Performance shock

Tom Adelstein adelste at
Sun May 1 16:39:08 UTC 2005

> With all that aside, I understood everything you posted about
> ways to make performance improvements except for swapiness.  What
> precisely is 'swapiness' and where is it set?

First, forgive my typos from the last email. The time was late and I was
very tired. I didn't even read the post before sending it. When I read
it this morning, I sounded drunk. 

Niran Babalola wrote an interesting email about swappiness. I learned
about it on other forums. Here's Nirans post:

> One thing I noticed in Warty was that the kernel was swapping out
> things that I needed far too often. To fix this, I lowered the
> kernel's swappiness setting, which tells it how aggressively to
> swapunused data in memory. The default is 60 I think, and turning it
> down to 10 or 20 made my system more responsive. If you want to try
> this, here's how, but try not to break your computer.
> $ sudo sysctl -w vm.swappiness=10
> That will lower the swappiness for your current session, but when you
> reboot it will go back to the initial value. If you want to use it
> permanently, add:
> vm.swappiness=10
> to your /etc/sysctl.conf. In Hoary, the default swappiness has been
> working well for me. If you end up changing this, you should probably
> Google for swappiness so you can read about why it's a good thing and
> why, in theory, you don't want to lower it. I guess it's had some
> kinks worked out of it since the Warty kernel version, so now I agree
> with it.

I ran the command $ sudo cat /proc/sys/vm/swappiness

and found the setting at 60.

I then ran $ sudo sysctl -w vm.swappiness=10 and ran can command again
and it registered 10.

I added adding vm.swappiness=10 to /etc/sysctl.conf

I put it on the last line. No comments existed for that entry so it
looks naked in the config file.

I also suggest keeping your swap partition the same size as your RAM. 

My OOo writer is ready to run in less than ten seconds. But I have
enough memory to pass off for cache. Shutting down the swap access helps
me because everything seems to happen in RAM now. 

On your intel video card, make sure you have the correct driver. I would
also change the color resolution to see which on works best. I have a
Flat Panel monitor and sometimes it runs faster with 24 bit color. I
don't know why and that seems counter intuitive.

IMHO, you won't benefit from much from the openoffice changes because of
the RAM limitations. Essentially, you can run out of RAM and the system
will do back and use swap again. That defeats the exercise.

A couple of other things that I have found to work: 1. Use a static IP
address and don't use dhcp. In Linux dhcp runs the server and client
side. In Windows they only run the client side.

If you know how to recompile your kernel, get rid of everything you
don't need for your particular machine. You should have the hardware
profile. You might also want to trade things like iptables and other
security items to enhance performance. Make the kernel as lean as

I use gnome. I remove anything that I won't use - especially
administrative gui programs. I do my administrative tasks from the
command line.

Also, remove all your openoffice filters and programs you don't use.
Also, change that setting from 128 MB to 64 and then 32 to see if those
setting improve performance. 

256 MBs of RAM can be sufficient for Linux. Unfortunately, in order to
appeal to novice users, we have put a lot of things into Linux that we
did not have five years ago when we could run web servers with 32 MBs of
RAM on the 2.0.35 kernel. 

Let me know how it goes. I'll have more items to suggest soon.


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