Nearly 10% performance drop in SynMark CSCloth from "i965: Emit CS stall before MEDIA_VFE_STATE"
Submitted by Eero Tamminen
Assigned to Kenneth Graunke
Following commit drops performance in SynMark CSCloth test, as expected:
i965: Emit CS stall before MEDIA_VFE_STATE. This fixes hangs on GFXBench 5's Aztec Ruins benchmark. Unfortunately, it regresses OglCSCloth performance by about 10%. There are some ideas for fixing that. The Vulkan driver already emits this stall. Reviewed-by: Matt Turner <email@example.com>
The drop is:
- 8-9% on SKL GT4e
- 5-6% on KBL GT3e
- 3-4% on SKL & KBL GT2
- within (largish) variance on BDW GT2 & GT3
On HSW GT it would seem to actually improve perf marginally.
Latter is interesting because Kenneth's trial fix for the performance regression (verified to fix it): https://cgit.freedesktop.org/~kwg/mesa/commit/?h=vfe-stall-3&id=ab9bff0ac43f0d878106ba124e84edca9b359c8a
Is according to Kenneth causing problems on HSW. Maybe it could be applied only on newer GENs?