https://bugzilla.kernel.org/show_bug.cgi?id=218525 Bug ID: 218525 Summary: Thunderbolt eGPU bad performance Product: Drivers Version: 2.5 Hardware: All OS: Linux Status: NEW Severity: normal Priority: P3 Component: USB Assignee: drivers_usb@xxxxxxxxxxxxxxxxxxxxxx Reporter: gipawu@xxxxxxxxx Regression: No I opened this bug report because I think there is a performance problem in the Thunderbolt stack. I have an eGPU R43SG-TB3 adapter, which can be connected either via Thunderbolt 3/4 port, or directly via PCIe M.2 x4 link. Using the eGPU connected via Thunderbolt, game performance is often absymal, especially with games that use DXVK. The problem is described at length here: https://gitlab.freedesktop.org/drm/amd/-/issues/2885 but in summary, the main symptoms that indicate the presence of a performance problem with Thunderbolt eGPU are: - Low and bumpy fps, GPU clock speeds and GPU usage. - Low or no difference when downscaling the resolution or reducing graphic settings. Using the direct M.2 connection instead, performance is as good as expected, almost on the level of Windows. In Windows there is a performance gap of 5-10% between Thunderbolt and M.2 connection, but in Linux the gap is much wider, sometimes more than 50%. Very few games seem to be unaffected by the problem (e.g. Shadows of Tomb Raider and Doom Eternal). I tested with an Nvidia RTX 2060 Super GPU, paired with an Intel Nuc 13 Pro (i5-1340p and Thunderbolt 4) and with a Dell XPS 9570 (i7-8750H and Thunderbolt 3), both running Fedora 39 and kernel 6.7.5. I tried kernel 6.8.0 rc5 too, but with no differences. Since the problem emerges with both Nvidia and AMD GPUs (as evident from the linked report) and that the problem is not reproducible by connecting the GPU directly via M.2 connection, bypassing the Thunderbolt port, I suspect there is a performance issue in the Thunderbolt stack, perhaps in proper bandwidth allocation. I hope that information given here, and in the link given, may help to resolve the problem. I am of course available to provide additional information, logs, and test any patches if needed. Thank you. -- You may reply to this email to add a comment. You are receiving this mail because: You are watching the assignee of the bug.
