Hi,
I have a very simple Jacobi example. However, if I play around with different vector sizes (loop schedules), I get the error “call to cuStreamSynchronize returned error 700: Launch failed” when taking sizes > 256. That is a problem for 14.2, 14.1, 13.10, 13.9. With 13.6 this code is correctly working.
I assume that is a compiler bug, isn’t it? If so, I can send you the whole example if needed. If not, let me know what I am doing wrong. But actually, changing the loop schedule should not effect the output (as long as I am in a valid thread number range).
BTW: I use a NVIDIA Quadro 6000 (Fermi) and the flags -acc -ta:nvidia,cuda5.0
#pragma acc data copy(A[0:m*n]) create(Anew[0:m*n])
{
while ( err > tol && iter < iter_max ) {
err = 0.0;
#pragma acc parallel loop present(Anew[0:n*m],A[0:n*m]) reduction(max:err) vector_length(257)
for( j = 1; j < n-1; j++) {
for( i = 1; i < m-1; i++ ) {
Anew[j *m+ i] = 0.25 * ( A[j *m+ (i+1)] + A[j *m+ (i-1)]
+ A[(j-1) *m+ i] + A[(j+1) *m+ i]);
err = fmax(err,fabs(Anew[j*m+i]-A[j*m+i]));
}
}
#pragma acc parallel loop present(Anew[0:n*m],A[0:n*m])
for( j = 1; j < n-1; j++) {
for( i = 1; i < m-1; i++ ) {
A[j *m+ i] = Anew[j *m+ i];
}
}
if(iter % 10 == 0) {
printf("%5d, %0.6f\n", iter, err);
}
iter++;
} // end while
}
The code uses dynamically allocated arrays.
Sandra