[PATCH 1/2] [WIP]drm/ttm: add waiter list to prevent allocation not in order

[Chunming Zhou]

there is a scheduling balance issue about get node like:
a. process A allocates full memory and use it for submission.
b. process B tries to allocates memory, will wait for process A BO idle in eviction.
c. process A completes the job, process B eviction will put process A BO node,
but in the meantime, process C is comming to allocate BO, whill directly get node successfully, and do submission,
process B will again wait for process C BO idle.
d. repeat the above setps, process B could be delayed much more.

later allocation must not be ahead of front in same place.

Change-Id: I3daa892e50f82226c552cc008a29e55894a98f18
Signed-off-by: Chunming Zhou <david1.zhou at amd.com>
---
 drivers/gpu/drm/ttm/ttm_bo.c    | 69 +++++++++++++++++++++++++++++++++++++++--
 include/drm/ttm/ttm_bo_api.h    |  7 +++++
 include/drm/ttm/ttm_bo_driver.h |  7 +++++
 3 files changed, 80 insertions(+), 3 deletions(-)

diff --git a/drivers/gpu/drm/ttm/ttm_bo.c b/drivers/gpu/drm/ttm/ttm_bo.c
index d33a6bb742a1..558ec2cf465d 100644
--- a/drivers/gpu/drm/ttm/ttm_bo.c
+++ b/drivers/gpu/drm/ttm/ttm_bo.c
@@ -841,6 +841,58 @@ static int ttm_bo_add_move_fence(struct ttm_buffer_object *bo,
 	return 0;
 }
 
+static void ttm_man_init_waiter(struct ttm_bo_waiter *waiter,
+				struct ttm_buffer_object *bo,
+				const struct ttm_place *place)
+{
+	waiter->tbo = bo;
+	memcpy((void *)&waiter->place, (void *)place, sizeof(*place));
+	INIT_LIST_HEAD(&waiter->list);
+}
+
+static void ttm_man_add_waiter(struct ttm_mem_type_manager *man,
+			       struct ttm_bo_waiter *waiter)
+{
+	if (!waiter)
+		return;
+	spin_lock(&man->wait_lock);
+	list_add_tail(&waiter->list, &man->waiter_list);
+	spin_unlock(&man->wait_lock);
+}
+
+static void ttm_man_del_waiter(struct ttm_mem_type_manager *man,
+			       struct ttm_bo_waiter *waiter)
+{
+	if (!waiter)
+		return;
+	spin_lock(&man->wait_lock);
+	if (!list_empty(&waiter->list))
+		list_del(&waiter->list);
+	spin_unlock(&man->wait_lock);
+	kfree(waiter);
+}
+
+int ttm_man_check_bo(struct ttm_mem_type_manager *man,
+		     struct ttm_buffer_object *bo,
+		     const struct ttm_place *place)
+{
+	struct ttm_bo_waiter *waiter, *tmp;
+
+	spin_lock(&man->wait_lock);
+	list_for_each_entry_safe(waiter, tmp, &man->waiter_list, list) {
+		if ((bo != waiter->tbo) &&
+		    ((place->fpfn >= waiter->place.fpfn &&
+		      place->fpfn <= waiter->place.lpfn) ||
+		     (place->lpfn <= waiter->place.lpfn && place->lpfn >=
+		      waiter->place.fpfn)))
+		    goto later_bo;
+	}
+	spin_unlock(&man->wait_lock);
+	return true;
+later_bo:
+	spin_unlock(&man->wait_lock);
+	return false;
+}
 /**
  * Repeatedly evict memory from the LRU for @mem_type until we create enough
  * space, or we've evicted everything and there isn't enough space.
@@ -853,17 +905,26 @@ static int ttm_bo_mem_force_space(struct ttm_buffer_object *bo,
 {
 	struct ttm_bo_device *bdev = bo->bdev;
 	struct ttm_mem_type_manager *man = &bdev->man[mem_type];
+	struct ttm_bo_waiter waiter;
 	int ret;
 
+	ttm_man_init_waiter(&waiter, bo, place);
+	ttm_man_add_waiter(man, &waiter);
 	do {
 		ret = (*man->func->get_node)(man, bo, place, mem);
-		if (unlikely(ret != 0))
+		if (unlikely(ret != 0)) {
+			ttm_man_del_waiter(man, &waiter);
 			return ret;
-		if (mem->mm_node)
+		}
+		if (mem->mm_node) {
+			ttm_man_del_waiter(man, &waiter);
 			break;
+		}
 		ret = ttm_mem_evict_first(bdev, mem_type, place, ctx);
-		if (unlikely(ret != 0))
+		if (unlikely(ret != 0)) {
+			ttm_man_del_waiter(man, &waiter);
 			return ret;
+		}
 	} while (1);
 	mem->mem_type = mem_type;
 	return ttm_bo_add_move_fence(bo, man, mem);
@@ -1450,6 +1511,8 @@ int ttm_bo_init_mm(struct ttm_bo_device *bdev, unsigned type,
 	man->use_io_reserve_lru = false;
 	mutex_init(&man->io_reserve_mutex);
 	spin_lock_init(&man->move_lock);
+	spin_lock_init(&man->wait_lock);
+	INIT_LIST_HEAD(&man->waiter_list);
 	INIT_LIST_HEAD(&man->io_reserve_lru);
 
 	ret = bdev->driver->init_mem_type(bdev, type, man);
diff --git a/include/drm/ttm/ttm_bo_api.h b/include/drm/ttm/ttm_bo_api.h
index 2cd025c2abe7..0fce4dbd02e7 100644
--- a/include/drm/ttm/ttm_bo_api.h
+++ b/include/drm/ttm/ttm_bo_api.h
@@ -40,6 +40,7 @@
 #include <linux/mm.h>
 #include <linux/bitmap.h>
 #include <linux/reservation.h>
+#include <drm/ttm/ttm_placement.h>
 
 struct ttm_bo_device;
 
@@ -232,6 +233,12 @@ struct ttm_buffer_object {
 	struct mutex wu_mutex;
 };
 
+struct ttm_bo_waiter {
+	struct ttm_buffer_object *tbo;
+	struct ttm_place place;
+	struct list_head list;
+};
+
 /**
  * struct ttm_bo_kmap_obj
  *
diff --git a/include/drm/ttm/ttm_bo_driver.h b/include/drm/ttm/ttm_bo_driver.h
index 9b417eb2df20..dc6b8b4c9e06 100644
--- a/include/drm/ttm/ttm_bo_driver.h
+++ b/include/drm/ttm/ttm_bo_driver.h
@@ -293,6 +293,10 @@ struct ttm_mem_type_manager {
 	bool io_reserve_fastpath;
 	spinlock_t move_lock;
 
+	/* waiters in list */
+	spinlock_t wait_lock;
+	struct list_head waiter_list;
+
 	/*
 	 * Protected by @io_reserve_mutex:
 	 */
@@ -748,6 +752,9 @@ int ttm_bo_mem_space(struct ttm_buffer_object *bo,
 		     struct ttm_mem_reg *mem,
 		     struct ttm_operation_ctx *ctx);
 
+int ttm_man_check_bo(struct ttm_mem_type_manager *man,
+		     struct ttm_buffer_object *bo,
+		     const struct ttm_place *place);
 void ttm_bo_mem_put(struct ttm_buffer_object *bo, struct ttm_mem_reg *mem);
 void ttm_bo_mem_put_locked(struct ttm_buffer_object *bo,
 			   struct ttm_mem_reg *mem);
-- 
2.14.1