Last week I published an article looking at [1]the power efficiency of 5th Gen AMD EPYC "Turin" using the modern AMD P-State driver and the Power Profile options . The AMD P-State driver being used by default now for the EPYC 9005 series processors on Linux 6.12+ and paired with Power Profile option tuning can deliver a nice boost to server energy efficiency with only modest impact to the performance. Today's article are some complementary numbers I carried out recently on a Supermicro server looking at more of the Power Profile Selection options.

[2]

Today's testing is a look at the Power Profile Selection tunables available on a retail Supermicro EPYC 9004/9005 series motherboard: the [3]Supermicro H13SSL-N . This motherboard unfortunately though with the current BIOS lacks ACPI CPPC support and thus is unable to run with the AMD P-State driver even when using the newest versions of the Linux kernel. Thus the generic ACPI CPUFreq driver that's long been the default for EPYC processors is still used. So keep that in mind that it's less optimal for EPYC 9005 but nevertheless an interesting set of data points for those running on servers without ACPI CPPC support and/or relying on older enterprise Linux kernels where amd_pstate may not be available or in less ideal form if overriding it to be enabled for the EPYC 9005 processors.

[4]

These benchmarks were done on the Linux 6.12 kernel that was the newest at the time when I initiated these benchmarks on the AMD EPYC 9655 with the Supermicro H13SSL-N. The tested Power Profile Selection configurations paired with different ACPI CPUFreq governor options included:

- Balanced Core Memory Perf - acpi-cpufreq performance

- Balanced Core Memory Perf - acpi-cpufreq schedutil

- Balanced Core Perf - acpi-cpufreq performance

- Balanced Core Perf - acpi-cpufreq schedutil

- Balanced Memory Perf - acpi-cpufreq performance

- Balanced Memory Perf - acpi-cpufreq schedutil

- Default - High Perf - acpi-cpufreq performance

- Default - High Perf - acpi-cpufreq schedutil

- Efficiency Mode - acpi-cpufreq performance

- Efficiency Mode - acpi-cpufreq schedutil

- Maximum IO Perf - acpi-cpufreq performance

- Maximum IO Perf - acpi-cpufreq schedutil

[5]

The default Power Profile Selection is the "High Performance Mode". For pre-6.12 kernels or platforms without ACPI CPPC, ACPI CPUFreq is the default CPU frequency scaling driver. Depending upon the Linux distribution or kernel modifications, the governor will either be the "performance" governor or the "schedutil" governor that makes use of scheduler utilization data. ACPI CPUFreq Schedutil is the default behavior on Ubuntu Linux.

Beyond looking at the impact to performance for each of these modes, the AC system power consumption (total "wall power"), CPU power consumption, CPU thermals, and CPU peak frequency were also recorded for each of these modes.

Again, these numbers are mainly being put out for reference purposes for those wondering about the impact of the Power Profile Selection either from the system BIOS or AMD HSMP utility for adjusting and this round was with the acpi-cpufreq driver.



[1] https://www.phoronix.com/review/amd-epyc-pstate-efficiency

[2] https://www.phoronix.com/image-viewer.php?id=amd-power-profile-linux&image=power_profile_selection_0_lrg

[3] https://www.phoronix.com/review/supermicro-h13ssln-epyc-turin

[4] https://www.phoronix.com/image-viewer.php?id=amd-power-profile-linux&image=power_profile_selection_1_lrg

[5] https://www.phoronix.com/image-viewer.php?id=amd-power-profile-linux&image=power_profile_selection_2_lrg