Missing swap space?

[Jon J. Brewster]

System: MicroVAX 3600
OS:     Ultrix 3.1
Disk    RA81, RA82

I have allocated roughly 33 Mb of each of the two disks to the "b"
partitions, and declared them as swap in the config file with:

config        vmunix  root on ra0a  swap on ra0b size 66690 \
and ra1b size 66880

(The line in the config file isn't folded.)  However, pstat -s
reports:

pandora[27] %pstat -s
66785k swap configured
        8272k used (1456k text, 0k smem)
        25071k free, 2959k wasted, 33442k missing
        avail: 46*512k 2*256k 3*128k 3*64k 5*32k 5*16k 191*1k

The number of pages missing is suspiciously close to the size
of ra1b, and a previous incarnation of the kernel, with a smaller
ra1b partition exhibited similar behavior -- the missing pages were
almost equal in size to the size of the second swap partition.  TFM
for pstat(8) says that missing pages ususally indicate space allocated
to argdev.  Seems like rather a lot of space.  I wonder if I missed 
something when I configured the system for interleaved swap??