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On Mon, 27 Sep 2004 11:00:08 -0500 Linas Vepstas <linas@austin.ibm.com> wrote: > You should test again with optimization turned on. This can make > a *huge* difference in relative performance. Without optimization, > the compiler does literally what the C code says, with an excess use > of register-to-register copies. Thus, and sort of redundant Hi Linas, very good point! What you suggest is longer to say than to do gcc -O3 -march=i686 -lgsl -lgslcblas testran.c -o testran results (ignore the value for a, it doesn't matter) : value for a value for b JOHNSON (secs) TADIKAMALLA (secs) 1.000000 0.500000 0.540000 3.630000 1.000000 0.600000 1.590000 2.880000 1.000000 0.700000 1.550000 2.500000 1.000000 0.800000 1.490000 2.290000 1.000000 0.900000 1.430000 2.170000 1.000000 1.000000 0.510000 0.220000 1.000000 1.100000 1.330000 2.160000 1.000000 1.200000 1.330000 2.180000 1.000000 1.300000 1.330000 2.160000 1.000000 1.400000 1.320000 2.180000 1.000000 1.500000 1.310000 2.180000 1.000000 1.600000 1.320000 2.170000 1.000000 1.700000 1.300000 2.170000 1.000000 1.800000 1.290000 2.180000 1.000000 1.900000 1.290000 2.180000 1.000000 2.000000 1.290000 0.410000 1.000000 2.100000 1.280000 4.370000 1.000000 2.200000 1.270000 4.370000 1.000000 2.300000 1.270000 4.360000 1.000000 2.400000 1.260000 4.370000 1.000000 2.500000 1.260000 4.370000 1.000000 2.600000 1.250000 4.370000 1.000000 2.700000 1.250000 4.380000 1.000000 2.800000 1.250000 4.380000 1.000000 2.900000 1.250000 4.380000 1.000000 3.000000 1.230000 3.920000 1.000000 3.200000 1.230000 4.390000 1.000000 3.400000 1.230000 4.370000 1.000000 3.600000 1.220000 4.370000 1.000000 3.800000 1.210000 4.370000 1.000000 4.000000 1.210000 3.960000 comment: things did not change, JOHNSON is ALWAYS faster. BTW I've tested also on a dual opteron compiling with gcc -O3 -lgsl -lgslcblas testran.c -o testran guess what? same thing: JOHNSON is ALWAYS faster. Any other optimization option to suggest? G. -- Giulio Bottazzi <bottazzi@sssup.it> Laboratory of Economics and Management Sant'Anna School for Advanced Studies, Pisa, Italy Phone: (+39)-050-883365 Fax: (+39)-050-883344 URL: http://www.sssup.it/~bottazzi/
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