Linux 6.5+ Bringing Some Performance/Efficiency Improvements For The AMD Ryzen Z1 Extreme / ASUS ROG Ally

[phoronix]

Phoronix: Linux 6.5+ Bringing Some Performance/Efficiency Improvements For The AMD Ryzen Z1 Extreme / ASUS ROG Ally

With the recently released Linux 6.5 kernel bringing AMD P-State EPP by default for modern Ryzen systems rather than the generic ACPI CPUFreq driver, running Linux 6.5 (or newer) in various workloads can lead to improved performance and/or power efficiency. Curious about the impact on the mobile side, I recently carried out some benchmarks of the ASUS ROG Ally gaming handheld with AMD Ryzen Z1 Extreme SoC from Linux 6.3, 6.4, 6.5, and 6.6 Git kernels.

https://www.phoronix.com/review/ryzen-z1-linux65

[aviallon]

Thank you very much for the benchmarks Michael.
I was wondering, does the Linux 6.6 git already include EEVDS scheduler, or is not merged yet?

[Kjell]

I tried it out a couple of weeks ago and got to this conclusion with my Ryzen 9 5950X after enabling CPPC in BIOS, using CPUfreq governor "performance" and passing kernel flag:

• (Default) acpi-cpufreq, boosts to 4.8 GHz while gaming
• amd_pstate=active, [EEP], same as previous
• amd_pstate=passive, boosts to 5.1GHz
• amd_pstate=guided, same as previous

Here's some interesting benchmarks:

• https://lwn.net/ml/linux-kernel/[email protected]/
• https://lore.kernel.org/lkml/[email protected]/

Also, really looking forward to this performance update

• https://www.phoronix.com/news/AMD-Preferred-Core-Linux-v5

I believe amd_pstate is able to idle at a lower frequency as well, haven't tested it yet.

[Ranguvar]

Thank you very much for the benchmarks Michael.
I was wondering, does the Linux 6.6 git already include EEVDS scheduler, or is not merged yet?

As of end of Sep 2, Linus's master had EEVDF, yes.

From René's mail on LKML, it seems the new scheduler may provide closer to 10% boost in some workloads, while preferred core may not be as beneficial.

Unfortunately cppc feature flag does not appear to be exposed for at least desktop non-APU Zen3; see `lscpu` regardless of BIOS setting.
I tried amd_pstate on my 5950X, and found because of this, I needed both amd_pstate.shared_mem=1 and amd_pstate=active in the kernel command line before `cpupower frequency-info` would show the amd_pstate driver.
There were notes about shared_mem performance issues in Linux 6.0 docs, but those were removed in subsequent versions.

I don't have any benchmarks, though.
Frequency lows were 550MHz reported instead 2.2GHz, and peaks were similar, perhaps slightly higher.

Of course, this all depends on the benchmark, and lightly threaded web browsing or gaming loads are some of the most variable with scheduling and frequency behavior tweaks.