Ruby on Rails

I though lets give Ruby on Rails another go. During my first encounter with Rails I had to develop in a already huge code base.

Starting from scratch and with a simple app is the way to go imo when learning a new stack.

Beside the great tutorials on the Rails website I came across this online book from author Michael Hartl called Rails tutorial.

His book takes you from zero to hero in 14 steps.

FreeBSD memory counters explained

Ever wondered what the different memory indicators in top mean?

Allan Jude give this nice explaination:

  • Active: Memory currently being used by a process
  • Inactive: Memory that has been freed but is still cached since it may be used again. If more Free memory is required, this memory can be cleared and become free. This memory is not cleared before it is needed, because “free memory is wasted memory”, it doesn’t cost anything to keep the old data around in case it is needed again.
  • Laundry: Number of dirty bytes queued for laundering.
  • Wired: Memory in use by the Kernel. This memory cannot be swapped out
  • Cache: Memory being used to cache data, can be freed immediately if required
  • Buffers: Disk cache
  • Free: Memory that is completely free and ready to use. Inactive, Cache and Buffers can become free if they are cleaned up.

So, you can just add Inactive to your Free count and consider it unused. Wired is memory in use by the kernel, which includes the networking stack. running netstat -m will give you a summary of memory usage by the network stack.

For more information please check the FreeBSD wiki page which gives a more detailed explanation.