Date: Wed, 27 Apr 2005 15:41:44 -0400 From: Brian Fundakowski Feldman <green@freebsd.org> To: Marc Olzheim <marcolz@stack.nl> Cc: freebsd-stable@freebsd.org Subject: Re: NFS client/buffer cache deadlock Message-ID: <20050427194144.GC39270@green.homeunix.org> In-Reply-To: <20050427191938.GE6256@stack.nl> References: <20050426162549.GD5789@green.homeunix.org> <20050426164346.GA68763@stack.nl> <20050426193602.GE5789@green.homeunix.org> <20050427081746.GA66441@stack.nl> <20050427160857.GF5789@green.homeunix.org> <20050427171523.GB5984@stack.nl> <20050427183435.GA39270@green.homeunix.org> <20050427184203.GD6256@stack.nl> <20050427190627.GB39270@green.homeunix.org> <20050427191938.GE6256@stack.nl>
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On Wed, Apr 27, 2005 at 09:19:38PM +0200, Marc Olzheim wrote: > On Wed, Apr 27, 2005 at 03:06:27PM -0400, Brian Fundakowski Feldman wrote: > > > How can I tell whether it uses transactions ? > > > > I am not sure -- it should with NFSv3 though. Does "mount -v" tell > > you anything more detailed? I suppose that nfsstat may also be used > > -- the "commit" count should only increase when it does an NFSv3 > > commit operation. > > > > > The NFS server is mounted with: > > > > > > mount_nfs -c -P -a 0 -r 8192 -w 8192 -i -o rw,noatime,nointr host:/path /nfs/host/path > > > > So the only really visible difference is 6 nfsiod versus 20 nfsiod. I > > think if you increased the nfsiod on that 4.x box to something much > > higher it would deadlock the same, then, assuming that all else is > > equal. > > Well, I took on that challenge and although it seems that the machine > completely hangs itself up for a while, it snaps out of it after it is > done. > > tehethereal tells me it is NFSv3, and the commits increase: > [....] Alright, thanks for testing. So the same bug exists in 4.x but may not actually deadlock the buffer cache in the same circumstances. If you feel like playing with it anymore, I would expect a certain write block size, maximum nfsiod, and total file size being written wouldn't be too hard to find that would deadlock 4.x, too. -- Brian Fundakowski Feldman \'[ FreeBSD ]''''''''''\ <> green@FreeBSD.org \ The Power to Serve! \ Opinions expressed are my own. \,,,,,,,,,,,,,,,,,,,,,,\
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