Steam Deck frame pacing improves with per-core AMD P-State boost
A proposed Linux update could improve gaming performance on the Steam Deck and other AMD systems. Early testing shows a 31.8% increase in 1% low FPS, which should result in fewer noticeable frame drops.
The patch adds a feature called epp_boost to the AMD P-State driver. It temporarily tells a busy CPU core to run in performance mode instead of waiting for the system to raise its clock speed.
“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.”
— David Vernet
Games often pause their main CPU thread for a very short time while waiting for the GPU. The current driver can treat these pauses as lower CPU usage and reduce clock speeds, even though the core becomes busy again almost immediately.
The results
In the Civilization VI benchmark, the main Steam Deck CPU core was running at a median clock of 2.43 GHz despite being 98% busy. With the patch enabled, the median clock increased to 3.5 GHz. The 99th-percentile frame time also improved by 4.1% , while average FPS stayed the same.
The boost only applies to recently busy CPU cores and turns off after 300 ms of lower activity. The patch is still under review and requires a modified kernel with amd_pstate.epp_boost=1 enabled.
In other words, should this patch reach the Linux kernel, gamers could see smoother gameplay in some scenarios without changing average FPS. The 1% low result represents the slowest frames during a benchmark, so a higher figure usually means fewer noticeable stutters and more consistent frame delivery.
Source: Phoronix
