[PATCH 2/6] drm/ttm: Use private locks for the default bo range manager

[Thomas Hellstrom]

Searching for a free block in the range manager may in some situations be a
lenghty operation, and we want to avoid holding the global lru lock
during that time. Instead use a per-manager spinlock.

This leaves the global lru lock for quick lru list and swap list manipulation
only, including list manipulation associated with reserving buffer objects.

Signed-off-by: Thomas Hellstrom <thellstrom at vmware.com>
---
 drivers/gpu/drm/ttm/ttm_bo_manager.c |   81 +++++++++++++++++++---------------
 1 files changed, 45 insertions(+), 36 deletions(-)

diff --git a/drivers/gpu/drm/ttm/ttm_bo_manager.c b/drivers/gpu/drm/ttm/ttm_bo_manager.c
index 7410c19..038e947 100644
--- a/drivers/gpu/drm/ttm/ttm_bo_manager.c
+++ b/drivers/gpu/drm/ttm/ttm_bo_manager.c
@@ -1,6 +1,6 @@
 /**************************************************************************
  *
- * Copyright (c) 2007-2009 VMware, Inc., Palo Alto, CA., USA
+ * Copyright (c) 2007-2010 VMware, Inc., Palo Alto, CA., USA
  * All Rights Reserved.
  *
  * Permission is hereby granted, free of charge, to any person obtaining a
@@ -31,20 +31,29 @@
 #include "ttm/ttm_module.h"
 #include "ttm/ttm_bo_driver.h"
 #include "ttm/ttm_placement.h"
-#include <linux/jiffies.h>
+#include "drm_mm.h"
 #include <linux/slab.h>
-#include <linux/sched.h>
-#include <linux/mm.h>
-#include <linux/file.h>
+#include <linux/spinlock.h>
 #include <linux/module.h>
 
+/**
+ * Currently we use a spinlock for the lock, but a mutex *may* be
+ * more appropriate to reduce scheduling latency if the range manager
+ * ends up with very fragmented allocation patterns.
+ */
+
+struct ttm_range_manager {
+	struct drm_mm mm;
+	spinlock_t lock;
+};
+
 static int ttm_bo_man_get_node(struct ttm_mem_type_manager *man,
 			       struct ttm_buffer_object *bo,
 			       struct ttm_placement *placement,
 			       struct ttm_mem_reg *mem)
 {
-	struct ttm_bo_global *glob = man->bdev->glob;
-	struct drm_mm *mm = man->priv;
+	struct ttm_range_manager *rman = (struct ttm_range_manager *) man->priv;
+	struct drm_mm *mm = &rman->mm;
 	struct drm_mm_node *node = NULL;
 	unsigned long lpfn;
 	int ret;
@@ -57,19 +66,19 @@ static int ttm_bo_man_get_node(struct ttm_mem_type_manager *man,
 		if (unlikely(ret))
 			return ret;
 
-		spin_lock(&glob->lru_lock);
+		spin_lock(&rman->lock);
 		node = drm_mm_search_free_in_range(mm,
 					mem->num_pages, mem->page_alignment,
 					placement->fpfn, lpfn, 1);
 		if (unlikely(node == NULL)) {
-			spin_unlock(&glob->lru_lock);
+			spin_unlock(&rman->lock);
 			return 0;
 		}
 		node = drm_mm_get_block_atomic_range(node, mem->num_pages,
-							mem->page_alignment,
-							placement->fpfn,
-							lpfn);
-		spin_unlock(&glob->lru_lock);
+						     mem->page_alignment,
+						     placement->fpfn,
+						     lpfn);
+		spin_unlock(&rman->lock);
 	} while (node == NULL);
 
 	mem->mm_node = node;
@@ -80,12 +89,12 @@ static int ttm_bo_man_get_node(struct ttm_mem_type_manager *man,
 static void ttm_bo_man_put_node(struct ttm_mem_type_manager *man,
 				struct ttm_mem_reg *mem)
 {
-	struct ttm_bo_global *glob = man->bdev->glob;
+	struct ttm_range_manager *rman = (struct ttm_range_manager *) man->priv;
 
 	if (mem->mm_node) {
-		spin_lock(&glob->lru_lock);
+		spin_lock(&rman->lock);
 		drm_mm_put_block(mem->mm_node);
-		spin_unlock(&glob->lru_lock);
+		spin_unlock(&rman->lock);
 		mem->mm_node = NULL;
 	}
 }
@@ -93,49 +102,49 @@ static void ttm_bo_man_put_node(struct ttm_mem_type_manager *man,
 static int ttm_bo_man_init(struct ttm_mem_type_manager *man,
 			   unsigned long p_size)
 {
-	struct drm_mm *mm;
+	struct ttm_range_manager *rman;
 	int ret;
 
-	mm = kzalloc(sizeof(*mm), GFP_KERNEL);
-	if (!mm)
+	rman = kzalloc(sizeof(*rman), GFP_KERNEL);
+	if (!rman)
 		return -ENOMEM;
 
-	ret = drm_mm_init(mm, 0, p_size);
+	ret = drm_mm_init(&rman->mm, 0, p_size);
 	if (ret) {
-		kfree(mm);
+		kfree(rman);
 		return ret;
 	}
 
-	man->priv = mm;
+	spin_lock_init(&rman->lock);
+	man->priv = rman;
 	return 0;
 }
 
 static int ttm_bo_man_takedown(struct ttm_mem_type_manager *man)
 {
-	struct ttm_bo_global *glob = man->bdev->glob;
-	struct drm_mm *mm = man->priv;
-	int ret = 0;
+	struct ttm_range_manager *rman = (struct ttm_range_manager *) man->priv;
+	struct drm_mm *mm = &rman->mm;
 
-	spin_lock(&glob->lru_lock);
+	spin_lock(&rman->lock);
 	if (drm_mm_clean(mm)) {
 		drm_mm_takedown(mm);
-		kfree(mm);
+		spin_unlock(&rman->lock);
+		kfree(rman);
 		man->priv = NULL;
-	} else
-		ret = -EBUSY;
-	spin_unlock(&glob->lru_lock);
-	return ret;
+		return 0;
+	}
+	spin_unlock(&rman->lock);
+	return -EBUSY;
 }
 
 static void ttm_bo_man_debug(struct ttm_mem_type_manager *man,
 			     const char *prefix)
 {
-	struct ttm_bo_global *glob = man->bdev->glob;
-	struct drm_mm *mm = man->priv;
+	struct ttm_range_manager *rman = (struct ttm_range_manager *) man->priv;
 
-	spin_lock(&glob->lru_lock);
-	drm_mm_debug_table(mm, prefix);
-	spin_unlock(&glob->lru_lock);
+	spin_lock(&rman->lock);
+	drm_mm_debug_table(&rman->mm, prefix);
+	spin_unlock(&rman->lock);
 }
 
 const struct ttm_mem_type_manager_func ttm_bo_manager_func = {
-- 
1.6.2.5