>On Mon, May 21, 2007 at 06:21:40PM -0500, Albert Chin wrote: >> On Mon, May 21, 2007 at 06:11:36PM -0500, Nicolas Williams wrote: >> > On Mon, May 21, 2007 at 06:09:46PM -0500, Albert Chin wrote: >> > > But still, how is tar/SSH any more multi-threaded than tar/NFS? >> > >> > It's not that it is, but that NFS sync semantics and ZFS sync >> > semantics conspire against single-threaded performance. >> >> What's why we have "set zfs:zfs_nocacheflush = 1" in /etc/system. But, >> that's only helps ZFS. Is there something similar for NFS? > >NFS's semantics for open() and friends is that they are synchronous, >whereas POSIX's semantics are that they are not. You're paying for a >sync() after every open.
I'm not sure the semantics of NFS are at all relevant for the complete performance picture. NFS writes are(/used to be) synchronous, but the client hides that from processes; similarly, the client could hide the fact that creates are synchronous, but that's a bit trickier because creates can fail. Casper _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
