From mboxrd@z Thu Jan 1 00:00:00 1970 From: Dag Bakke Subject: Re: cpufreq for older Toshibas with P3-M and ALi chipset? Date: Mon, 03 Jan 2005 00:48:19 +0100 Message-ID: <41D88843.3070606@bakke.com> References: <41D8204F.3090108@bakke.com> <20050102174242.GB15802@dominikbrodowski.de> Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: <20050102174242.GB15802@dominikbrodowski.de> List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: cpufreq-bounces@www.linux.org.uk Errors-To: cpufreq-bounces+glkc-cpufreq=gmane.org@www.linux.org.uk Content-Type: text/plain; charset="us-ascii"; format="flowed" To: cpufreq@www.linux.org.uk Cc: ptb@it.uc3m.es Dominik Brodowski wrote: >Hi, > >On Sun, Jan 02, 2005 at 05:24:47PM +0100, Dag Bakke wrote: > > [snip] >Yes, it is. Mobile Pentium 3 CPU only support two frequency scaling states. >The 8 states you're seeing using cpuswitch are throttling states -- i.e. the >CPU is stopped for short periods of time. However, during these periods the >voltag isn't scaled, so it only leads to a linear reduction of power >compared to a ~ ^3 reduction if voltage is reduced as well. Furthermore, the >state the CPU is in when stopped equals the state the CPU is put into when >there is no work to do -- all this leads to the fact that throttling is >useless in most cases. > > [snip] OK... but this bit.... >>BTW: >>I do notice that if I fiddle with the BIOS settings, I can make the >>laptop boot at "half speed", coming up at 500 MHz instead of 1000. (As >>displayed in /proc/cpuinfo.) And the P-states driver still works, so >>presumably it is possible to combine 'native support' and P-states to >>obtain 16 steps? :-) >> >> > >No :-) Probably this "half speed" mode means the front side bus speed (which >is multiplied inside the CPU) is put to 50%. And unless you find out how >this is accessible during a runtime system, there's no chance to combine >these two. > > ...made me thinking... Will x86info be fooled by throttling states? Will it report the actual clock, or the effective clock taking 'stops' into account? Not to distrust you, but I am trying to figure out if the cpuswitch thingy is throttling or multiple FSB frequencies. Because x86info -mhz reports a likely clock frequency for every cpuswitch step. And if /proc/cpuinfo shows the system running at 500 Mhz and 'step 4' and this is due to a new FSB speed... I am sure you understand my reasoning. Not sure it will mean a lot for power consumption anyway.. Dag B.