LHC@Home Status/Plans, 7th August 2012

[Free-DC]

First, many thanks for your continued support. From my/CERN side all has been running rather well and I am submerged by results.I now need to take some time to analyse them. In particular to decide between the two methods of computing the beam - beam effect.Then I shall probably submit several studies to do an intensity scan where I study the beam - beam effect depending on the size, and hence charge, of the accelerated bunch of particles.At the same time, I must finish the documentation of the "user"infrastructure so that my colleagues may easily use BOINC as they return from vacation. In addition I want to set up a dedicated "user" system "lxtrack" in order to provide disk space here and to try and keep up with the results as they are returned.I have to look at the Deadline problem for 10**7 turn jobs.I set a bound of 30 days for any WU....need to discuss with Igor is that is NOT what you see at home. Of course we really want a low bound to get results back quickly, but I also want to use older slower systems. We shall have to work out some sort of compromise. My attempt as 10**7 turns was probably a bit over the top, but I was keen to try it.We hope/expect to produce a valid MAC executable this week. I also need to add some new "physics", new elements, to Sixtrack as provided by a colleague. (Also need to add modifications for "Collimation" but they are not relevant to BOINC.)The next version should also support SSE4.1.I was very pleasantly surprised to win an NVIDIA TESLA C2075.The catch is that I have to use it and program it with OpenACC. There will doubtless be some hiccups intsalling the board and the necessary(PGI) software. I shall in fact try my "Tomography" application which already runs in parallel using HPF or openMP. If that works I shall seriously consider a multi-threaded Sixtrack (using GPUs or not) by tracking many more particles in each Work Unit. Non-trivial but rather exciting. I am just at the ideas stage here, but.....it would of course use multiple threads on a multiple core PC as well. A dream?Finally, I have to take time to publish my work on floating-point portability and reproducibility. I believe I might be the only person who gets identical bit for bit 0 ULP different results after many Gigaflops with 5 different Fortran compilers at different levels of optimisation.

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