Re: Wrong bogomips after plugging in AC power

Harald Koenig (koenig@tat.physik.uni-tuebingen.de)
Fri, 29 Oct 1999 17:15:10 +0200


On Oct 29, Pavel Machek wrote:

> Hi!
>
> So I've now confirmed that my toshiba can speed-up its cpu under some
> circumstances. When it is powered up while batteries are low (<20%
> will work), it will start with cpu at 150MHz, and bogomips are
> computed accordingly.

at least for the Tecra 750/780 you can cycle though these 3 power modi
(fast/economy/user settings) using Fn-F2.

> If I plug it into AC power, it will speed up to 300MHz, but bogomips
> still have "slow" value. Therefore all udelays are wrong by factor of
> two -- udelay(50) will only wait approx. 25usec. That seems pretty

or 100 usec if you boot in fast mode and later switch to slow mode...

> dangerous to me. Maybe we need some other source of short loops?

would be `nice to have';) but how/when do check/realize that you
have to recalibrate your delay loop ? all real time clock sources
are pretty slow/bad and have slow access, and most likely rdtsc
will be clocked down too:(

Harald

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