Linux 6.11-rc7 To Fix A "Massive Performance Regression" For AMD Graphics

Sent out today were the DRM fixes for 6.11-rc7 ahead of the Linux 6.11-rc7 kernel being released on Sunday. As usual most of the changes revolve around the AMDGPU and Intel i915/Xe drivers plus random fixes to the smaller drivers. There is one change though with the AMD Radeon graphics driver side worth highlighting to address a performance regression affecting recent kernels.

Notable from the AMDGPU fixes for this week is a fix to address CPU spikes when clearing VRAM. AMD's Alex Deucher authored a change to always allocate cleared VRAM for GEM allocations. Alex explained in the patch:

"This adds allocation latency, but aligns better with user expectations. The latency should improve with the drm buddy clearing patches that Arun has been working on.

In addition this fixes the high CPU spikes seen when doing wipe on release."

Notable is that it fixes this bug report: Massive performance regression in Dota 2 (maybe others) on Linux 6.10.2 compared to Linux-LTS 6.6.42. A user had found the performance within Valve's Dota 2 game and other titles like Rise of the Tomb Raider to regress substantially when moving to recent versions of the Linux kernel.

It turns out the regression was introduced four months ago when adding clear page functionality to the AMDGPU driver.

This regression didn't affect all games but for titles like Dota 2 ended up leading to a big performance loss:

This week's DRM fixes with this AMDGPU patch and the other fixes should be merged today to Linux Git and be found in Sunday's Linux 6.11-rc7 kernel release. In turn this patch should also be back-ported to current stable kernels.