Until now ttm stored a single pipelined eviction fence which means drivers had to use a single entity for these evictions.
To lift this requirement, this commit allows up to 8 entities to be used.
Ideally a dma_resv object would have been used as a container of the eviction fences, but the locking rules makes it complex. dma_resv all have the same ww_class, which means "Attempting to lock more mutexes after ww_acquire_done." is an error.
One alternative considered was to introduced a 2nd ww_class for specific resv to hold a single "transient" lock (= the resv lock would only be held for a short period, without taking any other locks).
The other option, is to statically reserve a fence array, and extend the existing code to deal with N fences, instead of 1.
The driver is still responsible to reserve the correct number of fence slots.
--- v2: - simplified code - dropped n_fences - name changes v3: use ttm_resource_manager_cleanup ---
Signed-off-by: Pierre-Eric Pelloux-Prayer pierre-eric.pelloux-prayer@amd.com --- .../gpu/drm/ttm/tests/ttm_bo_validate_test.c | 11 +++-- drivers/gpu/drm/ttm/tests/ttm_resource_test.c | 5 +- drivers/gpu/drm/ttm/ttm_bo.c | 47 ++++++++++--------- drivers/gpu/drm/ttm/ttm_bo_util.c | 38 ++++++++++++--- drivers/gpu/drm/ttm/ttm_resource.c | 31 +++++++----- include/drm/ttm/ttm_resource.h | 29 ++++++++---- 6 files changed, 104 insertions(+), 57 deletions(-)
diff --git a/drivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c b/drivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c index 3148f5d3dbd6..8f71906c4238 100644 --- a/drivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c +++ b/drivers/gpu/drm/ttm/tests/ttm_bo_validate_test.c @@ -651,7 +651,7 @@ static void ttm_bo_validate_move_fence_signaled(struct kunit *test) int err;
man = ttm_manager_type(priv->ttm_dev, mem_type); - man->move = dma_fence_get_stub(); + man->eviction_fences[0] = dma_fence_get_stub();
bo = ttm_bo_kunit_init(test, test->priv, size, NULL); bo->type = bo_type; @@ -668,7 +668,7 @@ static void ttm_bo_validate_move_fence_signaled(struct kunit *test) KUNIT_EXPECT_EQ(test, ctx.bytes_moved, size);
ttm_bo_put(bo); - dma_fence_put(man->move); + dma_fence_put(man->eviction_fences[0]); }
static const struct ttm_bo_validate_test_case ttm_bo_validate_wait_cases[] = { @@ -732,9 +732,9 @@ static void ttm_bo_validate_move_fence_not_signaled(struct kunit *test)
spin_lock_init(&fence_lock); man = ttm_manager_type(priv->ttm_dev, fst_mem); - man->move = alloc_mock_fence(test); + man->eviction_fences[0] = alloc_mock_fence(test);
- task = kthread_create(threaded_fence_signal, man->move, "move-fence-signal"); + task = kthread_create(threaded_fence_signal, man->eviction_fences[0], "move-fence-signal"); if (IS_ERR(task)) KUNIT_FAIL(test, "Couldn't create move fence signal task\n");
@@ -742,7 +742,8 @@ static void ttm_bo_validate_move_fence_not_signaled(struct kunit *test) err = ttm_bo_validate(bo, placement_val, &ctx_val); dma_resv_unlock(bo->base.resv);
- dma_fence_wait_timeout(man->move, false, MAX_SCHEDULE_TIMEOUT); + dma_fence_wait_timeout(man->eviction_fences[0], false, MAX_SCHEDULE_TIMEOUT); + man->eviction_fences[0] = NULL;
KUNIT_EXPECT_EQ(test, err, 0); KUNIT_EXPECT_EQ(test, ctx_val.bytes_moved, size); diff --git a/drivers/gpu/drm/ttm/tests/ttm_resource_test.c b/drivers/gpu/drm/ttm/tests/ttm_resource_test.c index e6ea2bd01f07..c0e4e35e0442 100644 --- a/drivers/gpu/drm/ttm/tests/ttm_resource_test.c +++ b/drivers/gpu/drm/ttm/tests/ttm_resource_test.c @@ -207,6 +207,7 @@ static void ttm_resource_manager_init_basic(struct kunit *test) struct ttm_resource_test_priv *priv = test->priv; struct ttm_resource_manager *man; size_t size = SZ_16K; + int i;
man = kunit_kzalloc(test, sizeof(*man), GFP_KERNEL); KUNIT_ASSERT_NOT_NULL(test, man); @@ -216,8 +217,8 @@ static void ttm_resource_manager_init_basic(struct kunit *test) KUNIT_ASSERT_PTR_EQ(test, man->bdev, priv->devs->ttm_dev); KUNIT_ASSERT_EQ(test, man->size, size); KUNIT_ASSERT_EQ(test, man->usage, 0); - KUNIT_ASSERT_NULL(test, man->move); - KUNIT_ASSERT_NOT_NULL(test, &man->move_lock); + for (i = 0; i < TTM_NUM_MOVE_FENCES; i++) + KUNIT_ASSERT_NULL(test, man->eviction_fences[i]);
for (int i = 0; i < TTM_MAX_BO_PRIORITY; ++i) KUNIT_ASSERT_TRUE(test, list_empty(&man->lru[i])); diff --git a/drivers/gpu/drm/ttm/ttm_bo.c b/drivers/gpu/drm/ttm/ttm_bo.c index f4d9e68b21e7..0b3732ed6f6c 100644 --- a/drivers/gpu/drm/ttm/ttm_bo.c +++ b/drivers/gpu/drm/ttm/ttm_bo.c @@ -658,34 +658,35 @@ void ttm_bo_unpin(struct ttm_buffer_object *bo) EXPORT_SYMBOL(ttm_bo_unpin);
/* - * Add the last move fence to the BO as kernel dependency and reserve a new - * fence slot. + * Add the pipelined eviction fencesto the BO as kernel dependency and reserve new + * fence slots. */ -static int ttm_bo_add_move_fence(struct ttm_buffer_object *bo, - struct ttm_resource_manager *man, - bool no_wait_gpu) +static int ttm_bo_add_pipelined_eviction_fences(struct ttm_buffer_object *bo, + struct ttm_resource_manager *man, + bool no_wait_gpu) { struct dma_fence *fence; - int ret; + int i;
- spin_lock(&man->move_lock); - fence = dma_fence_get(man->move); - spin_unlock(&man->move_lock); + spin_lock(&man->eviction_lock); + for (i = 0; i < TTM_NUM_MOVE_FENCES; i++) { + fence = man->eviction_fences[i]; + if (!fence) + continue;
- if (!fence) - return 0; - - if (no_wait_gpu) { - ret = dma_fence_is_signaled(fence) ? 0 : -EBUSY; - dma_fence_put(fence); - return ret; + if (no_wait_gpu) { + if (!dma_fence_is_signaled(fence)) { + spin_unlock(&man->eviction_lock); + return -EBUSY; + } + } else { + dma_resv_add_fence(bo->base.resv, fence, DMA_RESV_USAGE_KERNEL); + } } + spin_unlock(&man->eviction_lock);
- dma_resv_add_fence(bo->base.resv, fence, DMA_RESV_USAGE_KERNEL); - - ret = dma_resv_reserve_fences(bo->base.resv, 1); - dma_fence_put(fence); - return ret; + /* TODO: this call should be removed. */ + return dma_resv_reserve_fences(bo->base.resv, 1); }
/** @@ -718,7 +719,7 @@ static int ttm_bo_alloc_resource(struct ttm_buffer_object *bo, int i, ret;
ticket = dma_resv_locking_ctx(bo->base.resv); - ret = dma_resv_reserve_fences(bo->base.resv, 1); + ret = dma_resv_reserve_fences(bo->base.resv, TTM_NUM_MOVE_FENCES); if (unlikely(ret)) return ret;
@@ -757,7 +758,7 @@ static int ttm_bo_alloc_resource(struct ttm_buffer_object *bo, return ret; }
- ret = ttm_bo_add_move_fence(bo, man, ctx->no_wait_gpu); + ret = ttm_bo_add_pipelined_eviction_fences(bo, man, ctx->no_wait_gpu); if (unlikely(ret)) { ttm_resource_free(bo, res); if (ret == -EBUSY) diff --git a/drivers/gpu/drm/ttm/ttm_bo_util.c b/drivers/gpu/drm/ttm/ttm_bo_util.c index acbbca9d5c92..2ff35d55e462 100644 --- a/drivers/gpu/drm/ttm/ttm_bo_util.c +++ b/drivers/gpu/drm/ttm/ttm_bo_util.c @@ -258,7 +258,7 @@ static int ttm_buffer_object_transfer(struct ttm_buffer_object *bo, ret = dma_resv_trylock(&fbo->base.base._resv); WARN_ON(!ret);
- ret = dma_resv_reserve_fences(&fbo->base.base._resv, 1); + ret = dma_resv_reserve_fences(&fbo->base.base._resv, TTM_NUM_MOVE_FENCES); if (ret) { dma_resv_unlock(&fbo->base.base._resv); kfree(fbo); @@ -646,20 +646,44 @@ static void ttm_bo_move_pipeline_evict(struct ttm_buffer_object *bo, { struct ttm_device *bdev = bo->bdev; struct ttm_resource_manager *from; + struct dma_fence *tmp; + int i;
from = ttm_manager_type(bdev, bo->resource->mem_type);
/** * BO doesn't have a TTM we need to bind/unbind. Just remember - * this eviction and free up the allocation + * this eviction and free up the allocation. + * The fence will be saved in the first free slot or in the slot + * already used to store a fence from the same context. Since + * drivers can't use more than TTM_NUM_MOVE_FENCES contexts for + * evictions we should always find a slot to use. */ - spin_lock(&from->move_lock); - if (!from->move || dma_fence_is_later(fence, from->move)) { - dma_fence_put(from->move); - from->move = dma_fence_get(fence); + spin_lock(&from->eviction_lock); + for (i = 0; i < TTM_NUM_MOVE_FENCES; i++) { + tmp = from->eviction_fences[i]; + if (!tmp) + break; + if (fence->context != tmp->context) + continue; + if (dma_fence_is_later(fence, tmp)) { + dma_fence_put(tmp); + break; + } + goto unlock; + } + if (i < TTM_NUM_MOVE_FENCES) { + from->eviction_fences[i] = dma_fence_get(fence); + } else { + WARN(1, "not enough fence slots for all fence contexts"); + spin_unlock(&from->eviction_lock); + dma_fence_wait(fence, false); + goto end; } - spin_unlock(&from->move_lock);
+unlock: + spin_unlock(&from->eviction_lock); +end: ttm_resource_free(bo, &bo->resource); }
diff --git a/drivers/gpu/drm/ttm/ttm_resource.c b/drivers/gpu/drm/ttm/ttm_resource.c index e2c82ad07eb4..62c34cafa387 100644 --- a/drivers/gpu/drm/ttm/ttm_resource.c +++ b/drivers/gpu/drm/ttm/ttm_resource.c @@ -523,14 +523,15 @@ void ttm_resource_manager_init(struct ttm_resource_manager *man, { unsigned i;
- spin_lock_init(&man->move_lock); man->bdev = bdev; man->size = size; man->usage = 0;
for (i = 0; i < TTM_MAX_BO_PRIORITY; ++i) INIT_LIST_HEAD(&man->lru[i]); - man->move = NULL; + spin_lock_init(&man->eviction_lock); + for (i = 0; i < TTM_NUM_MOVE_FENCES; i++) + man->eviction_fences[i] = NULL; } EXPORT_SYMBOL(ttm_resource_manager_init);
@@ -551,7 +552,7 @@ int ttm_resource_manager_evict_all(struct ttm_device *bdev, .no_wait_gpu = false, }; struct dma_fence *fence; - int ret; + int ret, i;
do { ret = ttm_bo_evict_first(bdev, man, &ctx); @@ -561,18 +562,24 @@ int ttm_resource_manager_evict_all(struct ttm_device *bdev, if (ret && ret != -ENOENT) return ret;
- spin_lock(&man->move_lock); - fence = dma_fence_get(man->move); - spin_unlock(&man->move_lock); + ret = 0;
- if (fence) { - ret = dma_fence_wait(fence, false); - dma_fence_put(fence); - if (ret) - return ret; + spin_lock(&man->eviction_lock); + for (i = 0; i < TTM_NUM_MOVE_FENCES; i++) { + fence = man->eviction_fences[i]; + if (fence && !dma_fence_is_signaled(fence)) { + dma_fence_get(fence); + spin_unlock(&man->eviction_lock); + ret = dma_fence_wait(fence, false); + dma_fence_put(fence); + if (ret) + return ret; + spin_lock(&man->eviction_lock); + } } + spin_unlock(&man->eviction_lock);
- return 0; + return ret; } EXPORT_SYMBOL(ttm_resource_manager_evict_all);
diff --git a/include/drm/ttm/ttm_resource.h b/include/drm/ttm/ttm_resource.h index f49daa504c36..50e6added509 100644 --- a/include/drm/ttm/ttm_resource.h +++ b/include/drm/ttm/ttm_resource.h @@ -50,6 +50,15 @@ struct io_mapping; struct sg_table; struct scatterlist;
+/** + * define TTM_NUM_MOVE_FENCES - How many entities can be used for evictions + * + * Pipelined evictions can be spread on multiple entities. This + * is the max number of entities that can be used by the driver + * for that purpose. + */ +#define TTM_NUM_MOVE_FENCES 8 + /** * enum ttm_lru_item_type - enumerate ttm_lru_item subclasses */ @@ -180,8 +189,8 @@ struct ttm_resource_manager_func { * @size: Size of the managed region. * @bdev: ttm device this manager belongs to * @func: structure pointer implementing the range manager. See above - * @move_lock: lock for move fence - * @move: The fence of the last pipelined move operation. + * @eviction_lock: lock for eviction fences + * @eviction_fences: The fences of the last pipelined move operation. * @lru: The lru list for this memory type. * * This structure is used to identify and manage memory types for a device. @@ -195,12 +204,12 @@ struct ttm_resource_manager { struct ttm_device *bdev; uint64_t size; const struct ttm_resource_manager_func *func; - spinlock_t move_lock;
- /* - * Protected by @move_lock. + /* This is very similar to a dma_resv object, but locking rules make + * it difficult to use one in this context. */ - struct dma_fence *move; + spinlock_t eviction_lock; + struct dma_fence *eviction_fences[TTM_NUM_MOVE_FENCES];
/* * Protected by the bdev->lru_lock. @@ -421,8 +430,12 @@ static inline bool ttm_resource_manager_used(struct ttm_resource_manager *man) static inline void ttm_resource_manager_cleanup(struct ttm_resource_manager *man) { - dma_fence_put(man->move); - man->move = NULL; + int i; + + for (i = 0; i < TTM_NUM_MOVE_FENCES; i++) { + dma_fence_put(man->eviction_fences[i]); + man->eviction_fences[i] = NULL; + } }
void ttm_lru_bulk_move_init(struct ttm_lru_bulk_move *bulk);