On Tue, May 22, 2007 at 10:04:34AM +0200, [EMAIL PROTECTED] wrote: > > >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.
But it sounds tricky enough that it can't be pulled off. It'd be nice to have async versions of all fs-related syscalls... _______________________________________________ zfs-discuss mailing list zfs-discuss@opensolaris.org http://mail.opensolaris.org/mailman/listinfo/zfs-discuss
