vm_page no longer points directly to its containing cache, but rather to a

VMCacheRef object which points to the cache. This allows to optimize
VMCache::MoveAllPages(), since it no longer needs to iterate over all pages
to adjust their cache pointer. It can simple swap the cache refs of the two
caches instead.

Reduces the total -j8 Haiku image build time only marginally. The kernel time
drops almost 10%, though.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@35155 a95241bf-73f2-0310-859d-f6bbb57e9c96

headers/private/kernel/vm/VMCache.h

@@ -61,6 +61,7 @@ struct VMCachePagesTreeDefinition {
 
 typedef IteratableSplayTree<VMCachePagesTreeDefinition> VMCachePagesTree;
 
+
 struct VMCache {
 public:
 								VMCache();
@@ -171,6 +172,7 @@ public:
 
 private:
 			struct PageEventWaiter;
+			friend struct VMCacheRef;
 
 private:
 			void				_NotifyPageEvents(vm_page* page, uint32 events);
@@ -185,6 +187,7 @@ private:
 			mutex				fLock;
 			PageEventWaiter*	fPageEventWaiters;
 			void*				fUserData;
+			VMCacheRef*			fCacheRef;
 };
 
 

headers/private/kernel/vm/vm_types.h

@@ -26,6 +26,7 @@
 class AsyncIOCallback;
 struct vm_page_mapping;
 struct VMCache;
+struct VMCacheRef;
 typedef DoublyLinkedListLink<vm_page_mapping> vm_page_mapping_link;
 
 
@@ -71,12 +72,23 @@ typedef class DoublyLinkedQueue<vm_page_mapping, DoublyLinkedAreaLink>
 
 typedef uint32 page_num_t;
 
+
+struct VMCacheRef {
+			VMCache*			cache;
+			int32				ref_count;
+
+								VMCacheRef(VMCache* cache);
+};
+
+
 struct vm_page {
 	DoublyLinkedListLink<vm_page> queue_link;
 
 	addr_t					physical_page_number;
 
-	VMCache*				cache;
+private:
+	VMCacheRef*				cache_ref;
+public:
 	page_num_t				cache_offset;
 								// in page size units
 
@@ -103,6 +115,13 @@ struct vm_page {
 
 	int8					usage_count;
 	uint16					wired_count;
+
+
+	VMCacheRef* CacheRef() const			{ return cache_ref; }
+	void SetCacheRef(VMCacheRef* cacheRef)	{ this->cache_ref = cacheRef; }
+
+	VMCache* Cache() const
+		{ return cache_ref != NULL ? cache_ref->cache : NULL; }
 };