@charris wrote on 2007-04-11

I think this may be an error in the ATLAS libraries. I am running fc5 here with the ATLAS libraries installed from extras repository, However, those rpms are generated from a script borrowed from Debian, so the problems are probably common to both. Anyway, the following c program also generates the error:

#include <atlas/cblas.h>

int main(int argc, char **argv)
{
    static double a[1000*1000];
    static double b[1000*1000];
    static double c[1000*1000];
    double alpha=1, beta=0;

    cblas_dgemm(CblasRowMajor, CblasNoTrans, CblasNoTrans, 1000, 1000, 1000,
            alpha, a, 1000, b, 1000, beta, c, 1000);
    return 1;
}

Compiled with the command line :

gcc -L/usr/lib64/atlas -lcblas test.c

and which, when run, delivers:

$[charris@swamp blasdot]$ ./a.out
Illegal instruction

For Debian, I believe lib64 should be replaced by lib. Anyway, I think this is either a compiler or ATLAS problem that exhibits itself when the arrays get large enough to require blockiing or some such. I compiled with gcc version 4.1.1. The program works fine if 1000 is replaced by 10 everywhere.

@charris wrote on 2007-04-13

I'm closing this ticket. I compiled ATLAS-3.7.30 for my machine and the test program ran successfully, so this is a problem with the distributed ATLAS libraries. I have filed a bug report with Fedora bugzilla. I suggest that someone who runs Debian or Ubuntu also file bug reports.

BTW, apart from the time, ATLAS-3.7.30 was pretty easy to compile. And the optimization time wasn't bad on this machine, either, < 30 minutes. Apart from that, I believe Whaley recommends using version 3.7 instead of 3.6 because the time between official stable releases has become so long.

ATLAS files available at https://sourceforge.net/project/showfiles.php?group_id=23725

Milestone changed to 1.0.3 Release by @charris on 2007-05-14