Am 03.01.2018 um 11:43 schrieb Chunming Zhou:


On 2018年01月03日 17:25, Christian König wrote:
Am 03.01.2018 um 09:10 schrieb Zhou, David(ChunMing):

On 2018年01月02日 22:47, Christian König wrote:
Try to lock moved BOs if it's successful we can update the
PTEs directly to the new location.

v2: rebase

Signed-off-by: Christian König <[email protected]>
---
   drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c | 15 ++++++++++++++-
   1 file changed, 14 insertions(+), 1 deletion(-)

diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
index 3632c69f1814..c1c5ccdee783 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
@@ -1697,18 +1697,31 @@ int amdgpu_vm_handle_moved(struct amdgpu_device *adev,
       spin_lock(&vm->status_lock);
       while (!list_empty(&vm->moved)) {
           struct amdgpu_bo_va *bo_va;
+        struct reservation_object *resv;
              bo_va = list_first_entry(&vm->moved,
               struct amdgpu_bo_va, base.vm_status);
           spin_unlock(&vm->status_lock);
   +        resv = bo_va->base.bo->tbo.resv;
+
           /* Per VM BOs never need to bo cleared in the page tables */
This reminders us Per-VM-BOs need to cleared as well after we allow to
evict/swap out per-vm-bos.

Actually they don't. The page tables only need to be valid during CS.

So what happens is that the per VM-BOs are validated in right before we call amdgpu_vm_handle_moved().
Yeah, agree it for per-vm-bo situation after I checked all adding moved list cases:
1. validate pt bos
2. bo invalidate
3. insert_map for per-vm-bo
item #1 and #3 both are per-vm-bo, they are already validated before handle_moved().

For item #2, there are three places to call it:
a. amdgpu_bo_vm_update_pte in CS for amdgpu_vm_debug
b. amdgpu_gem_op_ioctl, but it is for evicted list, nothing with moved list.
c. amdgpu_bo_move_notify when bo validate.

For c case, your optimization is valid, we don't need clear for validate bo.
But for a case, yours will break amdgpu_vm_debug functionality.

Right?

Interesting point, but no that should be handled as well.

The vm_debug handling is only for the BOs on the BO-list. E.g. per VM BOs are never handled here.

Regards,
Christian.


Regards,
David Zhou


Regards,
Christian.


Regards,
David Zhou
-        clear = bo_va->base.bo->tbo.resv != vm->root.base.bo->tbo.resv;
+        if (resv == vm->root.base.bo->tbo.resv)
+            clear = false;
+        /* Try to reserve the BO to avoid clearing its ptes */
+        else if (reservation_object_trylock(resv))
+            clear = false;
+        /* Somebody else is using the BO right now */
+        else
+            clear = true;
              r = amdgpu_vm_bo_update(adev, bo_va, clear);
           if (r)
               return r;
   +        if (!clear && resv != vm->root.base.bo->tbo.resv)
+            reservation_object_unlock(resv);
+
           spin_lock(&vm->status_lock);
       }
       spin_unlock(&vm->status_lock);



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