Date: Sat, 17 Apr 2010 18:35:07 +0000 (UTC) From: Alan Cox <alc@FreeBSD.org> To: cvs-src-old@freebsd.org Subject: cvs commit: src/sys/vm vm_object.c Message-ID: <201004171835.o3HIZTxT068705@repoman.freebsd.org>
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alc 2010-04-17 18:35:07 UTC
FreeBSD src repository
Modified files:
sys/vm vm_object.c
Log:
SVN rev 206768 on 2010-04-17 18:35:07Z by alc
In vm_object_backing_scan(), setting PG_REFERENCED on a page before
sleeping on that page is nonsensical. Doing so reduces the likelihood
that the page daemon will reclaim the page before the thread waiting in
vm_object_backing_scan() is reawakened. However, it does not guarantee
that the page is not reclaimed, so vm_object_backing_scan() restarts
after reawakening. More importantly, this muddles the meaning of
PG_REFERENCED. There is no reason to believe that the caller of
vm_object_backing_scan() is going to use (i.e., access) the contents of
the page. There is especially no reason to believe that an access is
more likely because vm_object_backing_scan() had to sleep on the page.
Discussed with: kib
MFC after: 3 weeks
Revision Changes Path
1.410 +0 -3 src/sys/vm/vm_object.c
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