Possible Fix to HIGH CPU USAGE in 686 SMP Kernels!

[barakaspeed]

I have been plagued since my install of ubuntu 6.06 with excessively high idle cpu usage running the 686 kernel. It was the one installed by default during installation for my Pentium M 1.6Ghz. The culprit usually was Xorg hogging over 35% of cpu power during idle. You can follow my other thread where I ended up installing the 386 kernel as a work-around: http://www.ubuntuforums.org/showthread.php?t=192207

A MUCH better work-around was offered by sohail (All credit for this goes to him) in this Bug Report I was following: https://launchpad.net/distros/ubuntu....15/+bug/30570

This is what he wrote from there:

Guys, have you tried adding this to /etc/rc.local: echo 1 > /sys/module/processor/parameters/max_cstate This is what you should do if you want to use a 686 kernel. Of course, I wish someone would revert the ubuntu patch that *caused* this in the first place...

Now I'd be the first to admit I'm no Linux Guru. My educated guess the problem is solely in SMP support in the 686 kernel being enabled for processors that have no need for it. (aka my Pentium M)

Anyways, I'm glad I can run the 686 kernel on my laptop with less cpu usage and cooler (The fans were kicking on all the time before this)

Thanks to the great community

[Patrick-Ruff]

good job, nice find/research.

[no1wantdthisname]

Wow, thanks. I've been trying to figure out why cpu load was so high since the beginning of dapper development when SMP support was included by default in the 686 kernel.

[jerinjoy]

I installed the i386 version of dapper drake on my Pentium M 1.6Ghz machine. Should I upgrade to the i686 kernel version? Any advantage in doing so?

[GadgetsGuy]

how do we add this extra line

what would be the command, as I am still not up to speed with permissions

thanx
GG

[barakaspeed]

jerinjoy, to be completely honest, I have not seen any advantages yet. I play games, videos, and such on my machine and haven't noticed much of a difference between 386 and 686. Though having the 686 modded to work properly gives me that piece of mind that my laptop is running at it's most optimal configuration. I'm probably just crazy for thinking that way..

GadgetsGuy:

sudo gedit /etc/rc.local

and insert this line into that file. I placed it the line above exit 0.

echo 1 > /sys/module/processor/parameters/max_cstate

Here's my modified rc.local file now:

#!/bin/sh -e
#
# rc.local
#
# This script is executed at the end of each multiuser runlevel.
# Make sure that the script will "exit 0" on success or any other
# value on error.
#
# In order to enable or disable this script just change the execution
# bits.
#
# By default this script does nothing.

echo 1 > /sys/module/processor/parameters/max_cstate
exit 0

[GadgetsGuy]

OK ... I have done this, and rebooted, yet my hard drive is still spinning non-stop

any other ideas?

I am getting very frustrated by this, and Ubuntu 6.06 (686) was working like a charm until 2 days ago, and quite frankly, if I can not figure this out soon, I will have to go back to Win2000 Pro while I still have a hard drive !!!

[barakaspeed]

have you tried the 386 kernel to see if that helps/changes anything?

[t0mc4t]

Sorry if little bit out of topic. But how do we change the kernel that we used? I mean from 386 to 686 or 686 to 386. And how do we check the kernel that we are currently used?
Thanks...

[veratyr]

I'm using XGL with a 686 kernel (has smp support built in now?) and I havn't had any problems with high cpu usage? Granted my P4 is reasonably fast at 3.0GHz.

As for installing a 686 kernel. Open up synaptic and search for "linux-image" and you should find what you are looking for. You may need to install the restricted modules for 3d driver support for whatever kernel you choose to install. Search for "linux-restricted" and install the corresponding modules. Grub usually displays what kernel you are booting to.

*shrug*