https://bugs.freedesktop.org/show_bug.cgi?id=101946
--- Comment #14 from Robin beanow@oscp.info --- Created attachment 133108 --> https://bugs.freedesktop.org/attachment.cgi?id=133108&action=edit case3.sh
So, tinkering with the test script I've only been able to eliminate some suspicions and invalidate my observation the patch performed better.
I've taken out vfio-pci binding from the loop. It's only used during boot to keep the GPU free to unbind. So it's not related to vfio-pci's having access in between binds.
I've made 3 methods for rebinding amdgpu. amdgpu rmmod > modprobe remove pci devices > rescan driver unbind > bind
I've run each of these a few dozen times on each kernel and none of them really stand out. All of them have a chance to work (as in, ring 1 test failure only) or to fail.
4.13rc2, drm-next-4.14-wip, drm-next-4.14-wip + patch3 all have this behaviour. So no I don't think they've helped after all.