PERFORCE change 200662 for review

[John Baldwin]

http://p4web.freebsd.org/@@200662?ac=10

Change 200662 by jhb at jhb_jhbbsd on 2011/10/24 18:40:59

	Add a vm_object_page_cache() method which attempts to move clean
	pages into the cache queue.

Affected files ...

.. //depot/projects/fadvise/sys/vm/vm_object.c#2 edit
.. //depot/projects/fadvise/sys/vm/vm_object.h#2 edit

Differences ...

==== //depot/projects/fadvise/sys/vm/vm_object.c#2 (text+ko) ====

@@ -1863,6 +1863,50 @@
 }
 
 /*
+ *	vm_object_page_cache:
+ *
+ *	For the given object, attempt to move the specified clean
+ *	pages to the cache queue.  If a page is wired for any reason,
+ *	then it will not be changed.  Pages are specified by the given
+ *	range ["start", "end").  As a special case, if "end" is zero,
+ *	then the range extends from "start" to the end of the object.
+ *	Any mappings to the specified pages are removed before the
+ *	pages are moved to the cache queue.
+ *
+ *	This operation should only be performed on objects that
+ *	contain managed pages.
+ *
+ *	The object must be locked.
+ */
+void
+vm_object_page_cache(vm_object_t object, vm_pindex_t start, vm_pindex_t end)
+{
+	vm_page_t p, next;
+
+	VM_OBJECT_LOCK_ASSERT(object, MA_OWNED);
+	KASSERT((object->type != OBJT_DEVICE && object->type != OBJT_SG &&
+	    object->type != OBJT_PHYS),
+	    ("vm_object_page_cache: illegal object %p", object));
+	if (object->resident_page_count == 0)
+		return;
+	vm_object_pip_add(object, 1);
+	p = vm_page_find_least(object, start);
+
+	/*
+	 * Here, the variable "p" is either (1) the page with the least pindex
+	 * greater than or equal to the parameter "start" or (2) NULL. 
+	 */
+	for (; p != NULL && (p->pindex < end || end == 0); p = next) {
+		next = TAILQ_NEXT(p, listq);
+
+		vm_page_lock(p);
+		vm_page_try_to_cache(p);
+		vm_page_unlock(p);
+	}
+	vm_object_pip_wakeup(object);
+}
+
+/*
  *	Populate the specified range of the object with valid pages.  Returns
  *	TRUE if the range is successfully populated and FALSE otherwise.
  *

==== //depot/projects/fadvise/sys/vm/vm_object.h#2 (text+ko) ====

@@ -223,6 +223,8 @@
 void vm_object_terminate (vm_object_t);
 void vm_object_set_writeable_dirty (vm_object_t);
 void vm_object_init (void);
+void vm_object_page_cache(vm_object_t object, vm_pindex_t start,
+    vm_pindex_t end);
 void vm_object_page_clean(vm_object_t object, vm_ooffset_t start,
     vm_ooffset_t end, int flags);
 void vm_object_page_remove(vm_object_t object, vm_pindex_t start,