[Beowulf] scheduler policy design

[Mark Hahn]

> We do advance reservation with backfill, so short jobs will on average
> start sooner than long jobs. We find that this is sufficient
> motivation for the users to at least try to set reasonable walltime
> values.

have you examined the accuracy of your user's estimates,
both underruns and overruns?  the latter will presumably create
some idle cycles, but the latter (if you kill past reservation)
will potentially waste quite large amounts of work.

we've looked at the literature on reservations, and the few studies
that mention user accuracy seem to agree that the problem is dire.