Hi Folks,

system: ASUS P5aB rev 1.04 BIOS 1011
Proc: K6-III+ ATZ 400 MHz
OS: Debian Lenny 2.6.26

I have set the jumpers for 6x, 100MHz FSB. It runs fine @ 600 MHz, and I could set the speed by steps of 50MHz from 250 to 600 MHz through jumpers on the mainboard. When I enable powernowd the frequency scaling is calculated in the following manner:

available frequency steps: 601 MHz, 534 MHz, 267 MHz, 401 MHz, 468 MHz

This seems to me as steps of ~66 MHz, instead of 50 or even 100 MHz. Is cpufreqd assuming the wrong FSB? Can I specify it somewhere manually?

thx, Mike.

Not on boards that old. You could often set some of it in the BIOS. There are 2 parts
1. Bus speed
2. Multiplier for cpu.

Well, I know I can't specify FSB in the BIOS, but only through the jumpers on the mainboard. However, the K6-III+ is capable of having its multiplier changed on the fly, so I should expect steps of 50 MHz from cpufreqd, since the FSB is 100MHz, and the multiplier steps are of .5. This should mean that cpufreqd calculates the steps of 50 MHz, and not the 66MHz it shows.

Besides this I did a dhrystone test, and its outcome is comparable with approx 450 MHz (~500000 dhrystones/sec), although cat /proc/cpuinfo shows 600 MHz for the CPU. This means cpufreq is getting the wrong FSB for the calculations somehow.

When I boot a linux 2.4 kernel (which don't support cpu throttling) the drystone test is remarkable higher (~680000 dhrystones/sec) and shows true 600MHz.

I know it is old hardware, but since there is cpu throttling support for the K6-III+ in the 2.6 kernel I might expect it should work for my hardware. Is it possible to tell cpufreqd manually what the FSB is?

I believe that cpufreqd now takes 133MHz as FSB which makes it think that a multiplier of 4,5 x 133 = 600MHz, but in the real world it is only 4,5 x 100 = 450MHz.

Maybe its a known issue...

Forget cpufreq, throttling, and all that. They are for a later generation of motherboard chips.

Usually you only have bus speed & multiplier on K6-3 boards. Usually you seem to have Via chipsets also. Been there, suffered that, and have the t-shirt. You may even run into the famous Via 'hardware fault' if the board is poorly set up, and you have a creative sound blaster, although I never did. Again if you have usb, you may run into the 'overcurrent change on hub <n> port <n>' from ehci_hcd and in that case be aware of the option for /etc/modules.d
option ehci_hcd ignore_oc=1

which kills them.

This suggestions are good for follower.

Well, I don't really understand your reply I just want to build a simple fileserver from this hardware and it should be nice to save some power with the scaling thing. On what mainboard (beside certain laptops) should scaling work well with a K6-III+ ?

Ok, build away. No need to compile in cpufreq, as frequency is fixed in that generation of cpu.

The power saving tricks possible with later hardware do not work on that old board.