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

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@intel.com>
Signed-off-by: Zhenyu Wang <zhenyuw@linux.intel.com>
hifive-unleashed-5.1
Changbin Du 2017-04-06 10:55:55 +08:00 committed by Zhenyu Wang
parent 80901ca879
commit 43c29e1f44
1 changed files with 0 additions and 6 deletions
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6
drivers/gpu/drm/i915/gvt/cmd_parser.c
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@ -616,9 +616,6 @@ static inline u32 get_opcode(u32 cmd, int ring_id)
{
struct decode_info *d_info;
if (ring_id >= I915_NUM_ENGINES)
return INVALID_OP;
d_info = ring_decode_info[ring_id][CMD_TYPE(cmd)];
if (d_info == NULL)
return INVALID_OP;
@ -661,9 +658,6 @@ static inline void print_opcode(u32 cmd, int ring_id)
struct decode_info *d_info;
int i;
if (ring_id >= I915_NUM_ENGINES)
return;
d_info = ring_decode_info[ring_id][CMD_TYPE(cmd)];
if (d_info == NULL)
return;