Re: CPU default frequency is at 75%

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Jochen Schulz <ml@xxxxxxxxxxxxxxxx> writes:

Merciadri Luca:
Jochen Schulz <ml@xxxxxxxxxxxxxxxx> writes:

What does

# cat /sys/devices/system/cpu/cpu0/cpufreq/scaling_governor

say after bootup?

Ondemand, the same as what appears in the applet, after boot. However,
despite "Ondemand", even a huge CPU load does not make Debian asking
for more CPU resources, such as 100%.

Then have a look at
/sys/devices/system/cpu/cpu0/cpufreq/scaling_max_freq

It should contain the highest frequency your processor supports.
It is the case.
That would be the kernel's default behaviour if your
current governor is either ondemand or conservative.

How could I modify it?

Modify what? -Most probably, cpufrequtils will contain all the tools
you need. It allows you to select a governor and set min/max frequency
limits, for cases where they are mis-reported by default.

I suggest you use just the ondemand governor and stop caring about the
issue at all. You will get full CPU power when you need it and save a
little power when you don't.

My aim is not to save power. I am running many scientific-purpose
applications, and they need full CPU power.

Sure, no problem. The ondemand governor is all about saving power
without sacrificing performance. If nothing's wrong with your
configuration, this is exactly what you should get by default.
Something must be wrong, as CPU freq. is never modified, even with
there is a huge load.
A question that comes to my mind: how do you measure the current clock
frequency? Only by looking at the Gnome applet?
On one hand, by looking at the GNOME applet. On the other hand, by
hearing fans, which are really noisy when I use "Performance" rather
than "Ondemand".
I would take a look into
/sys/devices/system/cpu/cpu0/cpufreq/scaling_cur_freq, just to be
sure.
It exactly gives the same values as GNOME's applet does.
- --
Merciadri Luca
See http://www.student.montefiore.ulg.ac.be/~merciadri/
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