Author: jeff
Date: Sat Mar 28 02:36:49 2015
New Revision: 280774
URL: https://svnweb.freebsd.org/changeset/base/280774
Log:
- Eliminate pagequeue locking in the dirty code in vm_pageout_scan().
- Use a more precise series of tests to see if the page changed while we
were locking the vnode.
Reviewed by: alc
Sponsored by: EMC / Isilon
Modified:
head/sys/vm/vm_pageout.c
Modified: head/sys/vm/vm_pageout.c
==============================================================================
--- head/sys/vm/vm_pageout.c Sat Mar 28 01:11:18 2015 (r280773)
+++ head/sys/vm/vm_pageout.c Sat Mar 28 02:36:49 2015 (r280774)
@@ -1157,6 +1157,7 @@ vm_pageout_scan(struct vm_domain *vmd, i
int swap_pageouts_ok;
struct vnode *vp = NULL;
struct mount *mp = NULL;
+ vm_pindex_t pindex;
if ((object->type != OBJT_SWAP) && (object->type !=
OBJT_DEFAULT)) {
swap_pageouts_ok = 1;
@@ -1217,6 +1218,7 @@ vm_pageout_scan(struct vm_domain *vmd, i
KASSERT(mp != NULL,
("vp %p with NULL v_mount", vp));
vm_object_reference_locked(object);
+ pindex = m->pindex;
VM_OBJECT_WUNLOCK(object);
lockmode = MNT_SHARED_WRITES(vp->v_mount) ?
LK_SHARED : LK_EXCLUSIVE;
@@ -1231,17 +1233,18 @@ vm_pageout_scan(struct vm_domain *vmd, i
}
VM_OBJECT_WLOCK(object);
vm_page_lock(m);
- vm_pagequeue_lock(pq);
- queues_locked = TRUE;
/*
- * The page might have been moved to another
- * queue during potential blocking in vget()
- * above. The page might have been freed and
- * reused for another vnode.
+ * While the object and page were unlocked,
+ * the page may have been
+ * (1) moved to a different queue,
+ * (2) reallocated to a different object,
+ * (3) reallocated to a different offset, or
+ * (4) cleaned.
*/
if (m->queue != PQ_INACTIVE ||
m->object != object ||
- TAILQ_NEXT(m, plinks.q) !=
&vmd->vmd_marker) {
+ m->pindex != pindex ||
+ m->dirty == 0) {
vm_page_unlock(m);
if (object->flags & OBJ_MIGHTBEDIRTY)
vnodes_skipped++;
@@ -1271,8 +1274,6 @@ vm_pageout_scan(struct vm_domain *vmd, i
vnodes_skipped++;
goto unlock_and_continue;
}
- vm_pagequeue_unlock(pq);
- queues_locked = FALSE;
}
/*
@@ -1293,10 +1294,6 @@ unlock_and_continue:
vm_page_lock_assert(m, MA_NOTOWNED);
VM_OBJECT_WUNLOCK(object);
if (mp != NULL) {
- if (queues_locked) {
- vm_pagequeue_unlock(pq);
- queues_locked = FALSE;
- }
if (vp != NULL)
vput(vp);
vm_object_deallocate(object);
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