compiler settings in AdaGIDE
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From: Ada novice on 24 Jul 2010 08:36 On Jul 24, 2:03 pm, Robert A Duff <bobd...(a)shell01.TheWorld.com> wrote: > > No. I meant -gnatp, not -gnatn. Sorry! > > - Bob Thanks for the clarifications. So I have the options -O3 -gnatn -funroll-loops -gnatf -gnato -fpeel-loops -ftracer - funswitch-loops -fweb -frename-registers -mfpmath=sse -msse3 to play with.
From: Ada novice on 25 Jul 2010 09:29 Many thanks for all these precious information. The settings -gnatnp -O2 -march=native -ffast-math -funroll-loops was only 1 s faster (1537 s) as compared to using -gnatVa -O3 -gnatn -funroll-loops -gnatf -gnato which took 1538 s. I have two questions: 1. I see that you use -gnatnp. Is this safe to do so i.e. to suppress all checks? 2. In the specification -march="machine architecture here", you use native for the machine architecture. Does this apply to Intel processors as well? And thank you very much for making accessible the programs on your website. This is indeed very generous on your part. I find some very useful codes there. YC
From: Jeffrey R. Carter on 25 Jul 2010 15:30 On 07/25/2010 06:29 AM, Ada novice wrote: > > 1. I see that you use -gnatnp. Is this safe to do so i.e. to suppress > all checks? No, but it is a little faster. You asked about maximizing speed, not about safety. Of course, none of this is going to make a significant difference, as you found out yourself. Significant speed changes come about from improved algorithms. The correct approach is to implement correctly, clearly, and safely, then measure against your timing requirements (which are unspecified), and only make changes if the result fails to meet the timing requirements. -- Jeff Carter "I soiled my armor, I was so scared." Monty Python & the Holy Grail 71
From: jonathan on 25 Jul 2010 18:57 On Jul 25, 2:29 pm, Ada novice <po...(a)gmx.us> wrote: > Many thanks for all these precious information. The settings > > -gnatnp -O2 -march=native -ffast-math -funroll-loops > > was only 1 s faster (1537 s) as compared to using > > -gnatVa -O3 -gnatn -funroll-loops -gnatf -gnato Interesting result. I repeated the 100 calls to COMPLEX_EIGENVALUES.Eigen ( P, W, V, FAIL) test on a 121 x 121 sized matrix. I still get the same big decrease in running time from the -ffast-math switch. Generic_Complex_Eigenvalues seems sensitive to -ffast-math, but I've never seen any other program care much about it. > 1. I see that you use -gnatnp. Is this safe to do so i.e. to suppress > all checks? If I remove the -gnatp then running time goes from 3.61 to 6.1 sec. If I remove the -gnatnp then running time goes from 3.61 to 6.7 sec. (I suspect that you know that -gnatnp is really -gnatn -gnatp). On a high percentage of ordinary problems (usually data analysis) I would not care at all about the increased running time, and I would not remove the checks. There is another class of program I write and these run for days or weeks. These I never stop optimizing and testing, and all checks are removed! > 2. In the specification -march="machine architecture here", you use > native for the machine architecture. Does this apply to Intel > processors as well? I just checked the gcc man pages and found nothing at all about -march=native. It helps a little on all the machines I've used and occasionally in the past it has helped enormously. Just now I removed -march=native from the Generic_Complex_Eigenvalues test and running time went from 3.61 sec to 3.58 sec. When I remove it from the Jacobi benchmark, the program slows down slightly. So the switch seems to do something on my intel machine, but all I can say now is that the difference is very small and unpredictable. J.
From: jonathan on 25 Jul 2010 19:40
On Jul 25, 2:29 pm, Ada novice <po...(a)gmx.us> wrote: > 1. I see that you use -gnatnp. Is this safe to do so i.e. to suppress > all checks? I could not resist testing the -gnatp switch on my other benchmark, the Jacobi eigendecomposition. So I removed -gnatp and added -gnato, and running time went from 2.04 sec to 2.35 sec. Not bad at all! J. |