🚀 go-pugleaf

Hi Jeff!

In article <15248@sequent.UUCP> jjb@sequent.UUCP (Jeff Berkowitz) writes:
>How does a four processor 9845 handle load average?

The total number of processes in run state or in non-interruptable sleep.

>In addition, some daemons refuse to run if the "load average" is very high.

Anything besides sendmail?

>Since customers can also write code that checks this, the computed load ave-
>rage should reflect reality; each processor can simultaneously run a program.

Any program that decides to alter its behavior based on load average *better*
make that value run-time selectable. Sendmail does.

I understand that you are trying to make this relatively meaningless number
more useful and intuitive. But given per-process multiprocessing, I don't see
how "more processors" differs from "faster processors." Taken to its logical
extreme, it would seem that every vendor should divide their load average by
their VUPS rating. :-) 

It's up to the system administration to determine what an "acceptable" load
average is. This is going to vary based on the needs of the site, and the type
of machine they are using. If I add more horsepower to my machine, then in my
mind I've increaed the allowable load average, regardless of whether I did it
by adding bigger processors (9805 to 9815, or Balance to Symmetry) or by
adding more processors. If the load average is divided by the number of CPUs,
then the calculation is distorted; I end up mentally multiplying the number I
see by a magic factor to turn it back into something I can use. 

On the other hand, there *is* the warm fuzzy of installing more processors
and seeing the load average drop. Me, I'm not real wild about warm fuzzies.
(A warm tribble, perhaps....)

>Does this mean performance does not scale linearly?

How is this relevant to the discussion?

To answer the question, though -- How linear is linear? :-) The Pyramid 9000
is within 5% of linear. I gather that it's not quite as flat as a Balance,
Symmetry, Multimax, or Elxsi; but it seems to be considerably more linear
than a VAX 8800.

<csg>