Re: [cobalt-developers] CPU Load average - acceptable

[Paul Gillingwater <paul@xxxxxxxxxxx>]

Quoting Tim Hockin <thockin@xxxxxxx>:
> > He said that you only get into trouble if the value climbs
> > as high as 40.
> > Gerald
> 
> hold on..I didn't say "only".  I said "generally".

Tim is right.  I've seen systems that cope fine with run queues of 40 or so, 
and other systems that were close to total failure with as little as 4.  Again, 
the whole area of UNIX systems performance tuning and analysis is quite 
specialized (or at least it was when I was trained in this area several years 
ago, so I may be a little out of date.)

<rant>
What matters more is how your system performs with the applications over the 
long term and at peak times.  As developers, we need to consider many aspects, 
including usability, reliability and especially security.  It's easy to 
overlook performance, since many people now think that performance bottlenecks 
can be solved by throwing in more memory or a faster CPU.  On the contrary, I 
would like to encourage all developers to develop a sensitivity to performance 
issues.  Ask yourself some basic questions as you develop, like:

1) How well will this scale?
2) Where are the performance bottlenecks?
3) How can I refactor or streamline this code or module?
4) Do I really need all this data from the query, or should I run more queries 
with smaller result sets?
5) Can I add indexes to the tables to make certain queries faster, or optimize 
joins with intermediary tables?

Bottom line is that if you're looking at performance *after* you've developed, 
then you've missed an opportunity to improve the quality of your work.
</rant>

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        Paul Gillingwater
        Managing Director
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E-mail:  paul@xxxxxxxxxxx
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