Initial support for MADV_FREE, support for pages that we don't care

about the contents anymore.  This gives us alot of the advantage of
freeing individual pages through munmap, but with almost none of the
overhead.

4 files changed, 43 insertions, 59 deletions

diff --git a/sys/vm/swap_pager.c b/sys/vm/swap_pager.c
index 4feebd5..37427ec 100644
--- a/sys/vm/swap_pager.c
+++ b/sys/vm/swap_pager.c
@@ -39,7 +39,7 @@
  * from: Utah $Hdr: swap_pager.c 1.4 91/04/30$
  *
  *	@(#)swap_pager.c	8.9 (Berkeley) 3/21/94
- * $Id: swap_pager.c,v 1.65 1996/05/03 21:01:47 phk Exp $
+ * $Id: swap_pager.c,v 1.66 1996/05/18 03:37:32 dyson Exp $
  */
 
 /*
@@ -438,6 +438,32 @@ swap_pager_freespace(object, start, size)
 	splx(s);
 }
 
+/*
+ * same as freespace, but don't free, just force a DMZ next time
+ */
+void
+swap_pager_dmzspace(object, start, size)
+	vm_object_t object;
+	vm_pindex_t start;
+	vm_size_t size;
+{
+	vm_pindex_t i;
+	int s;
+
+	s = splbio();
+	for (i = start; i < start + size; i += 1) {
+		int valid;
+		daddr_t *addr = swap_pager_diskaddr(object, i, &valid);
+
+		if (addr && *addr != SWB_EMPTY) {
+			if (valid) {
+				swap_pager_setvalid(object, i, 0);
+			}
+		}
+	}
+	splx(s);
+}
+
 static void
 swap_pager_free_swap(object)
 	vm_object_t object;
diff --git a/sys/vm/swap_pager.h b/sys/vm/swap_pager.h
index 3fdd44e..5240eb5 100644
--- a/sys/vm/swap_pager.h
+++ b/sys/vm/swap_pager.h
@@ -36,7 +36,7 @@
  * SUCH DAMAGE.
  *
  *	from: @(#)swap_pager.h	7.1 (Berkeley) 12/5/90
- *	$Id: swap_pager.h,v 1.14 1996/01/30 23:02:29 mpp Exp $
+ *	$Id: swap_pager.h,v 1.15 1996/03/03 21:11:06 dyson Exp $
  */
 
 /*
@@ -73,6 +73,7 @@ int swap_pager_swp_alloc __P((vm_object_t, int));
 void swap_pager_copy __P((vm_object_t, vm_pindex_t, vm_object_t,
 	vm_pindex_t, vm_pindex_t));
 void swap_pager_freespace __P((vm_object_t, vm_pindex_t, vm_size_t));
+void swap_pager_dmzspace __P((vm_object_t, vm_pindex_t, vm_size_t));
 void swap_pager_swap_init __P((void));
 #endif
 
diff --git a/sys/vm/vm_map.c b/sys/vm/vm_map.c
index 89f4e87..f0339e8 100644
--- a/sys/vm/vm_map.c
+++ b/sys/vm/vm_map.c
@@ -61,7 +61,7 @@
  * any improvements or extensions that they make and grant Carnegie the
  * rights to redistribute these changes.
  *
- * $Id: vm_map.c,v 1.45 1996/05/18 03:37:43 dyson Exp $
+ * $Id: vm_map.c,v 1.46 1996/05/19 07:36:46 dyson Exp $
  */
 
 /*
@@ -1225,6 +1225,7 @@ vm_map_madvise(map, pmap, start, end, advise)
 	 * Right now, we could handle DONTNEED and WILLNEED with common code.
 	 * They are mostly the same, except for the potential async reads (NYI).
 	 */
+	case MADV_FREE:
 	case MADV_DONTNEED:
 			{
 				vm_pindex_t pindex;
diff --git a/sys/vm/vm_object.c b/sys/vm/vm_object.c
index 83ee0cd..da2c62c 100644
--- a/sys/vm/vm_object.c
+++ b/sys/vm/vm_object.c
@@ -61,7 +61,7 @@
  * any improvements or extensions that they make and grant Carnegie the
  * rights to redistribute these changes.
  *
- * $Id: vm_object.c,v 1.71 1996/05/21 05:26:27 dyson Exp $
+ * $Id: vm_object.c,v 1.72 1996/05/21 17:13:31 dyson Exp $
  */
 
 /*
@@ -709,7 +709,9 @@ vm_object_madvise(object, pindex, count, advise)
 		if (advise == MADV_WILLNEED) {
 			if (m->queue != PQ_ACTIVE)
 				vm_page_activate(m);
-		} else if (advise == MADV_DONTNEED) {
+		} else if ((advise == MADV_DONTNEED) ||
+			((advise == MADV_FREE) &&
+				((object->type != OBJT_DEFAULT) && (object->type != OBJT_SWAP)))) {
 			/*
 			 * If the upper level VM system doesn't think that
 			 * the page is dirty, check the pmap layer.
@@ -732,65 +734,19 @@ vm_object_madvise(object, pindex, count, advise)
 				vm_page_protect(m, VM_PROT_NONE);
 				vm_page_deactivate(m);
 			}
+		} else if (advise == MADV_FREE) {
+			/*
+			 * Force a demand-zero on next ref
+			 */
+			if (object->type == OBJT_SWAP)
+				swap_pager_dmzspace(object, m->pindex, 1);
+			vm_page_protect(m, VM_PROT_NONE);
+			vm_page_free(m);
 		}
 	}	
 }
 
 /*
- *	vm_object_copy:
- *
- *	Create a new object which is a copy of an existing
- *	object, and mark all of the pages in the existing
- *	object 'copy-on-write'.  The new object has one reference.
- *	Returns the new object.
- *
- *	May defer the copy until later if the object is not backed
- *	up by a non-default pager.
- *
- */
-void
-vm_object_copy(src_object, src_offset,
-    dst_object, dst_offset, src_needs_copy)
-	register vm_object_t src_object;
-	vm_pindex_t src_offset;
-	vm_object_t *dst_object;/* OUT */
-	vm_pindex_t *dst_offset;/* OUT */
-	boolean_t *src_needs_copy;	/* OUT */
-{
-	if (src_object == NULL) {
-		/*
-		 * Nothing to copy
-		 */
-		*dst_object = NULL;
-		*dst_offset = 0;
-		*src_needs_copy = FALSE;
-		return;
-	}
-
-	/*
-	 * Try to collapse the object before copying it.
-	 */
-	if (src_object->handle == NULL &&
-	    (src_object->type == OBJT_DEFAULT ||
-	     src_object->type == OBJT_SWAP))
-		vm_object_collapse(src_object);
-
-
-	/*
-	 * Make another reference to the object
-	 */
-	src_object->ref_count++;
-	*dst_object = src_object;
-	*dst_offset = src_offset;
-
-	/*
-	 * Must make a shadow when write is desired
-	 */
-	*src_needs_copy = TRUE;
-	return;
-}
-
-/*
  *	vm_object_shadow:
  *
  *	Create a new object which is backed by the