Phase 0 devices just running @100MHz?

Siarhei Siamashka siarhei.siamashka at
Fri Mar 9 10:33:31 CET 2007

On Friday 09 March 2007 11:07, pHilipp Zabel wrote:
> On 3/8/07, Nils Faerber <nils.faerber at> 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?

If you are interested in estimating cpu clock frequency, you can try a simple
test program I have written some time ago:

A few references related to arm cpu performance.

Instruction timings and optimization guide for ARM9E:
Instruction timings and optimization guide for ARM11 (used in OMAP2):
Instruction timings and optimization guide for Intel XScale:
Instruction timings and optimization guide for Cortex (used in OMAP3):

Comparison of ARM7 and ARM9:
Comparison of ARM9 and Cortex:

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