On Sat, Jul 17, 2010 at 2:03 PM, Dr. David Kirkby <david.kir...@onetel.net> wrote: > On 07/17/10 12:32 PM, William Stein wrote: >> >> On Sat, Jul 17, 2010 at 1:16 PM, Robert Miller<rlmills...@gmail.com> >> wrote: >>> >>> With the rest of the packages, we just do >>> >>> export MAKE="make -j6" >>> >>> to enable parallel building. Why don't we just use this in atlas as >>> well? Why do we need to make a special case? >> >> I think the OP was suggesting building ATLAS so that when it is later >> run it can use multiple cores. >> The above MAKE option merely impacts build time, which is an orthogonal >> problem. >> >> I'm -1 to adding too many environment variables that impact the built >> Sage, because it makes testing sage much, much more difficult, since >> it leads to a combinatorial explosion in the number of different sage >> versions we should test. >> >> -- William >> > > So what do you suggest with ATLAS? > > * Always build with no threading, as is done now?
No. > * Always build so that ATLAS choses the number of threads automatically? Yes. However, with SAGE_FAT_BINARY set, i.e., when making a binary for distribution, maybe then we have to build without threading support. -- William > That might be an issue on systems like t2, where that would be 128, or even > on some of your machines with 24 cores. > > My concerns are > > 1) Building ATLAS with no support for threads will be slow. > 2) Building ATLAS with multiple threads is likely to be more buggy, as > experience tells me that its very hard to create code that works > multi-threaded on lots of platforms. > > I think the present situation (building without threads) is a pretty damm > poor choice, but I'm not convinced the other choices of always building with > threads would be as reliable. In general, and this is no reflection on ATLAS > in particular, writing parallel code is a lot harder than serial code, and > the bugs are hard to trace. > > Dave > > -- > To post to this group, send an email to sage-devel@googlegroups.com > To unsubscribe from this group, send an email to > sage-devel+unsubscr...@googlegroups.com > For more options, visit this group at > http://groups.google.com/group/sage-devel > URL: http://www.sagemath.org > -- William Stein Professor of Mathematics University of Washington http://wstein.org -- To post to this group, send an email to sage-devel@googlegroups.com To unsubscribe from this group, send an email to sage-devel+unsubscr...@googlegroups.com For more options, visit this group at http://groups.google.com/group/sage-devel URL: http://www.sagemath.org
