Re: [atlas-devel] Debian package of Atlas Was: Re: change in dynamic build
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From: Clint W. <wh...@cs...> - 2011-12-29 18:24:28
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Sylvestre, >I am not happy to see ATLAS in this condition in Debian or Ubuntu. > >Just to sum up, my two test cases are: >* build a low performances ATLAS which will run anywhere OK, the easiest approach to this is to simply build ATLAS on the oldest machine that you want to support. The oldest chip with x87 support (I don't think it is worth supporting software floating-point) is the PentiumPRO. Have you considered simply using ATLAS installed on a PPRO for this case? PPRO is a good target because it has the smallest L1 of any x86 chip, and so something built on it won't overflow the cache of any x86 machine that I'm aware of. The performance will be *terrible* on modern intel machines, where the AVX performance can be something like 8x or 16x faster than x87, and since we are using only the x87, we won't even have prefetch (so even bus-bound operations like the L1/L2 BLAS will be slower). It will, however, still be faster than the reference BLAS, which is what I understand you guys are aiming for in this build. If you don't have a PPRO, I do. I was planning on dropping architectural default support for the PPRO this cycle (ATLAS would still work, just would require a full search on a very slow machine). However, if it will help the debian folks out, I can resurrect the machine, and even give you access. >* build Debian packages in just one or two commands which will be >optimized for my arch. > >The second test case is working very well. OK, this case is working (other than the reported bugs) for 3.9? >The problem that I have is >with the first one (which what is built by debian toolchains). > >If you want, I can generated the error on a server and give you ssh >access. Trying to fool ATLAS into building the wrong lib on modern architecture is always going to be *much* more difficult (even for me) than building it directly on a lowest-common-denominator machine like the PPRO. Let's figure out if that will work for you first! Thanks, Clint ************************************************************************** ** R. Clint Whaley, PhD ** Assist Prof, UTSA ** www.cs.utsa.edu/~whaley ** ************************************************************************** |