Linux 6.5 now defaults to the AMD P-State EPP driver for Zen 2 and newer Ryzen systems, as long as the system supports ACPI CPPC. However, the AMD EPYC server processors still continue to use ACPI CPUFreq by default. Given the increasing interest in the AMD Ryzen 7000 series for budget and small-to-medium-sized business (SMB) servers, the performance impact of Linux 6.5 with more server workloads was analyzed.
Phoronix has tested the changes, and testing was conducted comparing the performance of Linux 6.4 against Linux 6.5, both out-of-the-box and using the Ubuntu Mainline Kernel PPA for easy reproducibility. The default change involves going from ACPI CPUFreq Schedutil to AMD P-State EPP with the
powersave governor. Additional tests were done with the
performance governor for maximum performance. AMD P-State is available on earlier Linux kernel versions but is not set to be used out-of-the-box until Linux 6.5 and later. The testing was done using the ASRock Rack 1U4LW-B650/2L2T, a 1U Ryzen AM5 server platform that supports Ryzen 7000 series processors and ECC memory. No other changes were made to the server during testing, except for swapping out the Linux kernel and running secondary tests with the performance governor. The CPU clock frequency differences in the automated system table were minimal and did not affect the testing results.
The article provides valuable insights for those interested in using Ryzen processors for server applications.