According to Jukka Marin:
> On Fri, Dec 18, 1998 at 11:49:24AM +1030, Ian Dall wrote:
> > [ ... ]
> > I didn't specify, but my scheme needs to be some mechanism for firing
> > off a process, or waking up an existing process when swap reaches the
> > high water mark.
> 
> Firing up a new process (loading code from disk etc) sounds scary in
> such a situation (where the system tends to lock up completely at the
> moment :-)
> 
Perhaps one can have a newer version of update(8) that also monitors 
for the high-water mark signal.  If no such process can be notified 
(hm, I must confess I'm out of my depth here, but it seems to me that 
the new update(8) would log itself as a handler for an otherwise 
ignored interrupt, alternatively, it can just open a special 
notification pipe), then the system merely refuses to load any non-root 
application whatsoever - I'd like to be able to link to expect's kibitz 
in such a situation, but that may be a bit far-fetched :-)

As for allowing the high-water mark to be altered, this should not be 
possible once the high-water mark has been reached (except to shrink 
it, perhaps) because managing the logistics at this point seems very 
messy.

++L