nfs server performance (netbsd-5)

[Jukka Marin <jmarin%embedtronics.fi@localhost>]

Hi,

I had to upgrade my file server to netbsd-5 (to be able to run i386PAE
kernels with Xen) and now nfs is acting funny.  First, with only 500 kB/s
load, nfsd is using 10...20% of CPU (2.6 GHz).  Most the of time used is
system time (eg, 19% with 1% interrupt time and 80% idle).  Dom0 is 98-99%
idle.

I never even noticed the load when running NetBSD 4.0 on the same
hardware.

Second, when an NFS client writes to the server (every 1.5 seconds or so),
all other processes pause for a noticeable period of time.  I can see
this while typing this mesasge, for example.

Third, when accessing two different disks on the server, it seems that
accesses to one disk only are being serviced and there is absolutely no
data flowing to or from the other disk.  This is causing serious problems
with real time video and audio recording. :-(

This is how I start nfsd:

nfs_server=YES          nfsd_flags="-t -u -n 16"

I can see only one nfsd process (maybe this is normal; under NetBSD 4.0
I saw 16 processes (or threads)) in top or ps.

The nfs server is a domU with 2048 MB of RAM and the disks are mounted
with softdeps (not brave enough to try out log).

  -jm