Introduction
Hello everyone,
The Ubuntu Kernel Team would like to acknowledge a performance regression identified within the amdgpu driver for the upcoming 7.0.0-28.28 kernel release. We want to thank our community testers and early adopters for identifying and reporting this behavior.
What to Expect
Affected users may experience a significant performance regression, particularly when running compute-heavy workloads that utilize ROCm, such as Stable Diffusion XL (SDXL) inference via ComfyUI. This manifests as a drastic increase in processing time—reports indicate slowdowns of up to 42× (e.g., from 9 seconds to 388 seconds). Please note that this is a throughput degradation rather than a system lockup.
Who is Affected
This is a targeted regression primarily affecting Ubuntu 26.04 users as well as users on the Hardware Enablement (HWE) stack for Ubuntu 24.04, who are currently scheduled to be migrated from the 6.17 to the 7.0 kernel. While the scope is still being refined, we have confirmed reports of this behavior on AMDGPU-based systems utilizing ROCm, specifically impacting compute-heavy workloads like Stable Diffusion XL (SDXL).
Roadmap
The Ubuntu Kernel Team is currently prioritizing the release of critical security fixes contained in the upcoming kernel release to ensure the safety of our users. While this specific regression will be present in the 7.0.0-28.28 release, we have already identified the resolution.
The fix is queued to be applied to the very next immediate batch of updates containing critical fixes. This approach allows us to balance the urgent need for security patches with the requirement for long-term performance stability.
Mitigation
In order to mitigate the performance regression, affected users are recommended to stay in their current kernel version until a kernel update is released with the proper fix. If your Ubuntu 26.04 system received a kernel update to version 7.0.0-28 and you are experiencing this issue, please reboot your system and choose the previous known good kernel version on the grub menu (please check this post for more information on how to do it).
References
For those interested in the technical background or following the upstream discussions, please refer to the following:
- ROCm Issue Tracker: AMDGPU Performance Regression
- ComfyUI Issue Tracker: Performance Regression on AMD Hardware
Updates
- July 22, 2026: The fix commit has been included in the latest Ubuntu 26.04 kernel build (version 7.0.0-29.29), available for early tests on Canonical Kernel Team “proposed (#2) PPA”. This kernel update is currently scheduled to be released during the week of August 2, 2026.
