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SubjectRe: BogoMIPS and changed CPU speed
On Thu, Jul 20, 2000 at 12:08:48PM +0000, Erik Mouw wrote:
> On Wed, 19 Jul 2000 16:39:06 +0200, David Balazic wrote:
> > As I understand the BogoMIPS value is used for some fine grained
> > delays. How does then the system survive a big change in the processor
> > speed when :
> > - user changes FSB on the fly ( possible with newer mainboards,
> > I never tried it though )
> > - CPU goes to lower clock due to power management
> > - user (de)activates TURBO on older x86 computers
>
> The system survives the speed change very well. I've done clock scaling on
> StrongARM SA1100 CPUs (see signature), and I could change the clock speed
> from 59 to 265 MHz without problems. The proper implementation should

Depends on the drivers you're using - one of the SCSI drivers failed to
work properly on certain alphas were udelay()'s speed varied by a factor
of 2 depending on the next instruction after the udelay assembly (this
has been fixed now).

Fixing loops_per_sec to the highest possible value should always work
though.

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