I have a private libdrm amdgpu test which allocates very big BOs in loop
until all VRAM, GTT and swap are full, and I don't release them in the
test (yet) .
Once the test process terminates everything always gets cleared
including swap . Could this point to KFD specific issue ?
Thanks,
Andrey
On 01/16/2018 10:21 PM, Felix Kuehling wrote:
> I'm running an eviction stress test with KFD and find that sometimes it
> starts swapping. When that happens, swap usage goes up rapidly, but it
> never comes down. Even after the processes terminate, and all VRAM and
> GTT allocations are freed (checked in
> /sys/kernel/debug/dri/0/amdgpu_{gtt|vram}_mm), swap space is still not
> released.
>
> Running the test repeatedly I was able to trigger the OOM killer quite
> easily. The system died with a panic, running out of processes to kill.
>
> The symptoms look like swap space is only allocated but never released.
>
> A quick look at the swapping code in ttm_tt.c doesn't show any obvious
> problems. I'm assuming that fput should free swap space. That should
> happen when BOs are swapped back in, or destroyed. As far as I can tell,
> amdgpu doesn't use persistent swap space, so I'm ignoring
> TTM_PAGE_FLAG_PERSISTENT_SWAP.
>
> Any other ideas or pointers?
>
> Thanks,
> Â Felix
>
