Linux Optimization

I have been traveling the last two weeks, and I have found how useful is wifi-radar on my Linux powered laptop.

I have an IBM Thinkpad T30 with an Aironet Wifi internal card (for the records)

Introduction

iftop is a real good utility both for your own PC/Laptop and for your server and specially good for the latter and even better if this server is acting as the main router in your premises.

sysstat is a package of monitoring tools, these are the tools included in the package.

iostat

Reports CPU statistics and input/output statistics for devices, partitions and network filesystems.

mpstat

Reports individual or combined processor related statistics.

pidstat

Reports statistics for Linux tasks (processes) : I/O, CPU, memory, etc.

sar

Collects, reports and saves system activity information (CPU, memory, disks, interrupts, network interfaces, TTY, kernel tables,etc.)

sadc

One important thing to check on your Linux box, is the CPU utilization, specially if usually compile software, or if you have server applications running on your PC.

One good tool to check this is: htop, which will show you a lot of useful information, the important data is the load average, that will show you if you are having processes waiting for the CPU or not.

How to assign and reassign priority to Linux commands or processes, to optimize your CPU ussage

You may have seen this problem with your Linux sometimes, you are working with your normal applications, like browsing the web, using Open Office or any other thing, and then Linux start a cron process or you start a make command, and all the other applications slow down.

Well you can solve that by entering different priorities to different applications, this is done with the nice and renice commands.

If you have read my post about Installing personal web server and you have installed it, you may be now enjoying its benefits but now it is maybe time to tweak it a little, specially the way it purges files and maintain the cache size in the disk.

Update

Check the part II of these article, boost your internet connection II

Some days ago while I was on a business trip, and trying to work in the Hotel, the second day the Internet connection was really slow, (maybe some other guest was downloading a lot of information), while trying to look for some information on the web, it took lots of seconds to even get the IP of the pages I was trying to visit.

I decided that I needed a local DNS on my PC to improve at least a little my speed experience.

I have been trying to find the performance differences between a swap partition and a swap file in Linux.

I have found several affirmations that swap partitions are better, but lots also say they are the same (at least for kernels 2.6).

I can find some differences that can help you make the good choice, or when to use swap on file or partition.

1. The problem

You have limited bandwidth, which you need to share with some others or just between different services on you PC.
So you need a tool that can shape, control and manage the bandwidth so everybody can make a responsible use of it.

Swap Memory is a space in the Hard Disk of your computer that Operating Systems (Linux in our case) will use to put the info that is actually on the RAM to free it for another application.

This should be done when the system needs memory for a new process and there is none, so we can see that if our system has plenty of RAM it will maybe need no SWAP memory.

The use of the swap memory by default on Kernel 2.6.xx is set to 60% that means that the system will use intensively the swap memory, this is good if we have a small amount of memory and lot of load on our PC or server, but if we have plenty of RAM or we are using a Desktop machine, we maybe do not need this setting, let's see how to change it.