Georg Hager's Blog

Random thoughts on High Performance Computing


Christie Alappat comes second place in ACM Student Research Competition Grand Finals

Our PhD student Christie Louis Alappat, by winning the ACM Student Research Competition (SRC) at SC18 at the graduate level last year, has advanced to the ACM SRC Grand Finals, where the winners from 26 ACM conferences contend for the Grand Prize. For this last round he had to prepare a five-page paper about his research. This paper, and the whole body of his work, was evaluated again by a panel of judges.

We are now happy to announce that Christie has come second place in the Grand SRC Finale. Together with his advisor, Prof. Gerhard Wellein, he is invited to the awards ceremony which will take place in San Francisco on June 15. This is the very same ceremony at which Yoshua Bengio, Geoffrey Hinton, and Yann LeCun will receive the prestigious ACM Turing Award 2018 for their seminal work on deep learning algorithms. Talk about good company!

Christie’s research revolves around a long-standing problem in computer science: How must a graph be colored to enable parallel processing in the presence of dependencies? His solution, the “Recursive Algebraic Coloring Engine,” can be used to parallelize many sparse algorithms in a hardware-efficient way, taking the specific properties of modern multicore chips into account. It outperforms existing approaches and libraries by a significant margin at such an important operation as symmetric sparse matrix-vector multiplication (SymmSpMV), but its range of applicability is much broader. Christie has prepared a walk-through of his SC18 poster to explain the details:



Christie Louis Alappat wins the SC18 ACM Student Research Competition Award

Picture (c) SC Conference. Used with permission.

Our PhD student Christie Louis Alappat just took first place in the ACM Student Research Competition at SC18. His work revolved around the “Recursive Algebraic Coloring Engine,” which is a new method and library for hardware-efficient graph coloring. This means that he will advance to the grand finale next year. Congratulations!

Christie’s project is part of the activities in ESSEX-II, a project funded by the German Science Foundation (DFG) within the priority programme SPPEXA.

As part of the competition, Christie has prepared a video with details about his work:


Intel Threading Building Blocks (TBB 2.0) on RRZE systems

Intel Threading Building Blocks (TBB 2.0) on RRZE systems
On Woody and Altix the current version of Intel’s TBB library is now installed. TBB is a C++ framework for shared-memory parallel programming. If you are fed up with marrying C++ and OpenMP, TBB might be the right choice. Use it by loading the tbb/2.0 or tbb/2.0-debug modules, respectively. On Cluster32 you can access the modules from Woody by typing, e.g., module use /apps/modules/modulefiles/libraries, but remember that we have only provided a 64 bit version. The library was compiled with the Intel compiler and we don’t guarantee that it will work with anything else. Documentation can be found on the TBB website:

We are very much interested in sharing experiences with all users of the library. So please if you have comments or questions, contact hpc@rrze.

Sun SPARC Enterprise T5120 at RRZE

As of this week we are proud owners of an UltraSPARC T2 system (1 socket @ 8 cores, 32 GB, 1.2 GHz). This one is a little slower than the 1.4 GHz machine we had access to at RWTH Aachen, but the characteristics are quite the same. After some intensive benchmarking, this machine will be made available in our test cluster for all HPC users to evaluate.