OpenMP, ccNUMA and C++
If you are interested in programming with C++ and OpenMP, the just-finished diploma thesis of Holger Stengel might be interesting for you (in German – available on request). It studies ccNUMA effects in C++ and ways to circumvent them. To fuel your appetite, there is a nice English poster with most of the results: poster_cppnuma.pdf
This whole work was kicked off by some of the problems I had encountered during my PhD thesis where I had parallelized a C++ code from condensed matter physics. At that time, nobody had even thought about what would happen if standard C++ elements (arrays of objects,
std::vector<> etc.) were used on a ccNUMA machine with OpenMP. Another inspiration came from Matt Austern‘s article about Segmented Iterators and Hierarchical Algorithms. The segmented iterator described in this paper could by useful for many purposes, of which NUMA placement is only one. In the thesis we implemented a version in which you could exactly control data placement by configurable padding.
I would be glad to continue on this topic with another diploma/bachelor/masters student. If you are hooked, feel free to contact me.
It would be great if average engineers could write code to use NUMA machines fairly efficiently. You guys are making that more feasible .. so good work. I particularly appreciate that your efforts also apply to Fortran .. a bit simpler to write in ..