vfs.lookup_shared

[Pawel Jakub Dawidek]

On Sat, May 24, 2008 at 08:52:24AM +0000, Kris Kennaway wrote:
> 
> On Fri, May 23, 2008 at 05:16:16PM -1000, Jeff Roberson wrote:
> > On Fri, 23 May 2008, Xin LI wrote:
> > 
> > >-----BEGIN PGP SIGNED MESSAGE-----
> > >Hash: SHA1
> > >
> > >Hi,
> > >
> > >Is there any reason behind we don't have vfs.lookup_shared enabled by
> > >default?
> > 
> > We have discussed enabling it by default once the ffs shared lookup 
> > support is complete.  Unfortunately ffs is still not 100% reliable.  I 
> > want to verify that it's an ffs problem and not a problem with the vfs 
> > generic code which would effect all filesystems before we enable it by 
> > default.
> 
> Also, until Attilio's recent lockmgr work, shared lockmgr locks were
> starving exclusive lockmgr lock requests, leading to performance
> problems on some workloads with the only filesystem that supported
> shared locking (NFS).  This is now fixed though.

ZFS also supports shared locking and shared lookups. I've
vfs.lookup_shared=1 on my ZFS-only laptop for more than a year now and
never had a problem. Although it is only a laptop...

-- 
Pawel Jakub Dawidek                       http://www.wheel.pl
pjd at FreeBSD.org                           http://www.FreeBSD.org
FreeBSD committer                         Am I Evil? Yes, I Am!
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