(struct intel_engine_cs *engine)
>   	engine->park = NULL;
>   	engine->unpark = NULL;
>   
> +	engine->flags &= ~I915_ENGINE_USES_GUC;
>   	engine->flags |= I915_ENGINE_SUPPORTS_STATS;
>   	if (engine->i915->preempt_context)
>   		engine->flags |= I915_ENGINE_HAS_PREEMPTION;
> diff --git a/drivers/gpu/drm/i915/intel_ringbuffer.h b/drivers/gpu/drm/i915/intel_ringbuffer.h
> index acef385c4c80..4ad9c5842575 100644
> --- a/drivers/gpu/drm/i915/intel_ringbuffer.h
> +++ b/drivers/gpu/drm/i915/intel_ringbuffer.h
> @@ -574,6 +574,7 @@ struct intel_engine_cs {
>   #define I915_ENGINE_NEEDS_CMD_PARSER BIT(0)
>   #define I915_ENGINE_SUPPORTS_STATS   BIT(1)
>   #define I915_ENGINE_HAS_PREEMPTION   BIT(2)
> +#define I915_ENGINE_USES_GUC         BIT(3)
>   	unsigned int flags;
>   
>   	/*
> @@ -651,6 +652,12 @@ intel_engine_has_preemption(const struct intel_engine_cs *engine)
>   	return engine->flags & I915_ENGINE_HAS_PREEMPTION;
>   }
>   
> +static inline bool
> +intel_engine_uses_guc(const struct intel_engine_cs *engine)
> +{
> +	return engine->flags & I915_ENGINE_USES_GUC;
> +}
> +
>   static inline bool __execlists_need_preempt(int prio, int last)
>   {
>   	return prio > max(0, last);
> 
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