[PATCH 3/3] drm/amdgpu: stop evicting busy PDs/PTs

[Zeng, Oak]

Should we even consider not evicting all PDs/PTs, busy or not. See PDs/PTs only use a tiny bit (roughly ~0.05%) of the total memory. You really don't get much memory when you evict them. But I doubt the evict/restore performance penalty is big.

Thanks,
Oak

-----Original Message-----
From: amd-gfx <amd-gfx-bounces at lists.freedesktop.org> On Behalf Of Christian König
Sent: Friday, March 8, 2019 9:32 AM
To: amd-gfx at lists.freedesktop.org
Subject: [PATCH 3/3] drm/amdgpu: stop evicting busy PDs/PTs

Otherwise we won't be able to cleanly handle page faults.

Signed-off-by: Christian König <christian.koenig at amd.com>
---
 drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c | 7 +++++++
 1 file changed, 7 insertions(+)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
index cd0ccfbbcb84..c1240bf243ba 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c
@@ -1371,6 +1371,13 @@ static bool amdgpu_ttm_bo_eviction_valuable(struct ttm_buffer_object *bo,
 	struct dma_fence *f;
 	int i;
 
+	/* Don't evict VM page tables while they are busy, otherwise we can't
+	 * cleanly handle page faults.
+	 */
+	if (bo->type == ttm_bo_type_kernel &&
+	    !reservation_object_test_signaled_rcu(bo->resv, true))
+		return false;
+
 	/* If bo is a KFD BO, check if the bo belongs to the current process.
 	 * If true, then return false as any KFD process needs all its BOs to
 	 * be resident to run successfully
-- 
2.17.1

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