Linux 7.4 Gains AMD PerfOpt, a Speed Boost for Radeon Integrated Graphics

As expected, the AMD PerfOpt feature has been accepted into the Linux 7.4 kernel. The change targets systems with Radeon integrated graphics. Several Phoronix benchmarks show it delivers a solid performance gain, particularly in AI workloads.

How it works

PerfOpt allows the integrated GPU to bypass the IOMMU when directly accessing system memory. On systems with Radeon integrated graphics it is enabled by default and works through the AMDGPU kernel graphics driver. Users do not need to configure anything.

Phoronix founder Michael Larabel has already measured its impact in dedicated tests. In AI and large language model workloads, Radeon iGPUs gained as much as 18–23%. Prior-generation Ryzen APUs benefit as well.

To confirm the feature is active, check the kernel's dmesg output. On Linux 7.4 and newer, search for the string "PerfOpt": it indicates that the AMDGPU driver has armed the optimization.

What else came with the IOMMU update

PerfOpt landed as part of a larger set of changes to the IOMMU subsystem. Besides PerfOpt, that set includes:

• a number of fixes and clean-ups in the AMD IOMMU code;
• IOMMU support for the Broadcom BCM2712, needed by the Raspberry Pi 5's display and multimedia devices;
• a new para-virtualized IOMMU driver for Hyper-V, contributed by Microsoft.

Source: Phoronix