.TL
Machine loading on the teaching machines
.AU
Martin Guy
Chris Downey
20th May 1988
.AB
This document follows on from an earlier document,
.ft I
The case for Clipper CPU upgrades for
the undergraduate teaching machines  
(May 1988)
.ft P
and provides data on current machine loading and possible ways forward.
.SH
Current machine loading
.LP
High Level Hardware recommend that a Mk0 Orion configured in the same way
as the teaching machines can support a maximum of sixteen users running
small jobs (limited by memory size), or four users running CPU-intensive jobs.
.LP
We impose a limit of thirty-two simultaneous logins on each machine, and
students still complain that they are forced to work late at night because
they cannot gain access to the machine during the day;
there are too many others wanting to use it.
Once the number of users goes over 24
.LP
Note that we get much better performance out of an Orion than most sites,
because much of the CPU load due to terminal handling (in particular,
the per-character interrupts) is taken up by the networked PADs and the
Front End Processors (FEPs).
.LP
To a certain extent, the 
users, and by providing a faster turnarnound for each user, enables them to
complete their work in a shorter time.
.SH
A possible solution
.LP
The clipper processor has been measured at eight times faster than a MK0 Orion
(according to the Dhrystone integer benchmark).