CPU usage constantly 100% (Solved)

[SO•Audiojack]

I have this Acer Aspire 1640Z laptop which I got for free a long while ago. It had Windows XP Professional installed but I removed it because it took literally an hour to boot and crashed every time I tried to open a web browser.

So I installed Xubuntu Linux (12.04 if I remember correctly) and was happy for a while. BUT even this seemed very slow to me and kept hanging up constantly when using Facebook or some other regular web applications.

SO I did a complete format and installed Lubuntu 13.04, which is a lot faster already. I can work with this. But I did notice now (I didn't even really bother to check with the other OS's) that my CPU usage is usually almost 100% and always +70%. This is a bit off the scale I think. So what should I do? I'm not a big Linux expert. The computer seems to work okay now with Lubuntu but occasionally my Chromium tabs crash randomly and the Ubuntu repository seems to crash on startup. (Lubuntu's own repo works tho)

This computer has an Intel Pentium M 735 processor, other information can be found here: http://www.miniputer.com/Acer/Aspire_1640Z.html

At first I thought I was lacking RAM but it seems that I'm only using about 200-300mb so I don't think that's what keeps crashing my browser tabs...

[[TC]»Pete«]

One question, why Lubuntu?

[SO•Audiojack]

(2013-10-11 21:33)Lampshade Wrote:  One question, why Lubuntu?

Because LXDE is light and because I'm a Linux nub and wanted a common and simple platform.

[[TC]►Frozen◄]

Were you using that 300MB RAM with google chrome opened or not?

[SO•Audiojack]

(2013-10-12 08:01)Frozen Wrote:  Were you using that 300MB RAM with google chrome opened or not?

With Youtube and other tabs open in Chromium, about 380mb is used constantly. Lubuntu uses way less than that.

[Zipppy]

I'm thinking the processor could be in a lower clock speed than stock. I have a netbook with an Intel Atom, that's rated lower than this CPU (also runs at a lower clock speed), and I have no usage issues.

[SO•Audiojack]

Not sure how this works but I threw in a 2gb RAM stick and the problem seems to be gone. The computer is now using massively more RAM than before though (before it was like 245 out of 498mb and now it stays at 728 out of 2007mb) but the CPU usage dropped to 30-50% from 70-100%... So I guess (hope) this is solved.

I was thinking that maybe Ubuntu was trying to use CPU power to compensate for lack of RAM, as in organizing the cache files et cetera to be as efficient as possible at all times, and it simply couldn't do that well enough without occasionally freezing...? Just a hunch.

[[TC]►Frozen◄]

Thats a good point. Having lack of ram makes your cpu overclock in case neither your ram or cpu can handle all the processes running in your computer

[SO•Audiojack]

For others who might face this problem, I studied the issue somewhat and it will also help to decrease the swappiness of the system:

Type in terminal: gksudo leafpad /etc/sysctl.conf
If you don't have Leafpad, then replace that with some other text editor...

Then input this at the end of the file:

vm.swappiness=10
vm.vfs_cache_pressure=50

The default swappiness is 60 which is way overkill for a regular system... I read that 5-10 (for less RAM a smaller number) is good.
The second line improves cache management.


Just a FYI

E: After checking out how the system works now... It's very good.
I started at 100% processor usage, which dropped to 50ish after installing more RAM memory. After I did the swappiness trick the processor usage dropped to 1. Yes, 1 percent.