Subject: nfsds using all CPU, STATE = "vnlock"
To: None <>
From: Johan A.van Zanten <>
List: netbsd-users
Date: 10/13/2007 17:55:04
 I have a 2.4 Ghz Pentium 4 running NetBSD 3.1-STABLE.

Boot disk is SCSI, but i have two Maxtor 7H500F0 500 GB SATA data-only
drives that i serve out over NFS. They only have one file system each, and
it is "type ffs," but it is mounted with softdeps.

 I recently got a Mac mini (running MacOS 10.4) and an EyeTV 250 plus ( ) to do record
broadcast HD programs for enjoyment on my on schedule.  The data files for
these programs seem to work out to be about 100 MB / minute recorded, or 6
GB for an hour program.  I guess this comes out to be about 1.6 MB/s
sustained I/O.

  On a few occasions, i've seen the CPU use on the pentium4 spike to 100%,
and it's all being consumed (evenly) by the four nfsds, system not user
time.  They are mostly in the "vnlock" state.  When functioning normally
(even when writing the same volume and type of data), they seem to use
less than ~0.30% of the CPU each.

 The system seems to recover, but i have noticed some of the recorded
programs  have lost substantial chunks of data, though that could
also be due to many other factors, such as antenna reception.

  Seems like it's something related to a vnode lock.

 Anyone have any ideas about what's going on when this happens?

 Thanks, johan