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Code Issues Releases Activity

During traversal of the active queue, try locking the page's containing

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object before accessing the page's flags or the object's reference count.
If the trylock fails, handle the page as though it is busy.
This commit is contained in:
Alan Cox 2004-10-27 18:29:17 +00:00
parent 3904b13fab
commit b08abf6cc0
Notes: svn2git 2020-12-20 02:59:44 +00:00 
svn path=/head/; revision=136996
1 changed files with 12 additions and 4 deletions
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16
sys/vm/vm_pageout.c
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@ -1018,12 +1018,19 @@ vm_pageout_scan(int pass)
("vm_pageout_scan: page %p isn't active", m));
next = TAILQ_NEXT(m, pageq);
object = m->object;
if (!VM_OBJECT_TRYLOCK(object)) {
vm_pageq_requeue(m);
continue;
}
/*
* Don't deactivate pages that are busy.
*/
if ((m->busy != 0) ||
(m->flags & PG_BUSY) ||
(m->hold_count != 0)) {
VM_OBJECT_UNLOCK(object);
vm_pageq_requeue(m);
m = next;
continue;
@ -1039,7 +1046,7 @@ vm_pageout_scan(int pass)
* Check to see "how much" the page has been used.
*/
actcount = 0;
if (m->object->ref_count != 0) {
if (object->ref_count != 0) {
if (m->flags & PG_REFERENCED) {
actcount += 1;
}
@ -1060,15 +1067,15 @@ vm_pageout_scan(int pass)
* Only if an object is currently being used, do we use the
* page activation count stats.
*/
if (actcount && (m->object->ref_count != 0)) {
if (actcount && (object->ref_count != 0)) {
vm_pageq_requeue(m);
} else {
m->act_count -= min(m->act_count, ACT_DECLINE);
if (vm_pageout_algorithm ||
m->object->ref_count == 0 ||
object->ref_count == 0 ||
m->act_count == 0) {
page_shortage--;
if (m->object->ref_count == 0) {
if (object->ref_count == 0) {
pmap_remove_all(m);
if (m->dirty == 0)
vm_page_cache(m);
@ -1081,6 +1088,7 @@ vm_pageout_scan(int pass)
vm_pageq_requeue(m);
}
}
VM_OBJECT_UNLOCK(object);
m = next;
}