Linux 6.6 Delivers Some Impressive Gains For AMD EPYC 9754 "Bergamo" Server Performance

From my early testing thus far of the Linux 6.6 kernel in its very early state, some of the most impressive gains are happening on AMD's high core count server processors, the EPYC 9754 "Bergamo" in particular is enjoying some stellar improvements for various server workloads on this forthcoming kernel.

Following the release of Linux 6.6-rc1, now that the merge window is over like usual it's a matter of beginning to test the new kernel code on a range of hardware. With the new Linux 6.6 kernel features it's very interesting for the EEVDF scheduler. The Earliest Eligible Virtual Deadline First scheduler is a virtual-time scheduler that originates from a late 90's research paper. EEVDF is a major rework to the kernel's scheduler code and a major improvement over the existing Completely Fair Scheduler (CFS). Peter Zijlstra of Intel led the development of the EEVDF code that is mainlined for the first time with Linux 6.6. Public benchmarks of EEVDF have been slim thus far but has shown to help with latency sensitive tasks. In turn it already led to a lot of CFS code being removed. Another optimization benefiting AMD CPUs and other chiplet-based CPUs with multiple L3 caches are the Linux 6.6 workqueue improvements.

In my testing the past few days of Linux 6.6 post-RC1 there have been some wins on desktop class AMD/Intel processors (those benchmarks coming soon on Phoronix) but some of the most dramatic improvements have been with higher core count processors, in particularly focusing a lot of testing this week using an AMD EPYC 9754 1P server configuration given its 128 cores / 256 threads per socket. Benchmarks on other high core count AMD and Intel server processors will come on Phoronix over the next week or two while for now are the initial results when stressing the AMD EPYC 9754 Bergamo server platform.

With the same hardware benchmarks were carried out using Linux 6.5.1 stable and then running with Linux 6.6-rc1 that was released on Sunday. For easy reproducibility the kernel builds were obtained from the Ubuntu Mainline Kernel PPA. No other changes were made besides swapping out the tested Linux kernel build on this AMD EPYC 9754 server.