On Tue, Jul 20, 2010 at 07:30:44PM +0300, Trk Edwin wrote:
> On Tue, 20 Jul 2010 18:25:39 +0200
> Paul Zimmermann <paul.zimmerm...@loria.fr> wrote:
>
> > > I'm pleased to announce that AMD (1) donated two 12-cores
> > > Magny-Cours processors running at 1.5 GHz...
> >
> > /proc/cpuinfo says only 800Mhz, as says GMP's speed:
> >
> > zimme...@gcc10:~/gmp-5.0.1/tune$ ./speed -s 1000000 mpn_mul
> > overhead 0.000000008 secs, precision 10000 units of 1.25e-09 secs,
> > CPU freq 800.00 MHz mpn_mul
> > 1000000 1.432090000
> >
> > Also the web page says "2x12x1.9 GHz". Which one is correct?
>
> I think frequency scaling is on, if you do a 'cat /proc/cpuinfo|grep
> MHz' you'll see some cores at 1500, some at 800.
> make -j12 is definitely fast on this box, I don't think its 800 Mhz all
> the time.
1500MHz isn't a shipping clock speed for Magny-Cours, is it? Anyway,
TSC counting says 1500 MHz:
#include <stdio.h>
#include <stdlib.h>
unsigned long long tsc(void) {
unsigned long high, low;
unsigned long long tsc;
__asm("rdtsc": "=a" (low), "=d" (high));
tsc = high << 32;
tsc += low;
return tsc;
}
int main(void) {
unsigned long long now, then, delta;
then = tsc();
sleep(1);
now = tsc();
delta = now - then;
printf("%llu\n", delta);
return EXIT_SUCCESS;
}
jspe...@gcc10:~$ ./test
1500348673
jspe...@gcc10:~$ ./test
1500356681
jspe...@gcc10:~$ ./test
1500355956
cpufreq also says 1.5GHz:
analyzing CPU 0:
driver: powernow-k8
CPUs which need to switch frequency at the same time: 0
hardware limits: 800 MHz - 1.50 GHz
available frequency steps: 1.50 GHz, 1.20 GHz, 1000 MHz, 900 MHz,
800 MHz
available cpufreq governors: powersave, userspace, conservative,
ondemand, performance
current policy: frequency should be within 800 MHz and 1.50 GHz.
The governor "ondemand" may decide which speed to
use
within this range.
current CPU frequency is 800 MHz.
cpufreq stats: 1.50 GHz:3.45%, 1.20 GHz:0.49%, 1000 MHz:0.00%, 900
MHz:0.02%, 800 MHz:96.03% (1600363)
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