Patch by Zhao Shuai with changes by myself:

* Init swap support in main().
* Added "bool swappable" parameter to
  VMCacheFactory::CreateAnonymousCache(). A cache supporting swapping
  is created when true. Adjusted invocations accordingly.
* The page writer does now write non-locked swappable pages (when
  memory is low).
* Fixed header guard of VMAnonymousNoSwapCache.h.
* Swap support is compiled conditionally, controlled by the
  ENABLE_SWAP_SUPPORT in src/system/kernel/vm/VMAnonymousCache.h. It is
  disabled ATM. Since no swap files are added, it wouldn't have much
  effect anyway.


git-svn-id: file:///srv/svn/repos/haiku/haiku/trunk@26625 a95241bf-73f2-0310-859d-f6bbb57e9c96

src/system/kernel/main.cpp

@@ -50,6 +50,8 @@
 
 #include <string.h>
 
+#include "vm/VMAnonymousCache.h"
+
 
 //#define TRACE_BOOT
 #ifdef TRACE_BOOT
@@ -185,6 +187,10 @@ _start(kernel_args *bootKernelArgs, int currentCPU)
 		notifications_init();
 		TRACE("init VFS\n");
 		vfs_init(&sKernelArgs);
+#if ENABLE_SWAP_SUPPORT
+		TRACE("init swap support\n");
+		swap_init();
+#endif
 
 		// bring up the AP cpus in a lock step fashion
 		TRACE("waking up AP cpus\n");

src/system/kernel/vm/VMAnonymousCache.cpp

@@ -22,6 +22,9 @@
 #include <util/DoublyLinkedList.h>
 #include <util/OpenHashTable.h>
 
+
+#if	ENABLE_SWAP_SUPPORT
+
 //#define TRACE_STORE
 #ifdef TRACE_STORE
 #	define TRACE(x) dprintf x
@@ -725,3 +728,5 @@ swap_init(void)
 	sAvailSwapSpace = 0;
 }
 
+#endif	// ENABLE_SWAP_SUPPORT
+

src/system/kernel/vm/VMAnonymousCache.h

@@ -12,6 +12,12 @@
 #include <vm_types.h>
 
 
+// uncomment to build in swap support
+//#define ENABLE_SWAP_SUPPORT 1
+
+#if ENABLE_SWAP_SUPPORT
+
+
 typedef page_num_t swap_addr_t;
 struct swap_block;
 
@@ -49,4 +55,8 @@ private:
 };
 
 
+extern "C" void swap_init(void);
+
+#endif	// ENABLE_SWAP_SUPPORT
+
 #endif	/* _KERNEL_VM_STORE_ANONYMOUS_H */

src/system/kernel/vm/VMAnonymousNoSwapCache.h

@@ -6,8 +6,8 @@
  * Copyright 2001-2002, Travis Geiselbrecht. All rights reserved.
  * Distributed under the terms of the NewOS License.
  */
-#ifndef _KERNEL_VM_STORE_ANONYMOUS_H
-#define _KERNEL_VM_STORE_ANONYMOUS_H
+#ifndef _KERNEL_VM_STORE_ANONYMOUS_NO_SWAP_H
+#define _KERNEL_VM_STORE_ANONYMOUS_NO_SWAP_H
 
 #include <vm_types.h>
 
@@ -39,4 +39,4 @@ private:
 };
 
 
-#endif	/* _KERNEL_VM_STORE_ANONYMOUS_H */
+#endif	/* _KERNEL_VM_STORE_ANONYMOUS_NO_SWAP_H */

src/system/kernel/vm/vm.cpp

@@ -1401,7 +1401,7 @@ map_backing_store(vm_address_space *addressSpace, vm_cache *cache,
 
 		// create an anonymous cache
 		status = VMCacheFactory::CreateAnonymousCache(newCache,
-			(protection & B_STACK_AREA) != 0, 0, USER_STACK_GUARD_PAGES);
+			(protection & B_STACK_AREA) != 0, 0, USER_STACK_GUARD_PAGES, true);
 		if (status != B_OK)
 			goto err1;
 
@@ -1639,7 +1639,8 @@ vm_create_anonymous_area(team_id team, const char *name, void **address,
 	status = VMCacheFactory::CreateAnonymousCache(cache,
 		canOvercommit, isStack ? 2 : 0,
 		isStack ? ((protection & B_USER_PROTECTION) != 0 ?
-			USER_STACK_GUARD_PAGES : KERNEL_STACK_GUARD_PAGES) : 0);
+			USER_STACK_GUARD_PAGES : KERNEL_STACK_GUARD_PAGES) : 0,
+		wiring == B_NO_LOCK);
 	if (status != B_OK)
 		goto err1;
 
@@ -2302,7 +2303,7 @@ vm_copy_on_write_area(vm_cache* lowerCache)
 
 	// create an anonymous cache
 	status_t status = VMCacheFactory::CreateAnonymousCache(upperCache, false, 0,
-		0);
+		0, true);
 	if (status != B_OK)
 		return status;
 

src/system/kernel/vm/vm_cache.cpp

@@ -961,6 +961,7 @@ VMCache::_RemoveConsumer(VMCache* consumer)
 
 #include <heap.h>
 
+#include "VMAnonymousCache.h"
 #include "VMAnonymousNoSwapCache.h"
 #include "VMDeviceCache.h"
 #include "VMNullCache.h"
@@ -969,8 +970,28 @@ VMCache::_RemoveConsumer(VMCache* consumer)
 
 /*static*/ status_t
 VMCacheFactory::CreateAnonymousCache(VMCache*& _cache, bool canOvercommit,
-	int32 numPrecommittedPages, int32 numGuardPages)
+	int32 numPrecommittedPages, int32 numGuardPages, bool swappable)
 {
+#if ENABLE_SWAP_SUPPORT
+	if (swappable) {
+		VMAnonymousCache* cache = new(nogrow) VMAnonymousCache;
+		if (cache == NULL)
+			return B_NO_MEMORY;
+
+		status_t error = cache->Init(canOvercommit, numPrecommittedPages,
+			numGuardPages);
+		if (error != B_OK) {
+			cache->Delete();
+			return error;
+		}
+
+		T(Create(cache));
+
+		_cache = cache;
+		return B_OK;
+	}
+#endif
+
 	VMAnonymousNoSwapCache* cache = new(nogrow) VMAnonymousNoSwapCache;
 	if (cache == NULL)
 		return B_NO_MEMORY;

src/system/kernel/vm/vm_page.cpp

@@ -989,10 +989,16 @@ page_writer(void* /*unused*/)
 				continue;
 
 			vm_cache *cache = page->cache;
-			// TODO: write back temporary ones as soon as we have swap file support
-			if (cache->temporary
-				/*&& low_resource_state(B_KERNEL_RESOURCE_PAGES)
-					== B_NO_LOW_RESOURCE*/) {
+
+			// Don't write back wired (locked) pages and don't write RAM pages
+			// until we're low on pages.
+			if (page->wired_count > 0
+#if ENABLE_SWAP_SUPPORT
+				|| cache->temporary
+					&& low_resource_state(B_KERNEL_RESOURCE_PAGES)
+							== B_NO_LOW_RESOURCE
+#endif
+				) {
 				continue;
 			}