Re: [PATCH 5/6] drm/amdgpu: save the PD addr before scheduling the job

["Christian König" <deathsimple@vodafone.de>]

Am 16.06.2016 um 10:33 schrieb zhoucm1:
>
>
> On 2016年06月15日 19:44, Christian König wrote:
>> From: Christian König <christian.koenig@amd.com>
>>
>> When we pipeline evictions the page directory could already be
>> moving somewhere else when grab_id is called.
> Isn't PD bo protected by job fence?
> I think before job fence is signalled, the PD bo is safe, there 
> shouldn't be a chance to evict PD bo.

The crux here is that we start to pipeline BO evictions (we plan them 
but don't execute them immediately).

E.g. the eviction won't happen before the protecting fence is signaled, 
but we have it planned and so the address returned by 
amdgpu_bo_gpu_offset() is already the new one.

Regards,
Christian.

>
> Regards,
> David Zhou
>>
>> Signed-off-by: Christian König <christian.koenig@amd.com>
>> ---
>>   drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c | 2 ++
>>   drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c | 6 ++----
>>   2 files changed, 4 insertions(+), 4 deletions(-)
>>
>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c 
>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
>> index a3d7d13..850c4dd 100644
>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_cs.c
>> @@ -661,6 +661,8 @@ static int amdgpu_cs_ib_vm_chunk(struct 
>> amdgpu_device *adev,
>>           }
>>       }
>>   +    p->job->vm_pd_addr = amdgpu_bo_gpu_offset(vm->page_directory);
>> +
>>       r = amdgpu_bo_vm_update_pte(p, vm);
>>       if (!r)
>>           amdgpu_cs_sync_rings(p);
>> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c 
>> b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
>> index d3e0576..82efb40 100644
>> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
>> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
>> @@ -177,7 +177,6 @@ int amdgpu_vm_grab_id(struct amdgpu_vm *vm, 
>> struct amdgpu_ring *ring,
>>                 struct amdgpu_sync *sync, struct fence *fence,
>>                 unsigned *vm_id, uint64_t *vm_pd_addr)
>>   {
>> -    uint64_t pd_addr = amdgpu_bo_gpu_offset(vm->page_directory);
>>       struct amdgpu_device *adev = ring->adev;
>>       struct fence *updates = sync->last_vm_update;
>>       struct amdgpu_vm_id *id, *idle;
>> @@ -250,7 +249,7 @@ int amdgpu_vm_grab_id(struct amdgpu_vm *vm, 
>> struct amdgpu_ring *ring,
>>           if (atomic64_read(&id->owner) != vm->client_id)
>>               continue;
>>   -        if (pd_addr != id->pd_gpu_addr)
>> +        if (*vm_pd_addr != id->pd_gpu_addr)
>>               continue;
>>             if (!same_ring &&
>> @@ -298,14 +297,13 @@ int amdgpu_vm_grab_id(struct amdgpu_vm *vm, 
>> struct amdgpu_ring *ring,
>>       fence_put(id->flushed_updates);
>>       id->flushed_updates = fence_get(updates);
>>   -    id->pd_gpu_addr = pd_addr;
>> +    id->pd_gpu_addr = *vm_pd_addr;
>>         list_move_tail(&id->list, &adev->vm_manager.ids_lru);
>>       atomic64_set(&id->owner, vm->client_id);
>>       vm->ids[ring->idx] = id;
>>         *vm_id = id - adev->vm_manager.ids;
>> -    *vm_pd_addr = pd_addr;
>>       trace_amdgpu_vm_grab_id(vm, ring->idx, *vm_id, *vm_pd_addr);
>>     error:
>
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