Why is NFSv4 so slow?

[Rick Macklem]

----- Original Message -----
> On Wed, Sep 01, 2010 at 11:46:30AM -0400, Rick Macklem wrote:
> > >
> > > I am experiencing similar issues with newnfs:
> > >
> > > 1) I have two clients that each get around 0.5MiB/s to 2.6MiB/s
> > > reading
> > > from the NFS4-share on Gbit-Lan
> > >
> > > 2) Mounting with -t newnfs -o nfsv3 results in no performance gain
> > > whatsoever.
> > >
> > > 3) Mounting with -t nfs results in 58MiB/s ! (Netcat has similar
> > > performance) ??? not a hardware/driver issue from my pov
> >
> > Ok, so it does sound like an issue in the experimental client and
> > not NFSv4. For the most part, the read code is the same as
> > the regular client, but it hasn't been brought up-to-date
> > with recent changes.
> 
> Do you (or will you soon) have some patches I/we could test? I'm
> willing to try anything to avoid mounting ten or so subdirectories in
> each of my mount points.
> 
One other thing you could do is run this in a loop while you have a
slow read running. The client threads must be blocked somewhere a
lot if the read rate is so slow. (Then take a look at "xxx" and please
email it to me too.)

ps axHl >> xxx
sleep 1

rick