Up to 11% perf drop in (all) onscreen GPU bound 3D benchmarks
Between following drm-tip commits:
- 2023-11-01 10:53:03 UTC: ac3eb5045c: drm-tip: 2023y-11m-01d-10h-52m-15s UTC integration manifest
- 2023-11-02 15:16:16 UTC: 76cfd6fff7: drm-tip: 2023y-11m-02d-15h-14m-32s UTC integration manifest
Performance in GPU bound onscreen 3D benchmarks dropped noticeably, and no benchmark improved.
BXT J4205 (HD Graphics 505) perf drops:
- 11% SynMark2 CSCloth
- 10% SynMark2 TexMem128 & Batch3
- 9% SynMark2 GSCloth, Batch2, Batch1, Batch0, GeomTriStrip, VSDiffuse8, GeomTriList, VSDiffuse1 and VSTangent
- 8% GfxBench5 Tess & ALU2, SynMark2 PSBum8, PSBump2, PSPhong, FillTexMulti and Deferred
- 7% SynMark2 PSPom, TexFilterTri and TexFilterAniso, GpuTest0.7 FurMark & PixMark Piano
- 6% GpuTest0.7 PixMark Volplosion, GiMark, JuliaFP64 and TessMark64, GpuMemBW TexelRate, Write, Blend, FLOPS and PixelRate
- 5% SyMark2 TerrrainPanInst & ShMapVsm
- 4% GfxBench5 Manhattan 3.1, CarChase and T-Rex, SynMark2 ZBuffer, TerrainPanTess, Batch4. GeomPoint, CSDof, GpuTest0.7 JuliaFP32
- 3-4% Unigine Heaven & Valley
- etc
Average power usage during the run of all benchmarks rose also several percents.
GLK results regress in similar way.
Setup / other notes:
- All tests run in fullscreen on FullHD display
- Regression is same with Mesa Git versions from few days ago, and few months ago
- Those GEN9 BXT (2MB L2) and GLK (4MB L2) run Ubuntu 22.04.3 LTS with distro Unity/Compiz/X as desktop
- GEN12 TGL (8MB LLC) using same Ubuntu 22.04.3 LTS setup with Unity/Compiz/X did not show regressions
- Another BXT, running ClearLinux with Weston, did not show regression either
- (no data from any other GPUs / machines)
Reason for differences between those BXT setups could be that:
- Ubuntu uses "powersave" scaling governor, ClearLinux "performance" one
- => Because perf drop happens only in onscreen cases, not in any of the offscreen ones, I don't think this to be a factor
- Weston/Wayland has proper modifier support, but AFAIK that is disabled in upstream & Ubuntu X server
- => Render buffer compression won't be used for onscreen X window buffers
=> regression could be specific either to older GENs, or iGPUs that do not have LLC, and handling of non-compressed screen buffers?