Path: utzoo!utgpu!jarvis.csri.toronto.edu!mailrus!uwm.edu!uakari.primate.wisc.edu!uflorida!stat!stat.fsu.edu!mccalpin From: mccalpin@masig3.ocean.fsu.edu (John D. McCalpin) Newsgroups: comp.unix.cray,comp.sys.super Subject: Cray Autotasking Message-ID: Date: 27 Nov 89 13:08:06 GMT Sender: news@stat.fsu.edu Distribution: usa Organization: Supercomputer Computations Research Institute Lines: 30 Does anyone know offhand how the Cray autotasking splits loops between processors? Specifically, in the following loop: do 200 iseg=1,8 do 100 i=istart(iseg),istop(iseg) a(i,j(iseg)) = b(i,j(iseg))+two*c(i,j(iseg)) 100 continue 200 continue Does a 4-cpu system do iterations like this cpu # iseg ----- ---- 0 1,2 1 3,4 2 5,6 3 7,8 or like this cpu # iseg ----- ---- 0 1,5 1 2,6 2 3,7 3 4,8 I plan to sort the segments by length to help with load balancing, and need to know which segments go to which cpu so that I can decide exactly how to sort them. -- John D. McCalpin - mccalpin@masig1.ocean.fsu.edu mccalpin@scri1.scri.fsu.edu mccalpin@delocn.udel.edu