AMDGPU LRU Bulk Move Patches Yielding OpenCL & Vulkan Performance Boosts

AMD's Huang Rui and Christian Konig are working on LRU bulk move functionality that can yield performance improvements for Vulkan and OpenCL workloads.

This AMDGPU kernel change is about migrating PD/PT buffer objects onto the LRU (least recently used) list in bulk in a single operation. For end-users, what matters is the performance difference as a result.

With this patch on an unidentified Radeon graphics card it boosts the Vulkan performance in Talos Principle from 147 FPS to 163 FPS while for OpenCL workloads is dropping the latency from 76 us to 40 us in one of the benchmarks. These numbers are even better than an earlier workaround patch by Christian that has yet to be mainlined in the Linux kernel.

The technical details on these five AMDGPU DRM kernel driver patches can be found via amd-gfx. It's too late for seeing it potentially in Linux 4.19 but hopefully we'll see this nice performance-boosting work queued for Linux 5.0.