hemant@acsu.buffalo.edu (Hemant Dandekar) (04/19/91)
Hi, I am trying to run a program written in Fortran on a Cray-2 running UNICOS 6.1 and CF77.4.0.3 under autotasking. Using the option -Wu"-p" and running my code in time share mode I generate the output which can be used by 'atexpert' a autotasking tool. The 'atexpert' tool predicts the speedup of the code in 'standalone' mode based on the information it is fed. However, I get very poor speedup compared to the predictions when I run my code on a 4 processor Cray-2 at NCSA. Here is a comparison between predicted and actual values. # of CPUS Speedup (atexpert) Speedup(Actual) -------------------------------------------------------------------- 1 1.0 1.00 2 1.9 1.27 3 2.8 1.32 4 3.6 1.33 -------------------------------------------------------------------- Before I run my code I set my MICRO_NICE value to 0 and my NCPUS value (these are shell variables) to 1, 2, 3 or 4. I do not set my MICRO_TIMEOUT variable to a large value as suggested by Dick Steimann, of CCN Cray Systems group. However, I don't think any of my slave CPU's remain idle as the breakup of CPU time for a typical run is as follows: NCPUS = 3 1 CPU 83.31s 2 CPU 45.76s 3 CPU 26.40s out of a total CPU time of 155.47seconds. An obvious way to check things out will be to make another dedicated run with setting the MICRO_TIMEOUT variable to a large values such as 10000. However, I cannot make another run for another week. Meanwhile, I would be curious to know about the experiences of other users on the net with regards to autotasking on the CRAY-2 under UNICOS 6.0+ and their experience with 'atexpert' predictions and actual performance. Thanks, hemant ********* BITNET: V092QGHG@UBVMS.BITNET |Hemant W. Dandekar INTERNET: hemant@eng.buffalo.edu|303, Furnas Hall, SUNY at Buffalo u10978@u2.ncsa.uiuc.edu|Amherst NY 14260 (716)636-2631(work) -- ---------------------------------------------------------------------------- Bitnet: v092qghg@ubvms.bitnet | Hemant W. Dandekar Internet: hemant@asterix.eng.buffalo.edu| 303, Furnas Hall, Chem. Eng. (716)636-2631 | SUNY at Buffalo, Buffalo NY 14260