[Intel-gfx] [PATCH 04/12] drm/i915/execlists: Shortcircuit queue_prio() for no internal levels

[Mika Kuoppala]

Chris Wilson <chris at chris-wilson.co.uk> writes:

> If there are no internal levels and the user priority-shift is zero, we
> can help the compiler eliminate some dead code:
>
> Function                                     old     new   delta
> start_timeslice                              169     154     -15
> __execlists_submission_tasklet              4696    4659     -37
>
> Signed-off-by: Chris Wilson <chris at chris-wilson.co.uk>

Reviewed-by: Mika Kuoppala <mika.kuoppala at linux.intel.com>

> ---
>  drivers/gpu/drm/i915/gt/intel_lrc.c | 3 +++
>  1 file changed, 3 insertions(+)
>
> diff --git a/drivers/gpu/drm/i915/gt/intel_lrc.c b/drivers/gpu/drm/i915/gt/intel_lrc.c
> index de5be57ed6d2..3214a4ecc31a 100644
> --- a/drivers/gpu/drm/i915/gt/intel_lrc.c
> +++ b/drivers/gpu/drm/i915/gt/intel_lrc.c
> @@ -446,6 +446,9 @@ static int queue_prio(const struct intel_engine_execlists *execlists)
>  	 * we have to flip the index value to become priority.
>  	 */
>  	p = to_priolist(rb);
> +	if (!I915_USER_PRIORITY_SHIFT)
> +		return p->priority;
> +
>  	return ((p->priority + 1) << I915_USER_PRIORITY_SHIFT) - ffs(p->used);
>  }
>  
> -- 
> 2.20.1
>
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