Re: 2.2.18Pre Lan Performance Rocks!

Andi Kleen
2000-10-30T06:47:31Z

On Sun, Oct 29, 2000 at 06:35:31PM -0700, Jeff V. Merkey wrote:
> On Mon, Oct 30, 2000 at 12:04:23AM +0000, Alan Cox wrote:
> > > It's still got some problems with NFS (I am seeing a few RPC timeout
> > > errors) so I am backreving to 2.2.17 for the Ute-NWFS release next week,
> > > but it's most impressive.
> >
> > Can you send a summary of the NFS reports to nfs-devel@linux.kernel.org
>
> Yes. I just went home, so I am emailing from my house. I'll post late
> tonight or in the morning. Performance on 100Mbit with NFS going
> Linux->Linux is getting better throughput than IPX NetWare Client ->
> NetWare 5.x on the same network by @ 3%. When you start loading up a
> Linux server, it drops off sharply and NetWare keeps scaling, however,
> this does indicate that the LAN code paths are equivalent relative to
> latency vs. MSM/TSM/HSM in NetWare. NetWare does better caching
> (but we'll fix this in Linux next). I think the ring transitions to
> user space daemons are what are causing the scaling problems
> Linux vs. NetWare.

There are no user space daemons involved in the knfsd fast path, only in slow paths
like mounting.
The main problem I think in knfsd are the numerous copies of the data (e.g. 2+checksumming for
RX with fragments, upto 4 in some specific configurations). They're unfortunately
not trivial to fix. TX is a bit better, it does only one copy usually out of
the page cache. For RX it also helps to have a network card that supports hardware
checksumming.

-Andi