Re: [Intel-gfx] [PATCH] drm/i915: Simplify vcs/bsc engine selection

["Das, Nirmoy" <nirmoy.das@linux.intel.com>]

On 3/16/2023 3:27 PM, Tvrtko Ursulin wrote:
> From: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
>
> No need to look at the mask of present engines when we already have a
> count stored ever since e2d0ff3525b9 ("drm/i915: Count engine instances
> per uabi class").
>
> Signed-off-by: Tvrtko Ursulin <tvrtko.ursulin@intel.com>
> Cc: Jonathan Cavitt <jonathan.cavitt@intel.com>


Reviewed-by: Nirmoy Das <nirmoy.das@intel.com>

> ---
>   drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c | 10 +++-------
>   1 file changed, 3 insertions(+), 7 deletions(-)
>
> diff --git a/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c b/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
> index 9dce2957b4e5..3aeede6aee4d 100644
> --- a/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
> +++ b/drivers/gpu/drm/i915/gem/i915_gem_execbuffer.c
> @@ -2449,11 +2449,6 @@ static int eb_submit(struct i915_execbuffer *eb)
>   	return err;
>   }
>   
> -static int num_vcs_engines(struct drm_i915_private *i915)
> -{
> -	return hweight_long(VDBOX_MASK(to_gt(i915)));
> -}
> -
>   /*
>    * Find one BSD ring to dispatch the corresponding BSD command.
>    * The engine index is returned.
> @@ -2467,7 +2462,7 @@ gen8_dispatch_bsd_engine(struct drm_i915_private *dev_priv,
>   	/* Check whether the file_priv has already selected one ring. */
>   	if ((int)file_priv->bsd_engine < 0)
>   		file_priv->bsd_engine =
> -			get_random_u32_below(num_vcs_engines(dev_priv));
> +			get_random_u32_below(dev_priv->engine_uabi_class_count[I915_ENGINE_CLASS_VIDEO]);
>   
>   	return file_priv->bsd_engine;
>   }
> @@ -2655,7 +2650,8 @@ eb_select_legacy_ring(struct i915_execbuffer *eb)
>   		return -1;
>   	}
>   
> -	if (user_ring_id == I915_EXEC_BSD && num_vcs_engines(i915) > 1) {
> +	if (user_ring_id == I915_EXEC_BSD &&
> +	    i915->engine_uabi_class_count[I915_ENGINE_CLASS_VIDEO] > 1) {
>   		unsigned int bsd_idx = args->flags & I915_EXEC_BSD_MASK;
>   
>   		if (bsd_idx == I915_EXEC_BSD_DEFAULT) {