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SubjectRe: CPU load
On Mon, 12 Feb 2007 16:44:22 +1100 "Con Kolivas" <kernel@kolivas.org> wrote:
>
> The kernel looks at what is using cpu _only_ during the timer
> interrupt. Which means if your HZ is 1000 it looks at what is running
> at precisely the moment those 1000 timer ticks occur. It is
> theoretically possible using this measurement system to use >99% cpu
> and record 0 usage if you time your cpu usage properly. It gets even
> more inaccurate at lower HZ values for the same reason.

That is not true on all architecures, some do more accurate accounting by
recording the times at user/kernel/interrupt transitions ...

--
Cheers,
Stephen Rothwell sfr@canb.auug.org.au
http://www.canb.auug.org.au/~sfr/
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