Phase 0 devices just running @100MHz?

pHilipp Zabel philipp.zabel at gmail.com
Fri Mar 9 10:07:00 CET 2007


On 3/8/07, Nils Faerber <nils.faerber at kernelconcepts.de> wrote:
> Pierre Hébert schrieb:
> > It doesn't seem so bad : my s3c2440 at 400MHz shows 199bogomips, so at
> > 200MHz 100bogomips seems correct (s3c2440 has the same cpu as s3c2410).
> > I don't know if the bogomips indication is a value in which we can really
> > trust, these little devices are really efficient even at
> > 100/200bogomips.
>
> The bogomips result is a little different depending on the core
> architecture. So for the Samsung CPU bogomips ~= 1/2 MHz.
> OK, good to know!
> A PXA270 I have on my desk has the ~ 1:1 bogomips to MHz mapping...

I guess this depends on how many cycles the __delay(loops_per_jiffy) loop

ENTRY(__delay)
	subs	r0, r0, 1
	bhi	__delay
	mov	pc,lr

takes on the given cpu.
On the S3C2440 subs takes 1S and bhi takes 2S+1N cycles.
Is information about the PXA27x instruction cycle times available somewhere?

regards
Philipp




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