On Thu, 2006-02-02 at 14:13, David S. Miller wrote: > From: Greg Banks <[EMAIL PROTECTED]> > Date: Thu, 02 Feb 2006 14:06:06 +1100 > > > On Thu, 2006-02-02 at 13:46, David S. Miller wrote: > > > I know SAMBA is using sendfile() (when the client has the oplock held, > > > which basically is "always"), is NFS doing so as well? > > > > NFS is an in-kernel server, and uses sock->ops->sendpage directly. > > Great. > > Then where's all the TX overhead for NFS? All the small transactions > and the sunrpc header munging?
Multiple trips down through TCP, qdisc, and the driver for each NFS packet sent: one for the header and one for each page. Lots of locks need to be taken and dropped, all this while multiple nfds on multiple CPUs are all trying to reply to NFS RPCs at the same time. And in the particular case of the SN2 architecture, time spent flushing PCI writes in the driver (less of an issue now that host send rings are the default in tg3). Greg. -- Greg Banks, R&D Software Engineer, SGI Australian Software Group. I don't speak for SGI. - To unsubscribe from this list: send the line "unsubscribe netdev" in the body of a message to [EMAIL PROTECTED] More majordomo info at http://vger.kernel.org/majordomo-info.html
