is it really better speedstep-ich vs. p4-clockmod cpufreq driver?

From: Riccardo Vestrini
Date: Fri Jul 23 2004 - 13:55:36 EST

it seems that speedstep-ich and acpi cpufreq driver have only two usable
clock frequencies, while p4-clockmod has eight
my cpu is: Intel Mobile Intel(R) Pentium(R) 4 CPU 3.06GHz stepping 09

last 2.6 kernel I tried (2.6.7) has introduced a warning while loading
p4-clockmod module:

p4-clockmod: P4/Xeon(TM) CPU On-Demand Clock Modulation available
p4-clockmod: Warning: Pentium 4-M detected. The speedstep-ich or acpi
cpufreq modules offer voltage scaling in addition of frequency scaling.
You should use either one instead of p4-clockmod, if possible.

so I immediatly switched to speedstep-ich discovering that:
$ cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_available_frequencies
3066590 1599960

while with p4-clockmod I have:
$ cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_available_frequencies
383323 766647 1149971 1533295 1916618 2299942 2683266 3066590

using acpi driver gives a message:
cpufreq: CPU0 - ACPI performance management activated.
cpufreq: P0: 3059 MHz, 24000 mW, 100 uS
cpufreq: *P1: 1596 MHz, 12000 mW, 100 uS
$ cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_available_frequencies
3059000 1596000

i do not know what driver is supposed to be better and why speedstep-ich driver has only two frequencies

thank you


Riccardo Vestrini

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