Commit abb50d67 authored by Thomas Hellström's avatar Thomas Hellström
Browse files

drm/ttm, drm/amdgpu: Allow the driver some control over swapping 



We are calling the eviction_valuable driver callback at eviction time to
determine whether we actually can evict a buffer object.
The upcoming i915 TTM backend needs the same functionality for swapout,
and that might actually be beneficial to other drivers as well.

Add an eviction_valuable call also in the swapout path. Try to keep the
current behaviour for all drivers by returning true if the buffer object
is already in the TTM_PL_SYSTEM placement. We change behaviour for the
case where a buffer object is in a TT backed placement when swapped out,
in which case the drivers normal eviction_valuable path is run.

Reviewed-by: default avatarMaarten Lankhorst <maarten.lankhorst@linux.intel.com>
Cc: Christian König <christian.koenig@amd.com>
Signed-off-by: default avatarThomas Hellström <thomas.hellstrom@linux.intel.com>
Acked-by: default avatarChristian König <christian.koenig@amd.com>
Link: https://lore.kernel.org/r/20210602083818.241793-8-thomas.hellstrom@linux.intel.com
Link: https://patchwork.freedesktop.org/patch/msgid/20210602083818.241793-8-thomas.hellstrom@linux.intel.com
parent a3be8cd7

drivers/gpu/drm/amd/amdgpu/amdgpu_ttm.c

+4 −0
Original line number Diff line number Diff line
@@ -1331,6 +1331,10 @@ static bool amdgpu_ttm_bo_eviction_valuable(struct ttm_buffer_object *bo, 
	struct dma_fence *f;

	int i;



	/* Swapout? */

	if (bo->resource->mem_type == TTM_PL_SYSTEM)

		return true;



	if (bo->type == ttm_bo_type_kernel &&

	    !amdgpu_vm_evictable(ttm_to_amdgpu_bo(bo)))

		return false;

drivers/gpu/drm/ttm/ttm_bo.c

+30 −16
Original line number Diff line number Diff line
@@ -538,6 +538,10 @@ static int ttm_bo_evict(struct ttm_buffer_object *bo, 
bool ttm_bo_eviction_valuable(struct ttm_buffer_object *bo,

			      const struct ttm_place *place)

{

	dma_resv_assert_held(bo->base.resv);

	if (bo->resource->mem_type == TTM_PL_SYSTEM)

		return true;



	/* Don't evict this BO if it's outside of the

	 * requested placement range

	 */
@@ -560,7 +564,9 @@ EXPORT_SYMBOL(ttm_bo_eviction_valuable); 
 * b. Otherwise, trylock it.

 */

static bool ttm_bo_evict_swapout_allowable(struct ttm_buffer_object *bo,

			struct ttm_operation_ctx *ctx, bool *locked, bool *busy)

					   struct ttm_operation_ctx *ctx,

					   const struct ttm_place *place,

					   bool *locked, bool *busy)

{

	bool ret = false;
@@ -578,6 +584,14 @@ static bool ttm_bo_evict_swapout_allowable(struct ttm_buffer_object *bo, 
			*busy = !ret;

	}



	if (ret && place && !bo->bdev->funcs->eviction_valuable(bo, place)) {

		ret = false;

		if (*locked) {

			dma_resv_unlock(bo->base.resv);

			*locked = false;

		}

	}



	return ret;

}
@@ -632,20 +646,14 @@ int ttm_mem_evict_first(struct ttm_device *bdev, 
		list_for_each_entry(bo, &man->lru[i], lru) {

			bool busy;



			if (!ttm_bo_evict_swapout_allowable(bo, ctx, &locked,

							    &busy)) {

			if (!ttm_bo_evict_swapout_allowable(bo, ctx, place,

							    &locked, &busy)) {

				if (busy && !busy_bo && ticket !=

				    dma_resv_locking_ctx(bo->base.resv))

					busy_bo = bo;

				continue;

			}



			if (place && !bdev->funcs->eviction_valuable(bo,

								      place)) {

				if (locked)

					dma_resv_unlock(bo->base.resv);

				continue;

			}

			if (!ttm_bo_get_unless_zero(bo)) {

				if (locked)

					dma_resv_unlock(bo->base.resv);
@@ -1116,10 +1124,19 @@ EXPORT_SYMBOL(ttm_bo_wait); 
int ttm_bo_swapout(struct ttm_buffer_object *bo, struct ttm_operation_ctx *ctx,

		   gfp_t gfp_flags)

{

	struct ttm_place place;

	bool locked;

	int ret;



	if (!ttm_bo_evict_swapout_allowable(bo, ctx, &locked, NULL))

	/*

	 * While the bo may already reside in SYSTEM placement, set

	 * SYSTEM as new placement to cover also the move further below.

	 * The driver may use the fact that we're moving from SYSTEM

	 * as an indication that we're about to swap out.

	 */

	memset(&place, 0, sizeof(place));

	place.mem_type = TTM_PL_SYSTEM;

	if (!ttm_bo_evict_swapout_allowable(bo, ctx, &place, &locked, NULL))

		return -EBUSY;



	if (!ttm_bo_get_unless_zero(bo)) {
@@ -1144,13 +1161,9 @@ int ttm_bo_swapout(struct ttm_buffer_object *bo, struct ttm_operation_ctx *ctx, 
	if (bo->resource->mem_type != TTM_PL_SYSTEM) {

		struct ttm_operation_ctx ctx = { false, false };

		struct ttm_resource *evict_mem;

		struct ttm_place place, hop;

		struct ttm_place hop;



		memset(&place, 0, sizeof(place));

		memset(&hop, 0, sizeof(hop));



		place.mem_type = TTM_PL_SYSTEM;



		ret = ttm_resource_alloc(bo, &place, &evict_mem);

		if (unlikely(ret))

			goto out;
@@ -1178,6 +1191,7 @@ int ttm_bo_swapout(struct ttm_buffer_object *bo, struct ttm_operation_ctx *ctx, 
	if (bo->bdev->funcs->swap_notify)

		bo->bdev->funcs->swap_notify(bo);



	if (ttm_tt_is_populated(bo->ttm))

		ret = ttm_tt_swapout(bo->bdev, bo->ttm, gfp_flags);

out: