AMD Athlon64 cool'n quiet - questions

[Alexander Volovics]

On Mon, Mar 21, 2005 at 01:19:43PM +0000, James Wilkinson wrote:
> Alexander Volovics wrote:
 
> > However I have only ever seen 2 freqencies in use: 1000 and 2200.
> > This could because 1800/2000 are excluded from use somewhere or
> > because they are 'transient states', only used when switching from
> > 1000 to 2200.
 
> How to see intermediate speeds in use (my CPU is a 3200+, so 2000 is its
> normal state, and it only has 1800 as an intermediate speed):
> 
>  * Open two xterms on a basically idle system.
> 
>  * Become root in one of them (you need to be root to read the current
>    speed through sysfs).
> 
>  * Run
> [root at kendrick ~]# cd /sys/devices/system/cpu/cpu0/cpufreq
> [root at kendrick cpufreq]# while true ; do cat cpuinfo_cur_freq ; sleep 1 ; done
> 
>    It will keep printing the speed in kHz.
> 
>  * In the other xterm, run
> dd if=/dev/zero of=/dev/null
>    (which is a nice do-nothing CPU eater). Watch the speed in the root
>    x-term go to max.
> 
>  * Kill the dd job with control-C.
> 
>  * Watch (in my case, 1800000) an intermediate speed appear for a couple
>    of seconds in the root xterm.
> 
>  * Kill the while loop with control-C.

Yes, this does demonstrate it nicely. In my case I saw both intermediate
speeds reported a few times before it settled down to a stable 1000 again.

But this indeed seems to indicate that these are only 'stepping stones'
between 1000 and 2200. Can they be exploited in some useful way, and how?
(that is except for setting a max/min cpuspeed smaller/larger
 than the actual max/min, which I suppose you can do).
 
> I don't know about you, but most of my computer usage tends to be things
> like surfing the web, writing e-mails, or listening to music. That's
> stuff you can do perfectly well on a 500 MHz computer. You don't need
> more than 1 GHz of Athlon 64 power, so the system keeps clock speed down
> to 1 GHz.

In my case mostly too. But I still have some activities where I can
exploit the full power.

Thanks for the 'demonstration'.

Alexander