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In vm_object_madvise() setting PG_REFERENCED on a page before sleeping on

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that page only makes sense if the advice is MADV_WILLNEED.  In that case,
the intention is to activate the page, so discouraging the page daemon
from reclaiming the page makes sense.  In contrast, in the other cases,
MADV_DONTNEED and MADV_FREE, it makes no sense whatsoever to discourage
the page daemon from reclaiming the page by setting PG_REFERENCED.

Wrap a nearby line.

Discussed with:	kib
MFC after:	3 weeks
This commit is contained in:
Alan Cox 2010-04-17 21:14:37 +00:00
parent 1a58736816
commit b11b56b55b
1 changed files with 9 additions and 2 deletions
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11
sys/vm/vm_object.c
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@ -1205,12 +1205,19 @@ shadowlookup:
goto unlock_tobject; goto unlock_tobject;
} }
if ((m->oflags & VPO_BUSY) || m->busy) { if ((m->oflags & VPO_BUSY) || m->busy) {
vm_page_flag_set(m, PG_REFERENCED); if (advise == MADV_WILLNEED)
/*
* Reference the page before unlocking and
* sleeping so that the page daemon is less
* likely to reclaim it.
*/
vm_page_flag_set(m, PG_REFERENCED);
vm_page_unlock_queues(); vm_page_unlock_queues();
if (object != tobject) if (object != tobject)
VM_OBJECT_UNLOCK(object); VM_OBJECT_UNLOCK(object);
m->oflags |= VPO_WANTED; m->oflags |= VPO_WANTED;
msleep(m, VM_OBJECT_MTX(tobject), PDROP | PVM, "madvpo", 0); msleep(m, VM_OBJECT_MTX(tobject), PDROP | PVM, "madvpo",
0);
VM_OBJECT_LOCK(object); VM_OBJECT_LOCK(object);
goto relookup; goto relookup;
} }