Subject: NFS3 + kerberos: performance issues
From: Vladimir Elisseev <vovan@vovan.nl>
To: linux-nfs@vger.kernel.org
Content-Type: text/plain; charset="UTF-8"
Date: Fri, 03 Jun 2011 09:29:19 +0200
Message-ID: <1307086159.1052.19.camel@vovan.net.home>
Sender: linux-nfs-owner@vger.kernel.org
MIME-Version: 1.0

Hello,

After using nfs3 with kerberos for a while I discovered very poor
performance for some file operations like creation of files. There are
two observations:
- the overal nfs3 performance is good: for instance copying large files
works fine
- this poor performance is definitely related to kerberos as the same
volume exported without sec=krb5 works ~10 times faster with creating
files
I'd appreciate if somebody can explain this behaviour?

Below are some details about NFS server and client:
server:
- kernel 2.6.36
- export options rw,sec=krb5,no_root_squash,no_subtree_check
- nfs-utils 1.2.3

client:
- kernel 2.6.38 or 2.6.39 
- mout options (from /proc/mounts):
rw,nosuid,nodev,noatime,vers=3,rsize=524288,wsize=524288,namlen=255,hard,proto=tcp,timeo=600,retrans=2,sec=krb5,mountaddr=192.168.1.219,mountvers=3,mountport=32767,mountproto=tcp,local_lock=none,addr=192.168.1.219

when the same volume exported without sec=krb5, the only option changes
in /proc/mounts is sec=sys

Regards,
Vlad.