[SOLVED] How to disable cpu throttling in slackware 13?

Laevatain · 05-07-2010, 01:53 AM

I'm trying to install ATLAS which requires disabling cpu throttling.
Normally one can do it in the BIOS, while there isn't such an option of my dell inspiron 6400. Actually there is a SpeedStep option in the BIOS, however, you cannot get the highest but the lowest performance by disabling it (dell!!!).

After googled a lot, I found in some distros, there is a /usr/bin/cpufreq-selector through which one can disable throttling. But it doesn't exists in slackware.

I known that by appending kernel option "acpi=off", one can disable the whole acpi and thus the throttling control in slackware, but it seems so dirty.

Anyone known a better way to do it?

ps: With a intel T2050 cpu, i didn't find the directory /sys/devices/system/cpu1, but only the /sys/devices/system/cpu0.
Similar case in /etc/acpi.
it seems that slackware treats my cpu as a single core one, while it is not.

Daedra · 05-07-2010, 02:05 AM

Ignore, Use info below

nivieru · 05-07-2010, 02:30 AM

in /etc/rc.d/rc.modules/ :

Quote:

### CPU frequency scaling support
#
# Below, set CPUFREQ to enable CPU frequency scaling to save system power.
#
# To always try to use CPU frequency scaling, set to: on
# To never use CPU frequency scaling, set to: off
# To use it only when the battery module is loaded (this will cause it to
# be used by default with most laptops), set to: battery
#

CPUFREQ=battery

so you should change it to

Quote:

### CPU frequency scaling support
#
# Below, set CPUFREQ to enable CPU frequency scaling to save system power.
#
# To always try to use CPU frequency scaling, set to: on
# To never use CPU frequency scaling, set to: off
# To use it only when the battery module is loaded (this will cause it to
# be used by default with most laptops), set to: battery
#

CPUFREQ=off

tuxdev · 05-07-2010, 03:15 AM

Whatever ATLAS is, it really has no business requiring that cpu throttling is off.

Laevatain · 05-07-2010, 06:03 AM

Quote:

Originally Posted by nivieru

in /etc/rc.d/rc.modules/ :

so you should change it to

thank you, nivieru

but not work... sad.

Code:

bash-3.1# cat /proc/acpi/processor/CPU0/info 
processor id:            0
acpi id:                 0
bus mastering control:   yes
power management:        yes
throttling control:      yes
limit interface:         yes

and for ATLAS config:

Code:

CPU Throttling apparently enabled!
It appears you have cpu throttling enabled, which makes timings
unreliable and an ATLAS install nonsensical.  Aborting.
See ATLAS/INSTALL.txt for further information
xconfig exited with 1

Laevatain · 05-07-2010, 06:20 AM

Quote:

Originally Posted by tuxdev

Whatever ATLAS is, it really has no business requiring that cpu throttling is off.

sorry, tuxdev, I have to. ATLAS achieves optimal linear algebra operations by providing machine-specific libraries. It is needed by a lot of mathematical software.

"CPU throttling makes pretty much all timings completely random, and so any ATLAS install will be junk. " --from atlas website

damgar · 05-07-2010, 08:21 AM

After you changed the option to "no" did you reboot the machine? Just changing the option in the script probably won't be enough. A reboot then is probably necessary.

nivieru · 05-07-2010, 08:29 AM

well, assuming you didn't reboot, changing the rc.modules script won't stop the cpu scaling since the modules are already loaded.
to stop it you need to manually unload the modules.

the change in the script should work from next boot.

or you could undo the previous change and instead change (just below in the same file) :

Quote:

### CPU scaling governor:
#
# Set the default scaling_governor to be used (such as userspace or ondemand)
# if there is a CPUFreq scaling policy module loaded that supports it:
SCALING_GOVERNOR=ondemand

to

Quote:

SCALING_GOVERNOR=performance

than execute the script

Laevatain · 05-07-2010, 12:29 PM

Quote:

Originally Posted by damgar

After you changed the option to "no" did you reboot the machine? Just changing the option in the script probably won't be enough. A reboot then is probably necessary.

yes, i have rebooted, not work

Laevatain · 05-07-2010, 12:30 PM

Quote:

Originally Posted by nivieru

well, assuming you didn't reboot, changing the rc.modules script won't stop the cpu scaling since the modules are already loaded.
to stop it you need to manually unload the modules.

the change in the script should work from next boot.

or you could undo the previous change and instead change (just below in the same file) :

to

than execute the script

thx man, i'll try it.

Laevatain · 05-07-2010, 12:58 PM

Quote:

Originally Posted by nivieru

well, assuming you didn't reboot, changing the rc.modules script won't stop the cpu scaling since the modules are already loaded.
to stop it you need to manually unload the modules.

the change in the script should work from next boot.

or you could undo the previous change and instead change (just below in the same file) :

to

than execute the script

again, not work...

dive · 05-07-2010, 01:20 PM

Why not rmmod acpi_cpufreq and blacklist it.

nivieru · 05-07-2010, 01:21 PM

what's the output of

Quote:

cat /proc/cpuinfo | grep Hz

?

tuxdev · 05-07-2010, 05:15 PM

Quote:

"CPU throttling makes pretty much all timings completely random, and so any ATLAS install will be junk. " --from atlas website

It depends somewhat on which governor you use, but if you use the race-to-idle governor as recommended by the kernel devs, the timings should not be "junk" at all.

Laevatain · 05-07-2010, 08:19 PM

Quote:

Originally Posted by nivieru

what's the output of
?

...

Code:

bash-3.1# cat /proc/cpuinfo | grep Hz
model name	: Genuine Intel(R) CPU           T2050  @ 1.60GHz
cpu MHz		: 800.000