Los Alamos National Lab has retained its spot atop the list of the TOP500 supercomputer sites. The Roadrunner supercomputer was completed a year ago, in June of 2008, and has held the top slot in the bi-yearly rankings since then.

The computer, according to a press release from the TOP500, is still “one of the most energy efficient systems on the TOP500.”

The computer was the first computer to break the petaflop/s Linpack — quadrillions of floating point operations per second — barrier.

The Encanto supercomputer, which is located at the Rio Rancho Intel plant, was ranked the 3rd fastest supercomputer in the world in November’s rankings. It has fallen to 17th in this edition of the rankings.

As for who compiles the list:

The TOP500 list is compiled by Hans Meuer of the University of Mannheim, Germany; Erich Strohmaier and Horst Simon of NERSC/Lawrence Berkeley National Laboratory; and Jack Dongarra of the University of Tennessee, Knoxville.