Cray Autotasking

[John D. McCalpin]

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 at masig1.ocean.fsu.edu
		   mccalpin at scri1.scri.fsu.edu
		   mccalpin at delocn.udel.edu