FreeBSD 9.1 NFSv4 client attribute cache not caching ?

[Paul van der Zwan]

I am running a few VirtualBox VMs with 9.1 on my OpenIndiana server and I noticed that make buildworld seem to take much longer 
when the clients mount /usr/src and /usr/obj over NFS V4 than when they use V3.
Unfortunately I have to use V4 as a buildworld on V3 hangs the server completely...
I noticed the number of PUTFH/GETATTR/GETFH calls in in the order of a few thousand per second
and if I snoop the traffic I see the same filenames appear over and over again.
It looks like the client is not caching anything at all and using a server request everytime.
I use the default mount options:
192.168.178.24:/data/ports on /usr/ports (nfs, nfsv4acls)
192.168.178.24:/data/src on /usr/src (nfs, nfsv4acls)
192.168.178.24:/data/obj on /usr/obj (nfs, nfsv4acls)



Any ideas,
 	Paul