nfs client speed lower than expected.

[Vincent Hoffman]

Hi all,
        What kind of speed should I be expecting over an NFS mount from
a linux box using a gig interface (igb)? I'm seeing linux clients
getting approx 2 or 3 times the throughput rsyncing files from a linux
nfs server that i get from a 8-stable FreeBSD client.
representative results
7.26MB/s - Freebsd client
21.10MB/s liunx client
I've tried a variety of files to try and take caching out of the
equation, I've tweaked a few sysctls after much googling

kern.ipc.maxsockbuf=4000000
net.inet.tcp.sendbuf_max=16777216
net.inet.tcp.recvbuf_max=16777216
net.inet.tcp.sendbuf_inc=16384
net.inet.tcp.recvbuf_inc=524288
net.inet.udp.recvspace=65535
net.local.stream.recvspace=65535
net.local.stream.sendspace=65535

with no obvious improvement.
freebsd mount options
ro,noatime,noexec,nosuid,udp,nfsv3,rsize=1024,wsize=1024,bg,hard,intr,timeout=4,retrans=4
linux mount options
_netdev,ro,noatime,nodev,noexec,nosuid,proto=udp,vers=3,rsize=1k,wsize=1k,bg,hard,intr,timeo=4,retrans=4

I have seen that using the linux server as an nfs client to write to the
NFS server on the freebsd box gives similar performance to a linux
client pulling from the linux server so I'm guessing its something to do
with the freebsd nfs client?

Any suggestions/clues welcome.

Thanks,
Vince