how to diagnose computer slowing down problem
 

This is a hp pavilion zv5120us, 100GB hdd, 1GB RAM, Ati Radeon Mobility 9000 IGP (using open source ati driver), Intel Celeron 2.8GHz. I have up-to-date Ubuntu 5.10 now for about 5 months installed to this.

Quickly to the question: What are the common steps to diagnose why a computer will slow down with time in Linux?

More info: in the last months, I felt a decrease on overall desktop system responsiveness. Firefox waits a second or two before getting my mouse click such as switching to other tabs and so on, OpenOffice and Liferea does the same thing. And, well, that's all I use... Qemu is slow, naturally, and Calculator is fine ;) Yesterday, I booted from the live cd for a rootkit scan, and the live system was much faster than my installation (although it's not supposed to be).

Possible culprits: I suspect either a wrong configuration or a bug in the video drivers, or a bug or wrong configuration on CPU usage (cpu does not support any configuration though, such as throttling and so on; and powernowd doesn't work with this one). It looks like CPU doesn't know how much it will work for the programs: launching Internet Explorer or loading pages with it in qemu takes 100% CPU, Firefox eats 50-70% CPU (and sometimes 100%)... The file system fragmentation may be? 1% in / and 8-12% in /home.

What are your thoughts? Any output you'd like? Thanks a lot.

You can use the "top" command to show which processes are currently eating up the most CPU.
A single buggy daemon could be eating up a ton of your CPU power, slowing everything else down.

every application that is doing some processing on the desktop (as opposed to the background applications) eat cpu during the time they are processing. So if firefox is loading a (especially javascripted or multimedia) page, it will eat the most (50-80%), if OOo is doing stuff, it will eat that cpu etc. No constant variable... except doing a process and having access to cpu?

What other steps would you reccommend?

bumping this

gtk? cairo?
 

can what I'm experiencing be related to this: http://ubuntuforums.org/showthread.php?p=792816

Although mine is also related to time spent using OS.

1. I would probably start looking at whatever programs I'd installed since starting to experience the slowdown, and uninstall them and see if I couldn't identify one of those as the culprit.

2. A slowdown might be a physical memory problem? Check eg vmstat - I'm not sure how to interpret the output (google).

3. Disable any unneeded deamons (sendmail etc).

4. Are you quite sure your cpu does not support some type of frequency scaling - check google? If so you might have somehow developed a problem with that. What does cat /proc/cpu say your speed is while doing cpu-intensive tasks (eg ripping a dvd) - it should move into top gear.

Cpu scaling won't work unless the appropriate module is loaded (unless it is already compiled into the kernel- not sure what Ubuntu does). Assuming the cpufreq daemon is running, does

# modprobe cpufreq_ondemand
# echo "ondemand" >/sys/devices/system/cpu/cpu0/cpufreq/scaling_governor

make any difference?

Powernowd won't work unless the scaling_governor is set to "userspace".

5. Gnome and KDE are notoriously sluggish in any case (the coming new version of kde is supposedly going to be leaner and faster). I'm considering ditching these fat bloated cows in favour of eg fluxbox.

Another typical problem is: do you have DMA enabled on your drive? Check to check/set it.

@woofdef
1. I only install packages from the ubuntu repos. except firefox 1.5 that I just extracted to /opt/firefox (bc. it is far more usable than the one that comes with ubuntu). I'd prefer to skip this step if it's okay for you).

2. I had troubles understanding the output of vmstat, but I'll try the memory test during my next boot (wouldn't that check for physical memory problems?)

3. done bf this started to happen

4. as far as I know (and powernowd reports -tried it a while ago using an ubuntu forum howto-), this cpu doesn't support scaling. the frequency seems to be at 2.8GHz at all times.

5. I tried xfce4 (from ubuntu repositories, called xubuntu-desktop) and fluxbox (latest version compiled from source). fluxbox is fast as it is supposed to be (but I need more time with it), xfce4 is slow when it is drawing stuff (open xfce menu, firefox, like in gnome, small hangs of 0.5 - 1 second), which makes me even more suspicious abut that gtk / cairo link I posted previously. the post says that ubuntu switched to cairo too early as an investment. in that case, I wouldn't have any hopes but to change the distro (but winmodem doesn't work with anything else :cry: ) or maybe wait for the new version (which I plan to install anyway).

@scuzzman

hdram says dma is enabled on this hard disk. the problem seems to be related to cpu usage (or gtk? cairo? X? video drivers?) though.

PS. I just changed my xorg.conf from ati to radeon with a couple of options enabled. fps increased according to glxgears (by ~200-300) on the average, but sluggishness is still there.