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Started by BF, June 09, 2009, 01:43:00 AM
QuoteHi all,The new and improved abc finder application (previous announcement) is ready for testing! We would really appreciate if you could help test it. Hopefully the testing will not take long, since the new client is basically the well-tested old abc@home client code with a new algorithm inserted.Right now we have win32, linux i686 and linux x86_64 binaries available. Mac OS X and win64 binaries will follow as soon as we have build machines for those platforms set up again, hopefully still in time for the tests.Since our old abcbeta machine has sadly died completely, I have set up a new (very basically configured) project with about 850 randomly selected new workunits and a quorum of two results per workunit. The URL to attach to is:http://abctest.math.leidenuniv.nl/abcbeta/Please let me know of any issues you encounter, or things you think could be improved. I'll be online most of tomorrow and the weekend to address any problems that pop up. I added some extra comments and questions below.Thanks!-Willem JanWhat may need special attention:The amount of credits:Feedback on this is very much welcomed. Do you think the new application gives the right amount of credit?Stability:Does the application crash? If you pause/stop it, does it resume properly?Progress report:The new application first spends a couple of seconds on determining how many potential triples will be scanned in this workunit. When this scan is complete, it uses this number to estimate how much time remains. This seems to be fairly accurate, since the amount of time per triple doesn't change much inside a workunit, but please let me know if it over/underestimates the required time for you.Total time for a workunit:We have tried to make all workunits roughly the samelength (something in the order of 4 hours, depending a lot on CPU speed of course), and I think it should be more consistent than with the old application. However, there are still some workunits near the edges of the (two dimensional) search area that are longer or shorter than expected, because our time heuristics don't work as well in corner cases. If you run into extreme examples, or think the default length should be shorter or longer, please letme know.Some more technical notes:I looked again at the possibility of a CUDA GPU version, but it doesn't seem like a good fit, since our new algorithm requires fast random memory access, and operates on large integers. GPUs seem to be more suited for localized memory access and floating point data, on the other hand. So sadly I do not think GPU support would increase performance.The code fundamentally uses 64 bit integers since we are looking for ABC triples that don't fit in 32 bit integers. In the new code we included some fast 64 bit arithmetic that is not possible on 32 bit machines, so the speed difference between 64 and 32 bit machines will likely be larger than with the old algorithm.There were some unexplained crashes with the old application on certain linux distributions. If my guess on what caused those is correct, they should notoccur with the new application.
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