INFRA Signal 397
Linux 7.2 To Revert Back To The FIFO DRM Scheduler Policy Due To "Fair" Regressions
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Linux kernel version 7.2 will switch the DRM scheduler default back to FIFO after the newer fair scheduler caused regressions.
The DRM scheduler controls how graphics commands are ordered for GPU execution, so a regression can impact performance or stability of graphics drivers such as AMDGPU. Restoring the FIFO policy avoids those regressions and preserves the expected behavior for existing driver stacks.
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Linux 7.2 originally changed the DRM scheduler default from FIFO to a fair policy.
The fair scheduler was intended to improve fairness for AMDGPU and other DRM drivers.
Observed regressions have led to a decision to revert the default back to FIFO.
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In the 7.2 kernel release the Direct Rendering Manager (DRM) subsystem switched its default scheduling algorithm from the long-standing FIFO policy to a new "fair" scheduler. The change was marketed as a way to provide more equitable GPU command handling, and it was applied to drivers such as AMDGPU and other DRM graphics drivers.
Subsequent testing or deployment revealed regressions attributed to the fair scheduler, prompting maintainers to consider the impact on overall system performance and stability. The exact nature of the regressions is not detailed, but the decision to roll back indicates they were significant enough to outweigh the intended fairness benefits.
Reverting to FIFO means the kernel will once again use the simple first-in-first-out ordering as the default for DRM command queues. For most engineers this requires no code changes; the default behavior is restored automatically when upgrading to 7.2, and existing driver code continues to operate as before.
The fair scheduler remains in the source tree and can still be selected manually, but it will no longer be the out-of-the-box choice. Workloads that explicitly depend on the fair policy will need to enable it via configuration or patching, and they should verify that the earlier regressions do not affect their use case.
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