A Meta developer's Linux patch could boost Steam Deck frame rates by up to 32%

Linux is Game: The Steam Deck was built around AMD APUs and the Linux-based SteamOS platform. APUs have to work within tight power constraints, which is why some developers are pushing the software side as far as it'll go to make games run faster.

David Vernet, a Linux kernel hacker at Meta, recently unveiled a series of new patches for the open source kernel. He explained that the code is designed to cut down on stuttering and frame-time spikes on AMD APU-based gaming handhelds, thanks to a new operating mode added to the amd-pstate driver.

Amd-pstate is a driver designed to improve control over processor frequency in AMD CPUs running a Linux-based operating system. The driver includes the Energy Performance Preference (EPP) attribute, which tells the hardware whether the currently running software wants maximum speed or wants to save battery power instead.

Vernet's patches build on active EPP mode, which normally lets the AMD APU decide the best strategy for whatever's running. He explained that gaming workloads, mostly built around one "busy" thread taking frequent short sleeps, tend to perform poorly under that kind of scheme.

The new code adds a per-core EPP boost. When the epp_boost module is enabled in Linux, each core on the processor is sampled every 10 ms. If a core is at least 50% busy, its EPP field is set to "performance," and it stays there until 300 ms pass without another busy sample, at which point the driver restores the core's previous EPP setting.

According to benchmark data Vernet provided, the new EPP boost mechanism can have a significant impact on frame rate, especially at the 1%-low level. He tested Civilization VI on a Steam Deck and found its 1%-low frame rate improved by 31.8%. The p99 frame time improved by 4.1%, though average frame rate was unaffected.

Vernet used Civ VI for his tests because of the game's heavy reliance on single-thread CPU performance, and because it offers a repeatable, built-in benchmark pass. Most likely he also just likes the game. Still, the proposed patches should theoretically benefit other games running on any SteamOS (or Linux) handheld with an AMD APU.