swap space exhaustion

[Geoff Collyer]

Jim Barton:
>>filling up swap won't crash the machine, the OS will instead start gunning
>>down processes...

Henry Spencer:
>Would it be too much to ask that this be made a configuration option?
>Some of us think that it is much better for a machine to crash cleanly
>than to try to keep running with crucial processes (Murphy's Law says that
>the gunned-down processes will be important daemons) dying randomly and
>disrupting operations in bizarre ways.

I would like to amplify Henry's comment.  Why strafe innocent
processes?  When possible, I think returning ENOMEM from fork, exec,
sbrk and the like is preferable; when that is not possible, given that
sensible modern Unixes can be made to autoboot after a panic (ahem!), a
panic("out of swap space") will cause a brief interruption and a clean
start.  Strafing processes (on our SunOS 3.x systems) has usually
resulted in the deaths of inetd and sometimes ypbind or ypserv.  After
killing such critical daemons, the system was dead in the water and had
to be manually crashed (L1-A key) and booted.  This is not what you
want from a timesharing system (pardon my heresy) that is meant to run
unattended much of the time.
-- 
Geoff Collyer		utzoo!utstat!geoff, geoff at utstat.toronto.edu