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;
                }
 
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