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Testing whether a page is dirty does not require the page lock. Moreover,

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it may involve a pmap operation that iterates over the page's PV list, so
unnecessarily holding the page lock is undesirable.

MFC after:	1 week
Sponsored by:	EMC / Isilon Storage Division
This commit is contained in:
alc 2015-08-25 01:01:25 +00:00
parent c465848fcf
commit 6181041f9a
1 changed files with 10 additions and 6 deletions
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16
sys/vm/vm_pageout.c
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@ -415,10 +415,13 @@ more:
ib = 0;
break;
}
vm_page_lock(p);
vm_page_test_dirty(p);
if (p->dirty == 0 ||
p->queue != PQ_INACTIVE ||
if (p->dirty == 0) {
ib = 0;
break;
}
vm_page_lock(p);
if (p->queue != PQ_INACTIVE ||
p->hold_count != 0) { /* may be undergoing I/O */
vm_page_unlock(p);
ib = 0;
@ -442,10 +445,11 @@ more:
if ((p = vm_page_next(ps)) == NULL || vm_page_busied(p))
break;
vm_page_lock(p);
vm_page_test_dirty(p);
if (p->dirty == 0 ||
p->queue != PQ_INACTIVE ||
if (p->dirty == 0)
break;
vm_page_lock(p);
if (p->queue != PQ_INACTIVE ||
p->hold_count != 0) { /* may be undergoing I/O */
vm_page_unlock(p);
break;