svn commit: r249278 - head/sys/vm

[Attilio Rao]

Author: attilio
Date: Mon Apr  8 20:02:27 2013
New Revision: 249278
URL: http://svnweb.freebsd.org/changeset/base/249278

Log:
  The per-page act_count can be made very-easily protected by the
  per-page lock rather than vm_object lock, without any further overhead.
  Make the formal switch.
  
  Sponsored by:	EMC / Isilon storage division
  Reviewed by:	alc
  Tested by:	pho

Modified:
  head/sys/vm/vm_page.h
  head/sys/vm/vm_pageout.c

Modified: head/sys/vm/vm_page.h
==============================================================================
--- head/sys/vm/vm_page.h	Mon Apr  8 19:58:32 2013	(r249277)
+++ head/sys/vm/vm_page.h	Mon Apr  8 20:02:27 2013	(r249278)
@@ -143,7 +143,7 @@ struct vm_page {
 	uint8_t aflags;			/* access is atomic */
 	uint8_t oflags;			/* page VPO_* flags (O) */
 	uint16_t flags;			/* page PG_* flags (P) */
-	u_char	act_count;		/* page usage count (O) */
+	u_char	act_count;		/* page usage count (P) */
 	u_char	busy;			/* page busy count (O) */
 	/* NOTE that these must support one bit per DEV_BSIZE in a page!!! */
 	/* so, on normal X86 kernels, they must be at least 8 bits wide */

Modified: head/sys/vm/vm_pageout.c
==============================================================================
--- head/sys/vm/vm_pageout.c	Mon Apr  8 19:58:32 2013	(r249277)
+++ head/sys/vm/vm_pageout.c	Mon Apr  8 20:02:27 2013	(r249278)
@@ -1015,9 +1015,9 @@ vm_pageout_scan(int pass)
 		} else if ((m->aflags & PGA_REFERENCED) == 0 &&
 		    (actcount = pmap_ts_referenced(m)) != 0) {
 			vm_page_activate(m);
-			vm_page_unlock(m);
-			m->act_count += actcount + ACT_ADVANCE;
 			VM_OBJECT_WUNLOCK(object);
+			m->act_count += actcount + ACT_ADVANCE;
+			vm_page_unlock(m);
 			goto relock_queues;
 		}
 
@@ -1031,9 +1031,9 @@ vm_pageout_scan(int pass)
 			vm_page_aflag_clear(m, PGA_REFERENCED);
 			actcount = pmap_ts_referenced(m);
 			vm_page_activate(m);
-			vm_page_unlock(m);
-			m->act_count += actcount + ACT_ADVANCE + 1;
 			VM_OBJECT_WUNLOCK(object);
+			m->act_count += actcount + ACT_ADVANCE + 1;
+			vm_page_unlock(m);
 			goto relock_queues;
 		}