Hey,
Den 2025-08-29 kl. 12:55, skrev Thomas Hellström:
On Fri, 2025-08-29 at 09:42 +0200, Maarten Lankhorst wrote:
Hey,
Den 2025-08-28 kl. 17:42, skrev Thomas Hellström:
VRAM+TT bos that are evicted from VRAM to TT may remain in TT also after a revalidation following eviction or suspend.
This manifests itself as applications becoming sluggish after buffer objects get evicted or after a resume from suspend or hibernation.
If the bo supports placement in both VRAM and TT, and we are on DGFX, mark the TT placement as fallback. This means that it is tried only after VRAM + eviction.
This flaw has probably been present since the xe module was upstreamed but use a Fixes: commit below where backporting is likely to be simple. For earlier versions we need to open- code the fallback algorithm in the driver.
Closes: https://gitlab.freedesktop.org/drm/xe/kernel/-/issues/5995 Fixes: a78a8da51b36 ("drm/ttm: replace busy placement with flags v6")
I'd say it this closes a bug in the original driver, although effectively v6.8 is no longer supported anyway.
Should DESIRED also be set on the add_vram flags?
It looks for me from the TTM code that TTM then *skips* the placement when doing a second pass with evictions.
So that's not really what we want IMO. Yeah, seems the flag name is a bit misleading, it's more of an opportunistic placement
when space is available.
Kind regards, ~Maarten Lankhorst