On Nov 29, 2008, at 11:47 AM, mabshoff wrote: > On Nov 29, 11:37 am, Robert Bradshaw <[EMAIL PROTECTED]> > wrote: >>> On Nov 29, 2008, at 07:35 , pong wrote: >> >>>> Hi, >> >>>> I wonder if SAGE is optimized for multi-core CUPs (people >>>> told me >>>> that many programs don't). >> >>> This is not an easy question to answer. Sage is built from many >>> components that were not specifically designed with Sage or >>> multiprocessor issues in mind. >> >>> Most programmers and algorithm designers, even today, don't think in >>> terms of a "tight-coupled" multiprocessor implementation. Some do >>> think of loose coupling. The distinction is the amount of >>> information >>> needed to be shared between the "cooperating processes". For >>> example, >>> Michael and a host of others worked hard to get the Sage build to >>> take >>> advantage of multiple processors. This was not easy, because the >>> components come from many sources, and their build process was not >>> designed to take advantage of these systems, but it was feasible >>> because the different components need very little information >>> from the >>> other components (basically, 'make' has to know what the >>> dependencies >>> are, so it can find independent builds to run at the same time). >> >>> The software that makes up Sage is another matter entirely. Code >>> does >>> not automatically work optimally on a multiprocessor system (whether >>> multi-core or multiple single-core chips). That effort takes a >>> lot of >>> work. >> >> One important component of Sage, ATLAS, does take advantage of >> multiple processors, which is directly taken advantage of in all the >> linear algebra (numeric and exact). > > No, it doesn't per default in Sage on non-OSX since we only build a > single threaded ATLAS there. Due to the Accelerate Framework on OSX > large problems that employ BLAS do use multiple cores automatically. > The Accelerate Framework contains code derived from ATLAS for the BLAS > portion, but that code was never given back by Apple.
I stand corrected--most of my experience is on OSX where it is easy to see both cores being utilized. I didn't know this wasn't the case elsewhere (yet). > I have build Sage versions with a multi CPU ATLAS per default, but > that code never made it into upstream. I have been contemplating what > to do and I do have the following BLAS plan: [...] > Thoughts? Sounds good to me, but I have not experience in the area. - Robert --~--~---------~--~----~------------~-------~--~----~ To post to this group, send email to sage-support@googlegroups.com To unsubscribe from this group, send email to [EMAIL PROTECTED] For more options, visit this group at http://groups.google.com/group/sage-support URLs: http://www.sagemath.org -~----------~----~----~----~------~----~------~--~---
