svn commit: r190912 - head/sys/vm

[Alan Cox]

Author: alc
Date: Sat Apr 11 09:09:00 2009
New Revision: 190912
URL: http://svn.freebsd.org/changeset/base/190912

Log:
  Previously, when vm_page_free_toq() was performed on a page belonging to
  a reservation, unless all of the reservation's pages were free, the
  reservation was moved to the head of the partially-populated reservations
  queue, where it would be the next reservation to be broken in case the
  free page queues were emptied.  Now, instead, I am moving it to the tail.
  Very likely this reservation is in the process of being freed in its
  entirety, so placing it at the tail of the queue makes it more likely that
  the underlying physical memory will be returned to the free page queues as
  one contiguous chunk.  If a reservation must be broken, it will, instead,
  be the longest unchanged reservation, which is arguably the reservation
  that is least likely to ever achieve promotion or be freed in its entirety.
  
  MFC after:	6 weeks

Modified:
  head/sys/vm/vm_reserv.c

Modified: head/sys/vm/vm_reserv.c
==============================================================================
--- head/sys/vm/vm_reserv.c	Sat Apr 11 08:52:02 2009	(r190911)
+++ head/sys/vm/vm_reserv.c	Sat Apr 11 09:09:00 2009	(r190912)
@@ -138,8 +138,8 @@ static vm_reserv_t vm_reserv_array;
  * The partially-populated reservation queue
  *
  * This queue enables the fast recovery of an unused cached or free small page
- * from a partially-populated reservation.  The head of this queue is either
- * the least-recently-populated or most-recently-depopulated reservation.
+ * from a partially-populated reservation.  The reservation at the head of
+ * this queue is the least-recently-changed, partially-populated reservation.
  *
  * Access to this queue is synchronized by the free page queue lock.
  */
@@ -209,7 +209,7 @@ sysctl_vm_reserv_partpopq(SYSCTL_HANDLER
 /*
  * Reduces the given reservation's population count.  If the population count
  * becomes zero, the reservation is destroyed.  Additionally, moves the
- * reservation to the head of the partially-populated reservations queue if the
+ * reservation to the tail of the partially-populated reservations queue if the
  * population count is non-zero.
  *
  * The free page queue lock must be held.
@@ -235,7 +235,7 @@ vm_reserv_depopulate(vm_reserv_t rv)
 		vm_reserv_freed++;
 	} else {
 		rv->inpartpopq = TRUE;
-		TAILQ_INSERT_HEAD(&vm_rvq_partpop, rv, partpopq);
+		TAILQ_INSERT_TAIL(&vm_rvq_partpop, rv, partpopq);
 	}
 }