A set of patches recently posted to the Linux kernel mailing list seems to improve the 1% low framerate performance, specifically on the Steam Deck. The patches basically implement new per-core Energy Performance Preference (EPP) boosting for recently-busy CPUs.
For Linux Gaming, this would technically translate to an improvement of 31.8% on the 1% lows for the Steam Deck. We say technically because, at current, there is no implementation planned or being rolled out for the gaming handheld.
David Vernet, a Linux kernel hacker at Meta and, from the looks of it, the one who improved the AMD P-State driver with the aforementioned feature. “In active (EPP) mode the platform autonomously picks the operating point between min_perf and max_perf, biased by the EPP hint, and the kernel only rewrites the CPPC request on policy or limit changes. A workload dominated by one mostly-busy thread that takes frequent short sleeps (common in gaming workloads, for example) can fare poorly under this strategy. Each sleep decays the hardware’s performance signal, causing post-wakeup bursts to start at a low operating point and inflating tail latency even though the CPU is essentially fully busy while work is available.”
Their explanation is long and undoubtedly complicated. To condense it: games often pause their main CPU threading while waiting for the GPU, which then reduces the clock speeds, lowering CPU usage and thus conserving power. With this new kernel, it tells the CPU to operate in a sustained performance mode.
Again, it’s not been implemented on the Steam Deck, but early results show promise. Phoronix reports that in Civilization VI benchmarks, the Steam Deck’s main CPU core running at 3.5GHz with the patch. In addition to the 1% low being improved, the patch also improved 99th percentile frame time by approximately 4.1% while average FPS stay the same.
(Source: Phoronix)
