Performance question

mikea mikea at MIKEA.ATH.CX
Wed Oct 8 20:16:19 IST 2003

On Wed, Oct 08, 2003 at 02:02:44PM -0500, Alan Fiebig wrote:
> >Alan,
> >
> >CPU load is not a % but an absolute number indicating the number of
> >ready to run processes in the system.  A load of 10 indicates that 10
> >processes are fighting for the CPU...

> If this is the case, then why does TOP have a percent sign next to the
> stat? If TOP shows:
>   91.4% idle

> does this not mean that my CPU load is not (100% - 76.4%)= 8.6%?

One of you is looking at apples; the other is looking at oranges.
They're different askects of what's going on inside the box.

The CPU load may be only 8.6%, but that doesn't mean that there's
a way to exploit the rest of it, if the CPU is waiting on I/O. I
fully expect that this the case, from previous discussion on this
and from 30+ years doing system tuning on large mainframe computers
where being I/O bound is common, though less so now.

The fact that you have ten tasks competing for the CPU and a %idle
that low means that there is a *SERIOUS* bottleneck somewhere. It
may be RAM, but it's most probably I/O.

Mike Andrews
mikea at
Tired old sysadmin

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