SteamOS 3.8.20 beta brings smarter VRAM management for AMD GPUs

The latest SteamOS beta, version 3.8.20, includes a significant memory management improvement aimed at AMD GPUs with limited VRAM — the kind found in every SteamOS device on the market. The fix comes from independent contractor Natalie Vock, who works on RADV, the open-source community Vulkan driver for AMD GPUs.

The core problem was how Linux handled VRAM allocation when a game's data exceeded the GPU's dedicated memory pool. When VRAM fills up, the OS spills overflow into the GTT — a secondary pool inside system memory that the GPU accesses over the PCIe interface. PCIe has far less bandwidth and worse latency than dedicated VRAM, so any data the GPU needs that lives in GTT causes a performance hit. Worse, the OS had no reliable way to know which data was critical, and the constant shuffling between memory pools caused stalls. The previous allocation strategy told the kernel to treat GTT as an acceptable fallback rather than a last resort, meaning Linux wasn't aggressive enough about keeping game data in VRAM. Vock demonstrated this with Cyberpunk 2077 on an 8 GB GPU: the game was only using 6,105 MB of VRAM, yet Linux had already pushed 1,370 MB into GTT unnecessarily.

The fix uses Linux kernel cgroups — control groups that let the OS enforce fine-grained rules over how resources are allocated and protected per process. What was missing was a dedicated VRAM cgroup controller. Vock, alongside Maarten Lankhorst from Intel and Maxime Ripard from Red Hat Linux, developed the kernel patch, assisted by a tool called dmemcg-booster. Together these changes let SteamOS actively protect a game's VRAM allocation and prevent the OS from evicting critical data prematurely. Devices with integrated GPUs, however, are unlikely to benefit — iGPUs share system memory rather than having a discrete VRAM pool, so the underlying problem doesn't apply in the same way.

The improvement is currently live in the 3.8.20 beta channel. Players with VRAM-constrained handhelds or mini-PCs running SteamOS — particularly those pushing demanding titles that sit close to the VRAM ceiling — are the most likely to notice the gains once the update reaches stable.