donna writes:

> > The CPU was used a total of 55.3% of its capacity during this
>  > interval <GI01>
>
>  55% is not a problem

Actually, it probably is a problem.

I've given this lecture a hundred times before, and the only result that I
can see so far is that the ruler I use to whap people's knuckles only gets
larger with each whapping.

The two primary goals of any multiuser, multitasking machine are:

     o to allocate resources to the individual users in the most fair way
possible
     o to keep the CPU 100% busy

A 100% busy CPU is not a sin. It's a virtue.

If you are running multiple jobs at the same time and your CPU is not running
100%, it means that your processes are sitting around waiting on something
mechanical to complete (e.g., disc heads to move, main memory page swaps, etc.).
A 55% CPU utilization means that the CPU is just twiddling its thumbs for 45%
of the time, doing nothing.

If you can determine the source of those mechanical bottlenecks and get your
CPU usage up to 100%, you can improve the speed of your throughput by approx.
2 times, as measured by wall time.

But the same number of CPU seconds (more or less) will still need to be
exhausted by your code, whether the CPU runs at 100% or 10%. If you really want to
improve the performance of your jobs, take a very careful look at your code.
Almost all real performance gains occur because inefficient database accesses
or poorly implemented algorithms are cleaned up.

Wirt Atmar

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