Subject: What causes a process to wait on uvn_fp2?
To: None <>
From: Dave Huang <>
List: current-users
Date: 04/04/2004 01:09:17
I have a set of Video CDs that I want to extract the MPEGs off of; I'm
using "vcdxrip" from the sysutils/vcdimager-devel package, along with
"cdrdao read-cd" from sysutils/cdrdao to do the job (vcdxrip doesn't
know how to read from the CD directly under NetBSD, so I use cdrdao to
make an image file, then let vcdxrip read from the image file).

If I have vcdxrip reading from one image file while cdrdao is reading
another CD, vcdxrip spends a lot of time waiting on "uvn_fp2":

500 8687 7020   9 -18  0 600 1896 uvn_fp2 D+   p0 0:03.25 vcdxrip -o gulkeeva9.

and the cdrdao process will often pause for 20-30 seconds. Sometimes
simply attempting to switch screens will take 10 seconds to take
effect (I'm connected remotely via ssh and use the misc/screen
package). "top" shows other processes in uvn_fp2 also.

If I run vcdxrip by itself, on an otherwise idle system, the system
doesn't slow down quite as badly, but it does still get slow. tcsh's
built-in "time" reports this for vcdxrip running on a 470MB file:
15.324u 22.063s 4:45.33 13.1%   0+0k 5+78io 13pf+0w

It doesn't seem like reading 470MB of data from a file and writing it
back out to a set of files should take almost 5 minutes, nor should it
slow down other processes so drastically. Simply catting the file to
/dev/null takes 26 seconds. So, I'm wondering just what is "uvn_fp2"
and why would a process be waiting on it? Is there something I can
look at to see where all the time is going?

I'm running NetBSD/alpha, noticed the problem with a 1.6ZH kernel from
Jan 24, and am now running 2.0_BETA from Apr 3. System is a AlphaPC
164 500MHz, 256MB RAM. I do not have NEW_BUFQ_STRATEGY enabled (there
seem to be mixed feelings about it; perhaps I should give it a try and
see what it does for me).
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