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andrewaclt
n00b
Joined: 16 Sep 2006
Posts: 18
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 Posted: Sat Feb 24, 2007 5:59 pm Post subject: [Solved] CPU Frequency Scaling on a P4 |
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Hello,
I've been trying to to save power on my laptop so I figured CPU frequency scaling would help, however it seems my processor, a p4, only supports two steps? This seems kind of odd, could it be a bug or am I really just out of luck? (googling around didn't help...)
cat /proc/cpuinfo :
| Code: | processor : 0
vendor_id : GenuineIntel
cpu family : 15
model : 2
model name : Intel(R) Pentium(R) 4 CPU 2.66GHz
stepping : 9
cpu MHz : 2333.275
cache size : 512 KB
fdiv_bug : no
hlt_bug : no
f00f_bug : no
coma_bug : no
fpu : yes
fpu_exception : yes
cpuid level : 2
wp : yes
flags : fpu vme de pse tsc msr pae mce cx8 sep mtrr pge mca cmov pat pse36 clflush dts acpi mmx fxsr sse sse2 ss ht tm pbe up cid xtpr
bogomips : 5320.87 |
cpufreq-info : | Code: |
cpufrequtils 002: cpufreq-info (C) Dominik Brodowski 2004-2006
Report errors and bugs to linux@brodo.de, please.
analyzing CPU 0:
driver: p4-clockmod
CPUs which need to switch frequency at the same time: 0
hardware limits: 2.33 GHz - 2.67 GHz
available frequency steps: 2.33 GHz, 2.67 GHz
available cpufreq governors: conservative, ondemand, powersave, userspace, performance
current policy: frequency should be within 2.33 GHz and 2.67 GHz.
The governor "conservative" may decide which speed to use
within this range.
current CPU frequency is 2.33 GHz. |
Last edited by andrewaclt on Sun Feb 25, 2007 7:56 pm; edited 1 time in total |
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dev-urandom
Apprentice
Joined: 24 Jun 2005
Posts: 260
Location: Huh?
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| Posted: Sun Feb 25, 2007 1:33 pm Post subject: |
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I am no expert, but afaik no p4 chips support cpu scaling, only the amd cousins have it. Have you checked out the freqd readme?
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erik258
Advocate
Joined: 12 Apr 2005
Posts: 2650
Location: Twin Cities, Minnesota, USA
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| Posted: Sun Feb 25, 2007 6:50 pm Post subject: |
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they have a little cpu scaling. My p4 celeron slows down when running too hot (easy to do in its slimline case, when it's doing folding at home 24/7 ; ) ), but only by about the margin you state. I think the mobile chips probably scale a lot more. Although manufacturers didn't all bother to use mobile chips instead, the P4 line is particularly poorly suited to laptop use.
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LinuxCommando.com is my blog for linux-related scraps and tidbits. Stop by for a visit! |
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andrewaclt
n00b
Joined: 16 Sep 2006
Posts: 18
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| Posted: Sun Feb 25, 2007 7:56 pm Post subject: |
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Thanks,
I guess it's about time for a new laptop :/ |
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MotivatedTea
Apprentice
Joined: 06 Nov 2006
Posts: 269
Location: Toronto, Canada
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| Posted: Sun Feb 25, 2007 10:23 pm Post subject: |
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I also have a laptop with a (slightly slower) P4. I'm using the "acpi-cpufreq" driver (kernel module acpi_cpufreq) instead of "p4-clockmod". I also only get two frequencies, but there's a larger difference between the two percentage-wise:
| Code: | cpufrequtils 002: cpufreq-info (C) Dominik Brodowski 2004-2006
Report errors and bugs to linux@brodo.de, please.
analyzing CPU 0:
driver: acpi-cpufreq
CPUs which need to switch frequency at the same time: 0
hardware limits: 1.20 GHz - 2.00 GHz
available frequency steps: 2.00 GHz, 1.20 GHz
available cpufreq governors: conservative, ondemand, powersave, userspace, performance
current policy: frequency should be within 1.20 GHz and 2.00 GHz.
The governor "ondemand" may decide which speed to use
within this range.
current CPU frequency is 1.20 GHz. |
My /proc/cpuinfo is the same as yours except for the following lines:
| Code: | model name : Mobile Intel(R) Pentium(R) 4 - M CPU 2.00GHz
cpu MHz : 1200.000
bogomips : 2399.06 |
My CPU does have an "M" in the model name, but it's not the Pentium M series of chips. They weren't released when this laptop was made. It's a Pentium 4-M, which, as far as I can tell, is basically a Pentium 4. (It's odd that my CPU has the same family and model number but a different identifying name.) Anyways, since you only have two cpu frequencies, I'd recommend using the "ondemand" governor instead of "conservative". "ondemand" ramps the CPU speed down slowly - but your processor can't do that anyways. "ondemand" responds more quickly, so it should switch to the lower speed sooner when the CPU becomes idle. I use "conservative" on a different laptop where medium-intensity jobs may only cause it to push the speed up to 75%, not 100%. |
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