svn commit: r208657 - in head/sys: amd64/amd64 i386/i386 i386/xen

[Alan Cox]

Author: alc
Date: Sun May 30 18:48:41 2010
New Revision: 208657
URL: http://svn.freebsd.org/changeset/base/208657

Log:
  Simplify the inner loop of pmap_collect(): While iterating over the page's
  pv list, there is no point in checking whether or not the pv list is empty.
  Instead, wait until the loop completes.

Modified:
  head/sys/amd64/amd64/pmap.c
  head/sys/i386/i386/pmap.c
  head/sys/i386/xen/pmap.c

Modified: head/sys/amd64/amd64/pmap.c
==============================================================================
--- head/sys/amd64/amd64/pmap.c	Sun May 30 14:20:32 2010	(r208656)
+++ head/sys/amd64/amd64/pmap.c	Sun May 30 18:48:41 2010	(r208657)
@@ -2041,7 +2041,6 @@ SYSCTL_INT(_vm_pmap, OID_AUTO, pmap_coll
 static void
 pmap_collect(pmap_t locked_pmap, struct vpgqueues *vpq)
 {
-	struct md_page *pvh;
 	pd_entry_t *pde;
 	pmap_t pmap;
 	pt_entry_t *pte, tpte;
@@ -2077,15 +2076,13 @@ pmap_collect(pmap_t locked_pmap, struct 
 			pmap_invalidate_page(pmap, va);
 			pmap_free_zero_pages(free);
 			TAILQ_REMOVE(&m->md.pv_list, pv, pv_list);
-			if (TAILQ_EMPTY(&m->md.pv_list)) {
-				pvh = pa_to_pvh(VM_PAGE_TO_PHYS(m));
-				if (TAILQ_EMPTY(&pvh->pv_list))
-					vm_page_flag_clear(m, PG_WRITEABLE);
-			}
 			free_pv_entry(pmap, pv);
 			if (pmap != locked_pmap)
 				PMAP_UNLOCK(pmap);
 		}
+		if (TAILQ_EMPTY(&m->md.pv_list) &&
+		    TAILQ_EMPTY(&pa_to_pvh(VM_PAGE_TO_PHYS(m))->pv_list))
+			vm_page_flag_clear(m, PG_WRITEABLE);
 	}
 }
 

Modified: head/sys/i386/i386/pmap.c
==============================================================================
--- head/sys/i386/i386/pmap.c	Sun May 30 14:20:32 2010	(r208656)
+++ head/sys/i386/i386/pmap.c	Sun May 30 18:48:41 2010	(r208657)
@@ -2147,7 +2147,6 @@ SYSCTL_INT(_vm_pmap, OID_AUTO, pmap_coll
 static void
 pmap_collect(pmap_t locked_pmap, struct vpgqueues *vpq)
 {
-	struct md_page *pvh;
 	pd_entry_t *pde;
 	pmap_t pmap;
 	pt_entry_t *pte, tpte;
@@ -2184,15 +2183,13 @@ pmap_collect(pmap_t locked_pmap, struct 
 			pmap_invalidate_page(pmap, va);
 			pmap_free_zero_pages(free);
 			TAILQ_REMOVE(&m->md.pv_list, pv, pv_list);
-			if (TAILQ_EMPTY(&m->md.pv_list)) {
-				pvh = pa_to_pvh(VM_PAGE_TO_PHYS(m));
-				if (TAILQ_EMPTY(&pvh->pv_list))
-					vm_page_flag_clear(m, PG_WRITEABLE);
-			}
 			free_pv_entry(pmap, pv);
 			if (pmap != locked_pmap)
 				PMAP_UNLOCK(pmap);
 		}
+		if (TAILQ_EMPTY(&m->md.pv_list) &&
+		    TAILQ_EMPTY(&pa_to_pvh(VM_PAGE_TO_PHYS(m))->pv_list))
+			vm_page_flag_clear(m, PG_WRITEABLE);
 	}
 	sched_unpin();
 }

Modified: head/sys/i386/xen/pmap.c
==============================================================================
--- head/sys/i386/xen/pmap.c	Sun May 30 14:20:32 2010	(r208656)
+++ head/sys/i386/xen/pmap.c	Sun May 30 18:48:41 2010	(r208657)
@@ -2078,12 +2078,12 @@ pmap_collect(pmap_t locked_pmap, struct 
 			pmap_invalidate_page(pmap, va);
 			pmap_free_zero_pages(free);
 			TAILQ_REMOVE(&m->md.pv_list, pv, pv_list);
-			if (TAILQ_EMPTY(&m->md.pv_list))
-				vm_page_flag_clear(m, PG_WRITEABLE);
 			free_pv_entry(pmap, pv);
 			if (pmap != locked_pmap)
 				PMAP_UNLOCK(pmap);
 		}
+		if (TAILQ_EMPTY(&m->md.pv_list))
+			vm_page_flag_clear(m, PG_WRITEABLE);
 	}
 	sched_unpin();
 }