[PATCH] drm/i915/gvt: remove redundant ring id check which cause significant CPU misprediction

Zhenyu Wang zhenyuw at linux.intel.com
Wed Apr 12 06:00:16 UTC 2017


On 2017.04.06 10:55:55 +0800, changbin.du at intel.com wrote:
> From: Changbin Du <changbin.du at intel.com>
> 
> From perf data, found a significant overhead at ring id check in the
> function get_opcode. This inline function is frequently used.
> 
> Since Intel static predictor will predict the branch to fall through
> so the prediction most fail. This is wasting CPU pipeline resource.
> We do not need check the engine id everywhere, it should be reliable.
> 
> Signed-off-by: Changbin Du <changbin.du at intel.com>
> ---

applied, thanks!

-- 
Open Source Technology Center, Intel ltd.

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