Showing posts from September, 2012

Julia - Parallel Programming Made Easy

I always liked the name Julia but now we have a nice new parallel programming language with that very name.

The Julia Programming language is a parallel computing model that works across multiple cores and cluster nodes.

To read more

Performance Testing Across Regions

Just recently I needed to perform some load / stress testing on a web application hosted on the east coast of america.

I had a number of dedicated test boxes around Ireland and the UK

but I was concerned that the geographic distance may be playing a part in the results I was seeing

So I needed to get a server in the US from which I could launch similar tests.

M-Net is a public-access UNIX system based in Ann Arbor, Michigan, owned by Arbornet

You can telnet in to, login with newuser, no password, and it will allow you setup a username with password on a free bsd shell

Great idea. It allowed me perform performance tests on my web app on the east coast from mid western US.

Monitor Ubuntu with sysstat

Installing sysstat on Ubuntu

1. Install
apt-get install sysstat

2. Enable collection of system performance data
vi /etc/default/sysstat
set “ENABLED” to “true”.

3. Start the sysstat service
/etc/init.d/sysstat start

4. Take a look at performance data every 10 minutes.

If you'd like to change the interval (every 10 minutes) by which sysstat collects data.  You can change the interval by editing /etc/cron.d/sysstat
# Activity reports every 10 minutes everyday 5-55/10 * * * * root command -v debian-sa1 > /dev/null && debian-sa1 1 1
# Activity reports every 5 minutes everyday 5-55/5 * * * * root command -v debian-sa1 > /dev/null && debian-sa1 1 1