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Handle held pages earlier in the inactive queue scan.

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Reviewed by:	kib
Sponsored by:	EMC / Isilon Storage Division
This commit is contained in:
alc 2015-09-01 06:21:12 +00:00
parent bfe32e53e7
commit 663f8328dc
1 changed files with 33 additions and 31 deletions
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64
sys/vm/vm_pageout.c
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@ -1125,31 +1125,45 @@ vm_pageout_scan(struct vm_domain *vmd, int pass)
* different position within the queue. In either
* case, addl_page_shortage should not be incremented.
*/
if (!vm_pageout_page_lock(m, &next)) {
vm_page_unlock(m);
continue;
if (!vm_pageout_page_lock(m, &next))
goto unlock_page;
else if (m->hold_count != 0) {
/*
* Held pages are essentially stuck in the
* queue. So, they ought to be discounted
* from the inactive count. See the
* calculation of the page_shortage for the
* loop over the active queue below.
*/
addl_page_shortage++;
goto unlock_page;
}
object = m->object;
if (!VM_OBJECT_TRYWLOCK(object) &&
!vm_pageout_fallback_object_lock(m, &next)) {
vm_page_unlock(m);
VM_OBJECT_WUNLOCK(object);
continue;
if (!VM_OBJECT_TRYWLOCK(object)) {
if (!vm_pageout_fallback_object_lock(m, &next))
goto unlock_object;
else if (m->hold_count != 0) {
addl_page_shortage++;
goto unlock_object;
}
}
/*
* Don't mess with busy pages, keep them at at the
* front of the queue, most likely they are being
* paged out. Increment addl_page_shortage for busy
* pages, because they may leave the inactive queue
* shortly after page scan is finished.
*/
if (vm_page_busied(m)) {
vm_page_unlock(m);
VM_OBJECT_WUNLOCK(object);
/*
* Don't mess with busy pages. Leave them at
* the front of the queue. Most likely, they
* are being paged out and will leave the
* queue shortly after the scan finishes. So,
* they ought to be discounted from the
* inactive count.
*/
addl_page_shortage++;
unlock_object:
VM_OBJECT_WUNLOCK(object);
unlock_page:
vm_page_unlock(m);
continue;
}
KASSERT(m->hold_count == 0, ("Held page %p", m));
/*
* We unlock the inactive page queue, invalidating the
@ -1164,7 +1178,7 @@ vm_pageout_scan(struct vm_domain *vmd, int pass)
* Invalid pages can be easily freed. They cannot be
* mapped, vm_page_free() asserts this.
*/
if (m->valid == 0 && m->hold_count == 0) {
if (m->valid == 0) {
vm_page_free(m);
PCPU_INC(cnt.v_dfree);
--page_shortage;
@ -1208,18 +1222,6 @@ vm_pageout_scan(struct vm_domain *vmd, int pass)
goto drop_page;
}
if (m->hold_count != 0) {
/*
* Held pages are essentially stuck in the
* queue. So, they ought to be discounted
* from the inactive count. See the
* calculation of the page_shortage for the
* loop over the active queue below.
*/
addl_page_shortage++;
goto drop_page;
}
/*
* If the page appears to be clean at the machine-independent
* layer, then remove all of its mappings from the pmap in