| Summary: | [bisected] HD4000 performance regression in Epic Citadel (Unreal Engine WebGL demo) | ||
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| Product: | Mesa | Reporter: | Vedran Rodic <vrodic> |
| Component: | Drivers/DRI/i965 | Assignee: | Eric Anholt <eric> |
| Status: | RESOLVED FIXED | QA Contact: | |
| Severity: | normal | ||
| Priority: | medium | CC: | eric, kenneth |
| Version: | git | ||
| Hardware: | Other | ||
| OS: | All | ||
| Whiteboard: | |||
| i915 platform: | i915 features: | ||
| Attachments: |
fix epic citadel (unreal engine web gl demo)
better version of patch that shows the crux of the matter (as suggested by Alexander Monakov on #intel-gfx) |
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Description
Vedran Rodic
2013-05-04 12:50:47 UTC
Created attachment 78842 [details]
better version of patch that shows the crux of the matter (as suggested by Alexander Monakov on #intel-gfx)
Now that we're using Y-tiling, MapTextureImage can't use the BLT path, so it falls back to GTT mapping, which is really slow. It makes ReadPixels eat 65% of the CPU when it used to use hardly any. I see a couple of solutions to this: 1. Implement map/unmap via BLORP 2. Implement Y-tiling support for BLTs on Gen7+ 3. Only Y-tile compressed formats for now? #1 requires hooking into blorp at a lower level than is done currently, so it's non-trivial but looks doable. #2 means MI_LOAD_REGISTER_IMM'ing a register, with all the known issues there. #3 is easy, but I'd have to measure the performance cost. Eric, thoughts? Other ideas? Patch series on the list that gets things back to where they probably were before. Note that for actual decent performance you need to go to about:config and set"layers.acceleration.force-enabled". I've been chatting with the moz folks and they seem pretty open to whitelisting us pending a bit of perf testing, so hopefully this will get better soon. Confirmed fixed. layers.acceleration.force-enabled helps a lot 43.6 FPS compared to 18.9 before. And Y tiling definitely helps, I tried mesa git with X tiling forced (modified intel_mipmap_tree) just to test, and I got 41.8 FPS. Thanks |
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