Thursday, 30 April 2015

Debian Jesse 8.0 is launched!

The new stable distribution of Debian - version 8, (codenamed jessie) has just been released on April 25th, 2015.

For many Linux Power Users Debian is the most important Linux distribution. From it springs such popular Linux distributions as Mint and Ubuntu. It's not that well known to non-power users because it's purely a community operating system which means that there is no company behind it, as there is with Red Hat and CentOS, Fedora, and Red Hat Enterprise Linux (RHEL). However, Debian is more than just the foundation for other better known Linux distros, it is a powerful desktop and server Linux in its own right.

If you wondered Jessie is named afer the Cow Girl in Toy Story,

Friday, 10 April 2015

Numbers that every computer engineer should know.



  • L1 cache reference: 0.5 ns
  • Branch mispredict: 5 ns
  • L2 cache reference: 7 ns
  • Mutex lock/unlock: 100 ns
  • Main memory reference: 100 ns
  • Compress 1K bytes with Zippy: 10,000 ns
  • Send 2K bytes over 1 Gbps network: 20,000 ns
  • Read 1 MB sequentially from memory: 250,000 ns
  • Round trip within same datacenter: 500,000 ns
  • Disk seek: 10,000,000 ns
  • Read 1 MB sequentially from network: 10,000,000 ns
  • Read 1 MB sequentially from disk: 30,000,000 ns
  • Greatest latency that appears real-time for interactive UI: 100,000,000 ns
  • Greatest latency that appears real-time for query based UI: 250,000,000 ns
  • Send packet CA->Netherlands->CA: 150,000,000 ns