On Tue, Jan 03, 2012 at 01:45:26AM -0800, Don Lewis wrote: > On 3 Jan, Kostik Belousov wrote: > > > This sounds very plausible. I think that there is no sense in restarting > > the scan if it is requested in async mode at all. See below. > > > > Would be thrilled if this finally solves the svn2cvs issues. > > > > commit 41aaafe5e3be5387949f303b8766da64ee4a521f > > Author: Kostik Belousov <kostik_at_sirion> > > Date: Tue Jan 3 11:16:30 2012 +0200 > > > > Do not restart the scan in vm_object_page_clean() if requested > > mode is async. > > > > Proposed by: truckman > > > > diff --git a/sys/vm/vm_object.c b/sys/vm/vm_object.c > > index 716916f..52fc08b 100644 > > --- a/sys/vm/vm_object.c > > +++ b/sys/vm/vm_object.c > > _at__at_ -841,7 +841,8 _at__at_ rescan: > > if (p->valid == 0) > > continue; > > if (vm_page_sleep_if_busy(p, TRUE, "vpcwai")) { > > - if (object->generation != curgeneration) > > + if ((flags & OBJPC_SYNC) != 0 && > > + object->generation != curgeneration) > > goto rescan; > > np = vm_page_find_least(object, pi); > > continue; > > I wonder if it would make more sense to just skip the busy pages in > async mode instead of sleeping ... > It would be too much weakening the guarantee of the vfs_msync(MNT_NOWAIT) to not write such pages, IMO. Busy state indeed means that the page most likely undergoing the i/o, but in case it is not, we would not write it at all. Lets see whether the change alone helps. Do you agree ?
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