Fix a problem with the pageout daemon RSS limiting, where it degrades

performance to LRU or worse when RSS limiting takes effect.  Also,
make an end condition in the active queue scan more efficient in the
case where pages are removed from the active queue as a side effect
of a pmap operation.

1 files changed, 27 insertions, 21 deletions

diff --git a/sys/vm/vm_pageout.c b/sys/vm/vm_pageout.c
index 558d2b6cf3b5..6a13ec88570d 100644
--- a/sys/vm/vm_pageout.c
+++ b/sys/vm/vm_pageout.c
@@ -65,7 +65,7 @@
  * any improvements or extensions that they make and grant Carnegie the
  * rights to redistribute these changes.
  *
- * $Id: vm_pageout.c,v 1.79 1996/06/26 05:39:26 dyson Exp $
+ * $Id: vm_pageout.c,v 1.80 1996/06/29 09:15:39 davidg Exp $
  */
 
 /*
@@ -446,30 +446,30 @@ vm_pageout_object_deactivate_pages(map, object, desired, map_remove_only)
 				continue;
 			}
 
-			if ((p->flags & PG_REFERENCED) == 0) {
-				refcount = pmap_ts_referenced(VM_PAGE_TO_PHYS(p));
-				if (refcount) {
-					p->act_count += refcount - 1;
-					p->flags |= PG_REFERENCED;
-				}
-			} else {
-				pmap_clear_reference(VM_PAGE_TO_PHYS(p));
+			refcount = pmap_ts_referenced(VM_PAGE_TO_PHYS(p));
+			if (refcount) {
+				p->flags |= PG_REFERENCED;
+			} else if (p->flags & PG_REFERENCED) {
+				refcount = 1;
 			}
 
 			if ((p->queue != PQ_ACTIVE) &&
 				(p->flags & PG_REFERENCED)) {
 				vm_page_activate(p);
-			}
-
-			/*
-			 * if a page is active, not wired and is in the processes
-			 * pmap, then deactivate the page.
-			 */
-			if (p->queue == PQ_ACTIVE) {
+				p->act_count += refcount;
+				p->flags &= ~PG_REFERENCED;
+			} else if (p->queue == PQ_ACTIVE) {
 				if ((p->flags & PG_REFERENCED) == 0) {
-					vm_page_protect(p, VM_PROT_NONE);
-					if (!remove_mode)
+					p->act_count -= min(p->act_count, ACT_DECLINE);
+					if (!remove_mode && (vm_pageout_algorithm_lru || (p->act_count == 0))) {
+						vm_page_protect(p, VM_PROT_NONE);
 						vm_page_deactivate(p);
+					} else {
+						s = splvm();
+						TAILQ_REMOVE(&vm_page_queue_active, p, pageq);
+						TAILQ_INSERT_TAIL(&vm_page_queue_active, p, pageq);
+						splx(s);
+					}
 				} else {
 					p->flags &= ~PG_REFERENCED;
 					if (p->act_count < (ACT_MAX - ACT_ADVANCE))
@@ -564,7 +564,7 @@ vm_pageout_map_deactivate_pages(map, desired)
 static int
 vm_pageout_scan()
 {
-	vm_page_t m, next;
+	vm_page_t m, next, nextnext;
 	int page_shortage, addl_page_shortage, maxscan, maxlaunder, pcount;
 	int pages_freed;
 	struct proc *p, *bigproc;
@@ -753,17 +753,23 @@ rescan0:
 		page_shortage += addl_page_shortage;
 	}
 
-
 	pcount = cnt.v_active_count;
 	m = TAILQ_FIRST(&vm_page_queue_active);
+	nextnext = NULL;
 	while ((m != NULL) && (pcount-- > 0) && (page_shortage > 0)) {
 		int refcount;
 
 		if (m->queue != PQ_ACTIVE) {
-			break;
+			m = nextnext;
+			if ((m == NULL) || (m->queue != PQ_ACTIVE))
+				break;
 		}
 
 		next = TAILQ_NEXT(m, pageq);
+		if (next)
+			nextnext = TAILQ_NEXT(next, pageq);
+		else
+			nextnext = NULL;
 
 		/*
 		 * Don't deactivate pages that are busy.