[PATCH] drm/amdgpu: Add preferred_domain check when determine XGMI state

[Kuehling, Felix]

On 2019-03-26 4:35 p.m., Liu, Shaoyun wrote:
> Avoid unnecessary XGMI hight pstate trigger when mapping none-vram memory for peer device
>
> Change-Id: I1881deff3da19f1f4b58d5765db03a590092a5b2
> Signed-off-by: shaoyunl <shaoyun.liu at amd.com>
> ---
>   drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c | 11 +++++++++++
>   drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c  |  3 ++-
>   2 files changed, 13 insertions(+), 1 deletion(-)
>
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c
> index a82c3b1..a0f56e4 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_gem.c
> @@ -666,6 +666,8 @@ int amdgpu_gem_op_ioctl(struct drm_device *dev, void *data,
>   	struct amdgpu_device *adev = dev->dev_private;
>   	struct drm_amdgpu_gem_op *args = data;
>   	struct drm_gem_object *gobj;
> +	struct amdgpu_vm_bo_base *base;
> +	struct amdgpu_bo_va *bo_va;
>   	struct amdgpu_bo *robj;
>   	int r;
>   
> @@ -704,6 +706,15 @@ int amdgpu_gem_op_ioctl(struct drm_device *dev, void *data,
>   			amdgpu_bo_unreserve(robj);
>   			break;
>   		}
> +		for (base = robj->vm_bo; base; base = base->next) {
> +			bo_va = container_of(base, struct amdgpu_bo_va, base);
> +			if (bo_va && bo_va->is_xgmi) {

The point here is to prevent transitions where a mapping moves from 
is_xgmi => !is_xgmi or from !is_xgmi => is_xgmi, because that would 
potentially require a XGMI pstate change.

This check catches the case of is_xgmi => !is_xgmi, but not the other 
way around. I think you should drop the is_xgmi condition here. Any BO 
that's shared between multiple GPUs should return -EINVAL here because 
moving it could result in an XGMI pstate change. It doesn't matter 
whether it's currently using XGMI or not.

Regards,
   Felix

> +				r = -EINVAL;
> +				amdgpu_bo_unreserve(robj);
> +				goto out;
> +			}
> +		}
> +
>   		robj->preferred_domains = args->value & (AMDGPU_GEM_DOMAIN_VRAM |
>   							AMDGPU_GEM_DOMAIN_GTT |
>   							AMDGPU_GEM_DOMAIN_CPU);
> diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
> index 76eee7e..8ed23d2 100644
> --- a/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
> +++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_vm.c
> @@ -2048,7 +2048,8 @@ struct amdgpu_bo_va *amdgpu_vm_bo_add(struct amdgpu_device *adev,
>   	INIT_LIST_HEAD(&bo_va->valids);
>   	INIT_LIST_HEAD(&bo_va->invalids);
>   
> -	if (bo && amdgpu_xgmi_same_hive(adev, amdgpu_ttm_adev(bo->tbo.bdev))) {
> +	if (bo && amdgpu_xgmi_same_hive(adev, amdgpu_ttm_adev(bo->tbo.bdev)) &&
> +	    (bo->preferred_domains & AMDGPU_GEM_DOMAIN_VRAM)) {
>   		bo_va->is_xgmi = true;
>   		mutex_lock(&adev->vm_manager.lock_pstate);
>   		/* Power up XGMI if it can be potentially used */