svn commit: r284387 - head/sys/vm

[Konstantin Belousov]

Author: kib
Date: Sun Jun 14 20:23:41 2015
New Revision: 284387
URL: https://svnweb.freebsd.org/changeset/base/284387

Log:
  Invalid pages do not need neither update of the activation count nor
  they coould be dirty.  Move the handling if the invalid pages in the
  inactive scan earlier.
  
  Remove some code duplication in the scan by introducing the
  'drop_page' label, which centralizes the object and the page unlock.
  
  Suggested and reviewed by:	alc
  Sponsored by:	The FreeBSD Foundation
  MFC after:	2 weeks

Modified:
  head/sys/vm/vm_pageout.c

Modified: head/sys/vm/vm_pageout.c
==============================================================================
--- head/sys/vm/vm_pageout.c	Sun Jun 14 20:16:36 2015	(r284386)
+++ head/sys/vm/vm_pageout.c	Sun Jun 14 20:23:41 2015	(r284387)
@@ -1159,6 +1159,17 @@ vm_pageout_scan(struct vm_domain *vmd, i
 		queues_locked = FALSE;
 
 		/*
+		 * Invalid pages can be easily freed. They cannot be
+		 * mapped, vm_page_free() asserts this.
+		 */
+		if (m->valid == 0 && m->hold_count == 0) {
+			vm_page_free(m);
+			PCPU_INC(cnt.v_dfree);
+			--page_shortage;
+			goto drop_page;
+		}
+
+		/*
 		 * We bump the activation count if the page has been
 		 * referenced while in the inactive queue.  This makes
 		 * it less likely that the page will be added back to the
@@ -1192,15 +1203,10 @@ vm_pageout_scan(struct vm_domain *vmd, i
 				queues_locked = TRUE;
 				vm_page_requeue_locked(m);
 			}
-			VM_OBJECT_WUNLOCK(object);
-			vm_page_unlock(m);
-			goto relock_queues;
+			goto drop_page;
 		}
 
 		if (m->hold_count != 0) {
-			vm_page_unlock(m);
-			VM_OBJECT_WUNLOCK(object);
-
 			/*
 			 * Held pages are essentially stuck in the
 			 * queue.  So, they ought to be discounted
@@ -1209,7 +1215,7 @@ vm_pageout_scan(struct vm_domain *vmd, i
 			 * loop over the active queue below.
 			 */
 			addl_page_shortage++;
-			goto relock_queues;
+			goto drop_page;
 		}
 
 		/*
@@ -1224,14 +1230,7 @@ vm_pageout_scan(struct vm_domain *vmd, i
 		if (m->dirty == 0 && object->ref_count != 0)
 			pmap_remove_all(m);
 
-		if (m->valid == 0) {
-			/*
-			 * Invalid pages can be easily freed
-			 */
-			vm_page_free(m);
-			PCPU_INC(cnt.v_dfree);
-			--page_shortage;
-		} else if (m->dirty == 0) {
+		if (m->dirty == 0) {
 			/*
 			 * Clean pages can be freed.
 			 */
@@ -1305,6 +1304,7 @@ vm_pageout_scan(struct vm_domain *vmd, i
 			vm_page_lock_assert(m, MA_NOTOWNED);
 			goto relock_queues;
 		}
+drop_page:
 		vm_page_unlock(m);
 		VM_OBJECT_WUNLOCK(object);
 relock_queues: