Upgrading Linux 5.15 LTS To Linux 6.1 Can Yield Additional Performance For AMD EPYC "Milan" Servers
Released on Sunday was Linux 6.1 and in addition to having many new features making it all the more exciting is that it's expected to be this year's Long-Term Support (LTS) kernel release. As such it will see widespread adoption particularly among servers and much interest from the hyperscalers. For those weighing an upgrade from last year's Linux 5.15 LTS kernel, Linux 6.1 with initial testing on an AMD EPYC Milan-X 2P server has shown a nice speed bump is possible across a wide-range of workloads.
Linux 5.15 is the Long Term Support kernel of 2021. Linux 5.15 is expected to be maintained for at least another year through October 2023, but could be extended to six years or more like Linux 5.10, 5.4, 4.19, etc. Whether Linux 5.15 LTS is extended past October 2023 all comes down to usage and commitments from organizations planning to use the kernel in production deployments. With time we'll see similarly whether Linux 6.1 LTS is maintained for just two years or ends up being for 6+ years. Greg Kroah-Hartman typically picks the last kernel series of each calendar year to serve as that year's LTS version.
Given that many enterprises stick to the Linux LTS kernel versions, I ran some benchmarks on an AMD EPYC 7773X 2P server for seeing the performance differences across the past several Long Term Support series. Tested for today's comparison is the LTS branches of Linux 5.4 (5.4.224), Linux 5.10 (5.10.130), Linux 5.15 (5.15.81), and Linux 6.1 (Git snapshot from this past weekend).
These kernels were obtained from the Ubuntu Mainline Kernel PPA for easy reproducing and tested on the same server, which was a dual AMD EPYC 7773X (Milan-X) configuration with AMD's Daytona reference platform, 512GB of RAM, and 800GB Intel Optane P5800X (SSDPF21Q800GB) NVMe solid-state drive. The tests and hardware were kept the same and the only change being swapping out the Linux kernel in use.
A similar Linux LTS kernel comparison on Xeon Scalable "Ice Lake" hardware will be coming up in its own article shortly on Phoronix with this being a look at the AMD Milan(X) side. Milan-X was used rather than the latest AMD EPYC 9004 "Genoa" processors in order to maintain hardware support going back to the Linux 5.4 kernel release from late 2019.