Reduce the scope of the page queues lock and the number of

PG_REFERENCED changes in vm_pageout_object_deactivate_pages().
Simplify this function's inner loop using TAILQ_FOREACH(), and shorten
some of its overly long lines.  Update a stale comment.

Assert that PG_REFERENCED may be cleared only if the object containing
the page is locked.  Add a comment documenting this.

Assert that a caller to vm_page_requeue() holds the page queues lock,
and assert that the page is on a page queue.

Push down the page queues lock into pmap_ts_referenced() and
pmap_page_exists_quick().  (As of now, there are no longer any pmap
functions that expect to be called with the page queues lock held.)

Neither pmap_ts_referenced() nor pmap_page_exists_quick() should ever
be passed an unmanaged page.  Assert this rather than returning "0"
and "FALSE" respectively.

ARM:

Simplify pmap_page_exists_quick() by switching to TAILQ_FOREACH().

Push down the page queues lock inside of pmap_clearbit(), simplifying
pmap_clear_modify(), pmap_clear_reference(), and pmap_remove_write().
Additionally, this allows for avoiding the acquisition of the page
queues lock in some cases.

PowerPC/AIM:

moea*_page_exits_quick() and moea*_page_wired_mappings() will never be
called before pmap initialization is complete.  Therefore, the check
for moea_initialized can be eliminated.

Push down the page queues lock inside of moea*_clear_bit(),
simplifying moea*_clear_modify() and moea*_clear_reference().

The last parameter to moea*_clear_bit() is never used.  Eliminate it.

PowerPC/BookE:

Simplify mmu_booke_page_exists_quick()'s control flow.

Reviewed by:	kib@

1 files changed, 3 insertions, 0 deletions

diff --git a/sys/vm/vm_page.h b/sys/vm/vm_page.h
index e8f68d2..3133ee4 100644
--- a/sys/vm/vm_page.h
+++ b/sys/vm/vm_page.h
@@ -219,6 +219,9 @@ extern struct vpglocks pa_lock[];
  *	 pte mappings, nor can they be removed from their objects via 
  *	 the object, and such pages are also not on any PQ queue.
  *
+ * PG_REFERENCED may be cleared only if the object containing the page is
+ * locked.
+ *
  * PG_WRITEABLE is set exclusively on managed pages by pmap_enter().  When it
  * does so, the page must be VPO_BUSY.
  */