On Tue, Feb 20, 2007 at 03:51:54PM -0500, bfields@xxxxxxxxxxxx wrote: > > On Tue, Feb 20, 2007 at 10:46:51AM -0500, Robert Rappaport wrote: > > We did an experimental distributed lease implementation in gfs(1) a while > > ago. It worked, but was so extremely expensive that there was no point in > > considering it seriously. The problem is that _every_ open and close of > > every file requires a new dlm lock operation. Leases require knowledge > > about the cluster-wide opened/closed state of files, not only that but the > > mode they're open in. > > We're using leases to implement NFSv4 delegations. Delegations are > similar to leases--they come in read and write variants, and they give > clients a guarantee that they'll be warned before another client is > allowed to do a conflicting open--but delegations are completely optional. > A server can deny a delegation for any reason, even when there isn't > necessarily a conflicting open. > > So perhaps we need some way for nfsd to ask the filesystem to give it a > lease, but only if it's easy to do so. Would it be possible to make it > cheap for GFS to give out leases in some particular (hopefully common) > cases? I don't know of any shortcuts off hand, but there could certainly be some. Doing something completely different and not using cluster locks may also be worth investigating. Dave - To unsubscribe from this list: send the line "unsubscribe linux-fsdevel" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
