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Why the parallelization does not work?

xu_jocelyn
Beginner
‎01-05-2008 07:12 PM
536 Views

With IVF Compiler 10.1, A same program performs on IA32 architecture (Intel Pentium D CPU/ Ms Windows XP Home Edition) and Intel 64 architecture (Dual-Core AMD Opteron Processor 2214 / Ms Windows Server 2003 Enterprise x64 Edition SP2) respectively. Both projects are optimized with '/O3 /Og /QaxN /QxN /Qparallel' etc. Few loops in program main are auto-parallelized or vectorized.

Then, I add some '!DEC$ PARALLEL' directives before the appropriate loops, however, no otherinformation of 'auto-parallelized' appears, and the running efficiency does not improved in fact. Why the directive does not work?

Moreover, the dual-core or quad-core processors above seem not work, while the auto-parallelized program runs almost with only single core. Could the auto-parallelization fully use all cores of CPU? Or my settings have any mistakes? What is the best setting about above two systems?

Thanks!

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Steven_L_Intel1
Employee
‎01-06-2008 08:04 AM
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I'd suggest that you make use of the optimization reports to see what the compiler thought of your loops.

By the way, there's no point in saying both /QxN and /QaxN. I suggest /QxW /QaxP.

If you're seriously interested in making use of the multiple cores, I recommend looking at OpenMP rather than auto-parallel.
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