Wednesday, 3 December 2014

The "Uncanny Valley" of L3 Cache Contention

While preparing for my talk at QCon SF 2014, I wanted to investigate a theory around how micro-benchmarks are not a useful reflection of how software may behave when run as part of a larger application.  Specifically due contention in the last-level cache (L3* in current Intel CPUs).

Wednesday, 29 January 2014

Linux Alternatives and Oracle Java

If, like me, you prefer to run the Oracle version of Java on your Linux machine as the default JDK, you will often find that the Linux distro will have other ideas.  Fedora for example has a number of Java based applications as part of the distribution which will include a dependency on the OpenJDK.  When the distro installs OpenJDK is will generally be setup as the default for executing the various Java binaries (e.g. 'java', 'javac').  However, the team at Redhat built a system called alternatives which maintains a set of symbolic links that allows the user to switch between multiple implementations of a package the supports the same functionality.  I've managed to understand enough about the alternatives package that I can now easily switch between the Oracle JDK and the OpenJDK.