Stupid question regarding bogomips and udelay()

[François]

Hello, that's an interesting question!
I'm currently reading the same book, but you've read more than me so far :)

On Mon, Aug 01, 2016 at 08:36:07AM +0300, Aleksander Alekseev wrote:
> * bogomips value (see `cat /proc/cpuinfo`) is determined only once
>   during system boot

As far as I know, I is (was?) the case.

> It's my understanding that it shouldn't work. CPU frequency actually
> changes manually (see cpufrequtils) and/or automatically depending for
> instance on laptop's current battery charge. There is also such a nasty
> thing as Intel Turbo Boost. In other words actual MIPS could be higher
> or lower than measured MIPS. So udealy() can't guarantee anything.

Makes sense. Do you have such machine? Did you try to get bogomips and then
reduce your CPU count / speed and get that number again?

Maybe this value is now dynamic.

Also, did you actually try udealay() in high/low frequency to see wether you
see an actual difference between runs?

Sorry I don't have final answers!

-- 
François