Topic revisited -- CPU frequency/scaling with Linux

Message boards : Number crunching : Topic revisited -- CPU frequency/scaling with Linux
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Profile michael37
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Message 665824 - Posted: 24 Oct 2007, 18:58:46 UTC

Some users running Seti on their notebooks observed that their CPU clock speed reduced to the lowest. This happens because, under some conditions, Linux does not consider 'nice' (aka low priority) processes as CPU load. This happens even if the notebook is plugged in the AC.

This is a great compromise for less heat+longevity of your notebook vs raw crunching power.

Note: this works only for newer versions of Linux.

cd /sys/devices/system/cpu/cpu0/cpufreq/ondemand
more ignore_nice_load

If this is set to 1, then your CPU speed will scale down when runnig Seti only.

If this is set to 0, then you CPU will run at full speed when running Seti.

You can change this value right there, but it won't persist through reboots.

How to change it for gnome-based systems:



Run
gconf-editor
go to /apps/gnome-power-manager/cpufreq
check box consider_nice.

Takes effect immediately.

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Message 665891 - Posted: 24 Oct 2007, 22:40:09 UTC - in response to Message 665824.  
Last modified: 24 Oct 2007, 22:40:55 UTC

Thanks, I actually had that problem with a C2D desktop - on niced loads it always downclocked. I got around it by disabling EIST etc in the BIOS, since this PC was always *meant* to be running at 100% anyway.

However, especially for a laptop, you'd want that functionality, and a software change is probably a bit less drastic.

Annoying that it doesn't persist, though.
Crunching SETI@Home as a member of the Whirlpool BOINC Teams
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Profile michael37
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Message 689001 - Posted: 5 Dec 2007, 20:52:21 UTC

I wasn't quite clear -- if you have a Gnome based system, the setting is managed by Gnome and persists through reboots.

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Message 689011 - Posted: 5 Dec 2007, 21:33:48 UTC - in response to Message 689001.  

I wasn't quite clear -- if you have a Gnome based system, the setting is managed by Gnome and persists through reboots.


It requires to load the gnome-power-manager at startup too. This might not be the default setting in some distributions.
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Message boards : Number crunching : Topic revisited -- CPU frequency/scaling with Linux


 
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