Re: [PATCH v4 1/2] drm/ttm: Move swapped objects off the manager's LRU list

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Am 04.09.24 um 09:08 schrieb Thomas Hellström:

Resources of swapped objects remains on the TTM_PL_SYSTEM manager's
LRU list, which is bad for the LRU walk efficiency.

Rename the device-wide "pinned" list to "unevictable" and move
also resources of swapped-out objects to that list.

An alternative would be to create an "UNEVICTABLE" priority to
be able to keep the pinned- and swapped objects on their
respective manager's LRU without affecting the LRU walk efficiency.

v2:
- Remove a bogus WARN_ON (Christian König)
- Update ttm_resource_[add|del] bulk move (Christian König)
- Fix TTM KUNIT tests (Intel CI)
v3:
- Check for non-NULL bo->resource in ttm_bo_populate().
v4:
- Don't move to LRU tail during swapout until the resource
   is properly swapped or there was a swapout failure.
   (Intel Ci)
- Add a newline after checkpatch check.

Cc: Christian König <christian.koenig@xxxxxxx>
Cc: Matthew Brost <matthew.brost@xxxxxxxxx>
Cc: <dri-devel@xxxxxxxxxxxxxxxxxxxxx>
Signed-off-by: Thomas Hellström <thomas.hellstrom@xxxxxxxxxxxxxxx>


I really wonder if having a SWAPPED wouldn't be cleaner in the long run.
Anyway, that seems to work for now. So patch is Reviewed-by: Christian König <christian.koenig@xxxxxxx>. 

Regards,
Christian.


---
  drivers/gpu/drm/i915/gem/i915_gem_ttm.c       |  2 +-
  drivers/gpu/drm/i915/gem/i915_gem_ttm_move.c  |  2 +-
  drivers/gpu/drm/i915/gem/i915_gem_ttm_pm.c    |  4 +-
  drivers/gpu/drm/ttm/tests/ttm_bo_test.c       |  4 +-
  drivers/gpu/drm/ttm/tests/ttm_resource_test.c |  6 +-
  drivers/gpu/drm/ttm/ttm_bo.c                  | 59 ++++++++++++++++++-
  drivers/gpu/drm/ttm/ttm_bo_util.c             |  6 +-
  drivers/gpu/drm/ttm/ttm_bo_vm.c               |  2 +-
  drivers/gpu/drm/ttm/ttm_device.c              |  4 +-
  drivers/gpu/drm/ttm/ttm_resource.c            | 15 +++--
  drivers/gpu/drm/ttm/ttm_tt.c                  |  3 +
  drivers/gpu/drm/xe/xe_bo.c                    |  4 +-
  include/drm/ttm/ttm_bo.h                      |  2 +
  include/drm/ttm/ttm_device.h                  |  5 +-
  include/drm/ttm/ttm_tt.h                      |  5 ++
  15 files changed, 96 insertions(+), 27 deletions(-)

diff --git a/drivers/gpu/drm/i915/gem/i915_gem_ttm.c b/drivers/gpu/drm/i915/gem/i915_gem_ttm.c
index 5c72462d1f57..7de284766f82 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_ttm.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_ttm.c
@@ -808,7 +808,7 @@ static int __i915_ttm_get_pages(struct drm_i915_gem_object *obj,
  	}
if (bo->ttm && !ttm_tt_is_populated(bo->ttm)) { 
-		ret = ttm_tt_populate(bo->bdev, bo->ttm, &ctx);
+		ret = ttm_bo_populate(bo, &ctx);
  		if (ret)
  			return ret;
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_ttm_move.c b/drivers/gpu/drm/i915/gem/i915_gem_ttm_move.c 
index 03b00a03a634..041dab543b78 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_ttm_move.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_ttm_move.c
@@ -624,7 +624,7 @@ int i915_ttm_move(struct ttm_buffer_object *bo, bool evict,
/* Populate ttm with pages if needed. Typically system memory. */ 
  	if (ttm && (dst_man->use_tt || (ttm->page_flags & TTM_TT_FLAG_SWAPPED))) {
-		ret = ttm_tt_populate(bo->bdev, ttm, ctx);
+		ret = ttm_bo_populate(bo, ctx);
  		if (ret)
  			return ret;
  	}
diff --git a/drivers/gpu/drm/i915/gem/i915_gem_ttm_pm.c b/drivers/gpu/drm/i915/gem/i915_gem_ttm_pm.c
index ad649523d5e0..61596cecce4d 100644
--- a/drivers/gpu/drm/i915/gem/i915_gem_ttm_pm.c
+++ b/drivers/gpu/drm/i915/gem/i915_gem_ttm_pm.c
@@ -90,7 +90,7 @@ static int i915_ttm_backup(struct i915_gem_apply_to_region *apply,
  		goto out_no_lock;
backup_bo = i915_gem_to_ttm(backup); 
-	err = ttm_tt_populate(backup_bo->bdev, backup_bo->ttm, &ctx);
+	err = ttm_bo_populate(backup_bo, &ctx);
  	if (err)
  		goto out_no_populate;
@@ -189,7 +189,7 @@ static int i915_ttm_restore(struct i915_gem_apply_to_region *apply, 
  	if (!backup_bo->resource)
  		err = ttm_bo_validate(backup_bo, i915_ttm_sys_placement(), &ctx);
  	if (!err)
-		err = ttm_tt_populate(backup_bo->bdev, backup_bo->ttm, &ctx);
+		err = ttm_bo_populate(backup_bo, &ctx);
  	if (!err) {
  		err = i915_gem_obj_copy_ttm(obj, backup, pm_apply->allow_gpu,
  					    false);
diff --git a/drivers/gpu/drm/ttm/tests/ttm_bo_test.c b/drivers/gpu/drm/ttm/tests/ttm_bo_test.c
index f0a7eb62116c..3139fd9128d8 100644
--- a/drivers/gpu/drm/ttm/tests/ttm_bo_test.c
+++ b/drivers/gpu/drm/ttm/tests/ttm_bo_test.c
@@ -308,11 +308,11 @@ static void ttm_bo_unreserve_pinned(struct kunit *test)
  	err = ttm_resource_alloc(bo, place, &res2);
  	KUNIT_ASSERT_EQ(test, err, 0);
  	KUNIT_ASSERT_EQ(test,
-			list_is_last(&res2->lru.link, &priv->ttm_dev->pinned), 1);
+			list_is_last(&res2->lru.link, &priv->ttm_dev->unevictable), 1);
ttm_bo_unreserve(bo); 
  	KUNIT_ASSERT_EQ(test,
-			list_is_last(&res1->lru.link, &priv->ttm_dev->pinned), 1);
+			list_is_last(&res1->lru.link, &priv->ttm_dev->unevictable), 1);
ttm_resource_free(bo, &res1); 
  	ttm_resource_free(bo, &res2);
diff --git a/drivers/gpu/drm/ttm/tests/ttm_resource_test.c b/drivers/gpu/drm/ttm/tests/ttm_resource_test.c
index 22260e7aea58..a9f4b81921c3 100644
--- a/drivers/gpu/drm/ttm/tests/ttm_resource_test.c
+++ b/drivers/gpu/drm/ttm/tests/ttm_resource_test.c
@@ -164,18 +164,18 @@ static void ttm_resource_init_pinned(struct kunit *test)
res = kunit_kzalloc(test, sizeof(*res), GFP_KERNEL); 
  	KUNIT_ASSERT_NOT_NULL(test, res);
-	KUNIT_ASSERT_TRUE(test, list_empty(&bo->bdev->pinned));
+	KUNIT_ASSERT_TRUE(test, list_empty(&bo->bdev->unevictable));
dma_resv_lock(bo->base.resv, NULL); 
  	ttm_bo_pin(bo);
  	ttm_resource_init(bo, place, res);
-	KUNIT_ASSERT_TRUE(test, list_is_singular(&bo->bdev->pinned));
+	KUNIT_ASSERT_TRUE(test, list_is_singular(&bo->bdev->unevictable));
ttm_bo_unpin(bo); 
  	ttm_resource_fini(man, res);
  	dma_resv_unlock(bo->base.resv);
- KUNIT_ASSERT_TRUE(test, list_empty(&bo->bdev->pinned)); 
+	KUNIT_ASSERT_TRUE(test, list_empty(&bo->bdev->unevictable));
  }
static void ttm_resource_fini_basic(struct kunit *test) 
diff --git a/drivers/gpu/drm/ttm/ttm_bo.c b/drivers/gpu/drm/ttm/ttm_bo.c
index 320592435252..875b024913a0 100644
--- a/drivers/gpu/drm/ttm/ttm_bo.c
+++ b/drivers/gpu/drm/ttm/ttm_bo.c
@@ -139,7 +139,7 @@ static int ttm_bo_handle_move_mem(struct ttm_buffer_object *bo,
  			goto out_err;
if (mem->mem_type != TTM_PL_SYSTEM) { 
-			ret = ttm_tt_populate(bo->bdev, bo->ttm, ctx);
+			ret = ttm_bo_populate(bo, ctx);
  			if (ret)
  				goto out_err;
  		}
@@ -1128,9 +1128,20 @@ ttm_bo_swapout_cb(struct ttm_lru_walk *walk, struct ttm_buffer_object *bo)
  	if (bo->bdev->funcs->swap_notify)
  		bo->bdev->funcs->swap_notify(bo);
- if (ttm_tt_is_populated(bo->ttm)) 
+	if (ttm_tt_is_populated(bo->ttm)) {
+		spin_lock(&bo->bdev->lru_lock);
+		ttm_resource_del_bulk_move(bo->resource, bo);
+		spin_unlock(&bo->bdev->lru_lock);
+
  		ret = ttm_tt_swapout(bo->bdev, bo->ttm, swapout_walk->gfp_flags);
+ spin_lock(&bo->bdev->lru_lock); 
+		if (ret)
+			ttm_resource_add_bulk_move(bo->resource, bo);
+		ttm_resource_move_to_lru_tail(bo->resource);
+		spin_unlock(&bo->bdev->lru_lock);
+	}
+
  out:
  	/* Consider -ENOMEM and -ENOSPC non-fatal. */
  	if (ret == -ENOMEM || ret == -ENOSPC)
@@ -1180,3 +1191,47 @@ void ttm_bo_tt_destroy(struct ttm_buffer_object *bo)
  	ttm_tt_destroy(bo->bdev, bo->ttm);
  	bo->ttm = NULL;
  }
+
+/**
+ * ttm_bo_populate() - Ensure that a buffer object has backing pages
+ * @bo: The buffer object
+ * @ctx: The ttm_operation_ctx governing the operation.
+ *
+ * For buffer objects in a memory type whose manager uses
+ * struct ttm_tt for backing pages, ensure those backing pages
+ * are present and with valid content. The bo's resource is also
+ * placed on the correct LRU list if it was previously swapped
+ * out.
+ *
+ * Return: 0 if successful, negative error code on failure.
+ * Note: May return -EINTR or -ERESTARTSYS if @ctx::interruptible
+ * is set to true.
+ */
+int ttm_bo_populate(struct ttm_buffer_object *bo,
+		    struct ttm_operation_ctx *ctx)
+{
+	struct ttm_tt *tt = bo->ttm;
+	bool swapped;
+	int ret;
+
+	dma_resv_assert_held(bo->base.resv);
+
+	if (!tt)
+		return 0;
+
+	swapped = ttm_tt_is_swapped(tt);
+	ret = ttm_tt_populate(bo->bdev, tt, ctx);
+	if (ret)
+		return ret;
+
+	if (swapped && !ttm_tt_is_swapped(tt) && !bo->pin_count &&
+	    bo->resource) {
+		spin_lock(&bo->bdev->lru_lock);
+		ttm_resource_add_bulk_move(bo->resource, bo);
+		ttm_resource_move_to_lru_tail(bo->resource);
+		spin_unlock(&bo->bdev->lru_lock);
+	}
+
+	return 0;
+}
+EXPORT_SYMBOL(ttm_bo_populate);
diff --git a/drivers/gpu/drm/ttm/ttm_bo_util.c b/drivers/gpu/drm/ttm/ttm_bo_util.c
index 3c07f4712d5c..d939925efa81 100644
--- a/drivers/gpu/drm/ttm/ttm_bo_util.c
+++ b/drivers/gpu/drm/ttm/ttm_bo_util.c
@@ -163,7 +163,7 @@ int ttm_bo_move_memcpy(struct ttm_buffer_object *bo,
  	src_man = ttm_manager_type(bdev, src_mem->mem_type);
  	if (ttm && ((ttm->page_flags & TTM_TT_FLAG_SWAPPED) ||
  		    dst_man->use_tt)) {
-		ret = ttm_tt_populate(bdev, ttm, ctx);
+		ret = ttm_bo_populate(bo, ctx);
  		if (ret)
  			return ret;
  	}
@@ -350,7 +350,7 @@ static int ttm_bo_kmap_ttm(struct ttm_buffer_object *bo,
BUG_ON(!ttm); - ret = ttm_tt_populate(bo->bdev, ttm, &ctx); 
+	ret = ttm_bo_populate(bo, &ctx);
  	if (ret)
  		return ret;
@@ -507,7 +507,7 @@ int ttm_bo_vmap(struct ttm_buffer_object *bo, struct iosys_map *map) 
  		pgprot_t prot;
  		void *vaddr;
- ret = ttm_tt_populate(bo->bdev, ttm, &ctx); 
+		ret = ttm_bo_populate(bo, &ctx);
  		if (ret)
  			return ret;
diff --git a/drivers/gpu/drm/ttm/ttm_bo_vm.c b/drivers/gpu/drm/ttm/ttm_bo_vm.c 
index 4212b8c91dd4..2c699ed1963a 100644
--- a/drivers/gpu/drm/ttm/ttm_bo_vm.c
+++ b/drivers/gpu/drm/ttm/ttm_bo_vm.c
@@ -224,7 +224,7 @@ vm_fault_t ttm_bo_vm_fault_reserved(struct vm_fault *vmf,
  		};
ttm = bo->ttm; 
-		err = ttm_tt_populate(bdev, bo->ttm, &ctx);
+		err = ttm_bo_populate(bo, &ctx);
  		if (err) {
  			if (err == -EINTR || err == -ERESTARTSYS ||
  			    err == -EAGAIN)
diff --git a/drivers/gpu/drm/ttm/ttm_device.c b/drivers/gpu/drm/ttm/ttm_device.c
index e7cc4954c1bc..02e797fd1891 100644
--- a/drivers/gpu/drm/ttm/ttm_device.c
+++ b/drivers/gpu/drm/ttm/ttm_device.c
@@ -216,7 +216,7 @@ int ttm_device_init(struct ttm_device *bdev, const struct ttm_device_funcs *func
bdev->vma_manager = vma_manager; 
  	spin_lock_init(&bdev->lru_lock);
-	INIT_LIST_HEAD(&bdev->pinned);
+	INIT_LIST_HEAD(&bdev->unevictable);
  	bdev->dev_mapping = mapping;
  	mutex_lock(&ttm_global_mutex);
  	list_add_tail(&bdev->device_list, &glob->device_list);
@@ -283,7 +283,7 @@ void ttm_device_clear_dma_mappings(struct ttm_device *bdev)
  	struct ttm_resource_manager *man;
  	unsigned int i, j;
- ttm_device_clear_lru_dma_mappings(bdev, &bdev->pinned); 
+	ttm_device_clear_lru_dma_mappings(bdev, &bdev->unevictable);
for (i = TTM_PL_SYSTEM; i < TTM_NUM_MEM_TYPES; ++i) { 
  		man = ttm_manager_type(bdev, i);
diff --git a/drivers/gpu/drm/ttm/ttm_resource.c b/drivers/gpu/drm/ttm/ttm_resource.c
index 6d764ba88aab..93b44043b428 100644
--- a/drivers/gpu/drm/ttm/ttm_resource.c
+++ b/drivers/gpu/drm/ttm/ttm_resource.c
@@ -30,6 +30,7 @@
  #include <drm/ttm/ttm_bo.h>
  #include <drm/ttm/ttm_placement.h>
  #include <drm/ttm/ttm_resource.h>
+#include <drm/ttm/ttm_tt.h>
#include <drm/drm_util.h> @@ -239,7 +240,8 @@ static void ttm_lru_bulk_move_del(struct ttm_lru_bulk_move *bulk, 
  void ttm_resource_add_bulk_move(struct ttm_resource *res,
  				struct ttm_buffer_object *bo)
  {
-	if (bo->bulk_move && !bo->pin_count)
+	if (bo->bulk_move && !bo->pin_count &&
+	    (!bo->ttm || !ttm_tt_is_swapped(bo->ttm)))
  		ttm_lru_bulk_move_add(bo->bulk_move, res);
  }
@@ -247,7 +249,8 @@ void ttm_resource_add_bulk_move(struct ttm_resource *res, 
  void ttm_resource_del_bulk_move(struct ttm_resource *res,
  				struct ttm_buffer_object *bo)
  {
-	if (bo->bulk_move && !bo->pin_count)
+	if (bo->bulk_move && !bo->pin_count &&
+	    (!bo->ttm || !ttm_tt_is_swapped(bo->ttm)))
  		ttm_lru_bulk_move_del(bo->bulk_move, res);
  }
@@ -259,8 +262,8 @@ void ttm_resource_move_to_lru_tail(struct ttm_resource *res) lockdep_assert_held(&bo->bdev->lru_lock); - if (bo->pin_count) { 
-		list_move_tail(&res->lru.link, &bdev->pinned);
+	if (bo->pin_count || (bo->ttm && ttm_tt_is_swapped(bo->ttm))) {
+		list_move_tail(&res->lru.link, &bdev->unevictable);
} else if (bo->bulk_move) { 
  		struct ttm_lru_bulk_move_pos *pos =
@@ -301,8 +304,8 @@ void ttm_resource_init(struct ttm_buffer_object *bo,
man = ttm_manager_type(bo->bdev, place->mem_type); 
  	spin_lock(&bo->bdev->lru_lock);
-	if (bo->pin_count)
-		list_add_tail(&res->lru.link, &bo->bdev->pinned);
+	if (bo->pin_count || (bo->ttm && ttm_tt_is_swapped(bo->ttm)))
+		list_add_tail(&res->lru.link, &bo->bdev->unevictable);
  	else
  		list_add_tail(&res->lru.link, &man->lru[bo->priority]);
  	man->usage += res->size;
diff --git a/drivers/gpu/drm/ttm/ttm_tt.c b/drivers/gpu/drm/ttm/ttm_tt.c
index 4b51b9023126..3baf215eca23 100644
--- a/drivers/gpu/drm/ttm/ttm_tt.c
+++ b/drivers/gpu/drm/ttm/ttm_tt.c
@@ -367,7 +367,10 @@ int ttm_tt_populate(struct ttm_device *bdev,
  	}
  	return ret;
  }
+
+#if IS_ENABLED(CONFIG_DRM_TTM_KUNIT_TEST)
  EXPORT_SYMBOL(ttm_tt_populate);
+#endif
void ttm_tt_unpopulate(struct ttm_device *bdev, struct ttm_tt *ttm) 
  {
diff --git a/drivers/gpu/drm/xe/xe_bo.c b/drivers/gpu/drm/xe/xe_bo.c
index a8e4d46d9123..f34daae2cf2b 100644
--- a/drivers/gpu/drm/xe/xe_bo.c
+++ b/drivers/gpu/drm/xe/xe_bo.c
@@ -892,7 +892,7 @@ int xe_bo_evict_pinned(struct xe_bo *bo)
  		}
  	}
- ret = ttm_tt_populate(bo->ttm.bdev, bo->ttm.ttm, &ctx); 
+	ret = ttm_bo_populate(&bo->ttm, &ctx);
  	if (ret)
  		goto err_res_free;
@@ -945,7 +945,7 @@ int xe_bo_restore_pinned(struct xe_bo *bo) 
  	if (ret)
  		return ret;
- ret = ttm_tt_populate(bo->ttm.bdev, bo->ttm.ttm, &ctx); 
+	ret = ttm_bo_populate(&bo->ttm, &ctx);
  	if (ret)
  		goto err_res_free;
diff --git a/include/drm/ttm/ttm_bo.h b/include/drm/ttm/ttm_bo.h 
index 7b56d1ca36d7..5804408815be 100644
--- a/include/drm/ttm/ttm_bo.h
+++ b/include/drm/ttm/ttm_bo.h
@@ -462,5 +462,7 @@ int ttm_bo_pipeline_gutting(struct ttm_buffer_object *bo);
  pgprot_t ttm_io_prot(struct ttm_buffer_object *bo, struct ttm_resource *res,
  		     pgprot_t tmp);
  void ttm_bo_tt_destroy(struct ttm_buffer_object *bo);
+int ttm_bo_populate(struct ttm_buffer_object *bo,
+		    struct ttm_operation_ctx *ctx);
#endif 
diff --git a/include/drm/ttm/ttm_device.h b/include/drm/ttm/ttm_device.h
index c22f30535c84..438358f72716 100644
--- a/include/drm/ttm/ttm_device.h
+++ b/include/drm/ttm/ttm_device.h
@@ -252,9 +252,10 @@ struct ttm_device {
  	spinlock_t lru_lock;
/** 
-	 * @pinned: Buffer objects which are pinned and so not on any LRU list.
+	 * @unevictable Buffer objects which are pinned or swapped and as such
+	 * not on an LRU list.
  	 */
-	struct list_head pinned;
+	struct list_head unevictable;
/** 
  	 * @dev_mapping: A pointer to the struct address_space for invalidating
diff --git a/include/drm/ttm/ttm_tt.h b/include/drm/ttm/ttm_tt.h
index 2b9d856ff388..991edafdb2dd 100644
--- a/include/drm/ttm/ttm_tt.h
+++ b/include/drm/ttm/ttm_tt.h
@@ -129,6 +129,11 @@ static inline bool ttm_tt_is_populated(struct ttm_tt *tt)
  	return tt->page_flags & TTM_TT_FLAG_PRIV_POPULATED;
  }
+static inline bool ttm_tt_is_swapped(const struct ttm_tt *tt) 
+{
+	return tt->page_flags & TTM_TT_FLAG_SWAPPED;
+}
+
  /**
   * ttm_tt_create
   *
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