[PATCH] Sync KFD Eviction fence only for move / evict

Harish Kasiviswanathan Harish.Kasiviswanathan at amd.com
Thu Oct 19 17:40:35 UTC 2017

What is KFD eviction fence?
        For KFD submissions are done by user mode process. If any of user mode
        queues are active, KFD driver must ensure that all the BOs associated
        with that process must be resident. This is ensured by adding a
        blanket eviction fence to all of the process BOs.

When will the eviction fence be signaled?
        Eviction fence will be signaled only when the system is low on memory
        and TTM wants to move / evict BOs. Before signaling the fence KFD
        driver quiesces all the queues that belongs to that process. After a
        timeout the reverse is done to make the process queues active again.

What is the current issue?
        Interop BOs. KFD fence is attached to shared BO. So when graphics
        tries do a CS using this BO, KFD driver mistakes this to be an
        eviction. This patch is to solve this issue.

Harish Kasiviswanathan (1):
  drm/amdgpu: Sync KFD fence only for move/evict

 drivers/gpu/drm/amd/amdgpu/amdgpu_sync.c | 8 +++++---
 1 file changed, 5 insertions(+), 3 deletions(-)


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