[PATCH 4/4] drm/amdgpu: check whether the vmid can be reused first

[Christian König]

NAK, it is intentionally done like this to avoid starvation of processes.

In other words we assign a VMID only when there is at least one free.

Regards,
Christian.

Am 10.05.2017 um 09:31 schrieb Chunming Zhou:
> Change-Id: If24a62b9c3097c9b040225ab0e768145b7a3db1e
> Signed-off-by: Chunming Zhou <David1.Zhou at amd.com>
> ---
>   drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c | 92 +++++++++++++++++-----------------
>   1 file changed, 47 insertions(+), 45 deletions(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
> index bbb3587..6259608 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
> @@ -492,51 +492,6 @@ int amdgpu_vm_grab_id(struct amdgpu_vm *vm, struct amdgpu_ring *ring,
>   		mutex_unlock(&id_mgr->lock);
>   		return r;
>   	}
> -	fences = kmalloc_array(sizeof(void *), id_mgr->num_ids, GFP_KERNEL);
> -	if (!fences) {
> -		mutex_unlock(&id_mgr->lock);
> -		return -ENOMEM;
> -	}
> -	/* Check if we have an idle VMID */
> -	i = 0;
> -	list_for_each_entry(idle, &id_mgr->ids_lru, list) {
> -		fences[i] = amdgpu_sync_peek_fence(&idle->active, ring);
> -		if (!fences[i])
> -			break;
> -		++i;
> -	}
> -
> -	/* If we can't find a idle VMID to use, wait till one becomes available */
> -	if (&idle->list == &id_mgr->ids_lru) {
> -		u64 fence_context = adev->vm_manager.fence_context + ring->idx;
> -		unsigned seqno = ++adev->vm_manager.seqno[ring->idx];
> -		struct fence_array *array;
> -		unsigned j;
> -
> -		for (j = 0; j < i; ++j)
> -			fence_get(fences[j]);
> -
> -		array = fence_array_create(i, fences, fence_context,
> -					   seqno, true);
> -		if (!array) {
> -			for (j = 0; j < i; ++j)
> -				fence_put(fences[j]);
> -			kfree(fences);
> -			r = -ENOMEM;
> -			goto error;
> -		}
> -
> -
> -		r = amdgpu_sync_fence(ring->adev, sync, &array->base);
> -		fence_put(&array->base);
> -		if (r)
> -			goto error;
> -
> -		mutex_unlock(&id_mgr->lock);
> -		return 0;
> -
> -	}
> -	kfree(fences);
>   
>   	job->vm_needs_flush = false;
>   	/* Check if we can use a VMID already assigned to this VM */
> @@ -586,6 +541,53 @@ int amdgpu_vm_grab_id(struct amdgpu_vm *vm, struct amdgpu_ring *ring,
>   
>   	};
>   
> +	fences = kmalloc_array(sizeof(void *), id_mgr->num_ids, GFP_KERNEL);
> +	if (!fences) {
> +		mutex_unlock(&id_mgr->lock);
> +		return -ENOMEM;
> +	}
> +	/* Check if we have an idle VMID */
> +	i = 0;
> +	list_for_each_entry(idle, &id_mgr->ids_lru, list) {
> +		fences[i] = amdgpu_sync_peek_fence(&idle->active, ring);
> +		if (!fences[i])
> +			break;
> +		++i;
> +	}
> +
> +	/* If we can't find a idle VMID to use, wait till one becomes available */
> +	if (&idle->list == &id_mgr->ids_lru) {
> +		u64 fence_context = adev->vm_manager.fence_context + ring->idx;
> +		unsigned seqno = ++adev->vm_manager.seqno[ring->idx];
> +		struct fence_array *array;
> +		unsigned j;
> +
> +		for (j = 0; j < i; ++j)
> +			fence_get(fences[j]);
> +
> +		array = fence_array_create(i, fences, fence_context,
> +					   seqno, true);
> +		if (!array) {
> +			for (j = 0; j < i; ++j)
> +				fence_put(fences[j]);
> +			kfree(fences);
> +			r = -ENOMEM;
> +			goto error;
> +		}
> +
> +
> +		r = amdgpu_sync_fence(ring->adev, sync, &array->base);
> +		fence_put(&array->base);
> +		if (r)
> +			goto error;
> +
> +		mutex_unlock(&id_mgr->lock);
> +		return 0;
> +
> +	}
> +	kfree(fences);
> +
> +
>   	/* Still no ID to use? Then use the idle one found earlier */
>   	id = idle;
>