https://bugs.freedesktop.org/show_bug.cgi?id=92775
--- Comment #2 from david1.zhou@amd.com david1.zhou@amd.com --- (In reply to Michel Dänzer from comment #1)
(In reply to Shawn Starr from comment #0)
One solution discussed is to split up the transfer into smaller chunks in radeon_ttm.
Specifically, here's how I think a fallback could be implemented in the kernel driver which can never fail because of fragmentation or resource starvation:
During initialization, reserve some pinned GTT memory for bounce buffers. When a BO can't be bound to GTT for eviction as in the case reported here, instead do the eviction directly from VRAM to CPU domain in one or several passes of:
- Copy part of the BO from VRAM to one of the reserved bounce buffers in
GTT using the GPU. 2. Copy that part of the BO from the bounce buffer to the BO's system RAM pages using the CPU.
if we can split a large BO to two parts, one is in VRAM, one is in GTT, seems also to be helpful for this case.