Determining load on a UNIX machine

[larry hughes]

Can anyone recommend a generic equation that can be used to 
instantaneously determine how busy (i.e. _percent_ busy) a UNIX 
machine is?

I would expect that such an equation would include variables such
as current number of interactive logins, current number of computable
processes (or perhaps using the 1-minute average from the kernel),
and a relative "cpu rating" to indicate the horsepower of the machine.

DEC has published such an equation in the release notes of VMS 5.2
that they use in conjunction with their LAT terminal servers, which
perform dynamic load balancing.  It turns out, however, that the
numbers from that equation, when scaled to form a percentage, do 
somewhat accurately determine how busy a VMS machine is (especially 
when averaged over a short period of time).

Thanks in advance for any information...

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