New Linux Kernel Patch Expected to Significantly Reduce Stutters on Steam Deck

The update still needs to be reviewed by AMD engineers.

An interesting improvement is being prepared for Steam Deck users and other Linux-based gaming devices powered by AMD processors. Linux kernel developer David Vernet has proposed a patch that can significantly reduce micro-stutters and improve gameplay smoothness without sacrificing average performance.

The problem is related to the operation of the AMD P-State driver in Energy Performance Preference (EPP) mode. During gaming, the main CPU thread periodically pauses briefly, waiting for the GPU to complete its work. The existing algorithm can mistakenly perceive such a pause as a reduction in load and prematurely decrease the core clock speed. When the thread reactivates, the processor operates at an insufficient frequency, leading to increased frame times and noticeable stutters.

A full transition of the processor to maximum performance mode eliminates the problem but negatively affects power consumption. For portable devices like the Steam Deck, this is especially important, as the CPU and GPU share a common power budget. Constantly increasing the minimum frequency also proved ineffective, as it disrupts the balance of power distribution between the central and graphics processors.

As a solution, Vernet proposed the epp_boost mechanism. Instead of changing system-wide settings, the patch analyzes the load on each CPU core every 10 milliseconds. If a specific core is at least 50% busy, it is temporarily switched to maximum performance mode. When the load decreases and remains low for 300 milliseconds, the core automatically returns to its usual power-saving policy.

Initial tests on the Steam Deck showed a noticeable effect. In the Civilization VI performance test, the 1% Low FPS increased by 31.8%, and the 99th percentile frame time improved by 4.1%. At the same time, the average frame rate remained unchanged.

Tests also showed that without the new mechanism, the most loaded CPU core, at 98% utilization, operated at a median frequency of about 2.43 GHz. After activating epp_boost, this figure increased to 3.5 GHz, allowing for faster responses to changes in gaming load.

Currently, the proposed patch has not yet been reviewed by AMD engineers responsible for Linux kernel support and has not yet been included in any official kernel version.