NFS on 10G interface terribly slow

Scott Larson stl at
Thu Jun 25 23:56:13 UTC 2015

     We've got 10.0 and 10.1 servers accessing Isilon and Nexenta via NFS
with Intel 10G gear and bursting to near wire speed with the stock
MTU/rsize/wsize works as expected. TSO definitely needs to be enabled for
that performance. The fact iperf gives you the expected throughput but NFS
does not would have me looking at tuning for the NFS platform. Other things
to look at: Are all the servers involved negotiating the correct speed and
duplex, with TSO? Does it need to have the network stack tuned with
whatever it's equivalent of maxsockbuf and send/recvbuf are? Do the switch
ports and NIC counters show any drops or errors? On the FBSD servers you
could also run 'netstat -i -w 1' under load to see if drops are occurring
locally, or 'systat -vmstat' for resource contention problems. But again, a
similar setup here and no such issues have appeared.

*[image: userimage]Scott Larson[image: los angeles]
Systems Administrator[image: wdlogo] <> [image:
linkedin] <> [image: facebook]
<> [image: twitter]
<> [image: instagram]
<>T 310 823 8238 x1106
<310%20823%208238%20x1106>  |  M 310 904 8818 <310%20904%208818>*

On Thu, Jun 25, 2015 at 5:52 AM, Gerrit Kühn <gerrit.kuehn at>

> Hi all,
> We have a recent FreeBSD 10.1 installation here that is supposed to act as
> nfs (v3) client to an Oracle x4-2l server running Soalris 11.2.
> We have Intel 10-Gigabit X540-AT2 NICs on both ends, iperf is showing
> plenty of bandwidth (9.xGB/s) in both directions.
> However, nfs appears to be terribly slow, especially for writing:
> root at crest:~ # dd if=/dev/zero of=/net/hellpool/Z bs=1024k count=1000
> 1000+0 records in
> 1000+0 records out
> 1048576000 bytes transferred in 20.263190 secs (51747824 bytes/sec)
> Reading appears to be faster, but still far away from full bandwidth:
> root at crest:~ # dd of=/dev/null if=/net/hellpool/Z bs=1024k
> 1000+0 records in
> 1000+0 records out
> 1048576000 bytes transferred in 5.129869 secs (204406000 bytes/sec)
> We have already tried to tune rsize/wsize parameters, but they appear to
> have little (if any) impact on these results. Also, neither stripping down
> rxsum, txsum, tso etc. from the interface nor increasing MTU to 9000 for
> jumbo frames did improve anything.
> It is quite embarrassing to achieve way less than 1GBE performance with
> 10GBE equipment. Are there any hints what else might be causing this (and
> how to fix it)?
> cu
>   Gerrit
> _______________________________________________
> freebsd-net at mailing list
> To unsubscribe, send any mail to "freebsd-net-unsubscribe at"

More information about the freebsd-net mailing list