is D so slow?
Unknown W. Brackets
unknown at simplemachines.org
Sat Jun 14 12:12:56 PDT 2008
This is a frequently asked question.
What compilers are you comparing? They have different optimization
backends. It could be that the C compiler or compiler flags you are
using simply perform better than the comparable D compiler and flags.
-[Unknown]
baleog wrote:
> Hello
> I wrote 2 almost identical test programs(matrix multiplication). One on C and another on D. And D prorgram was 15 times slower!
> Was it my mistake or not?
> Thank you
>
> p.s. code:
> void test (int n) {
> float[] xs = new float[n*n];
> float[] ys = new float[n*n];
> for(int i = n-1; i>=0; --i) {
> xs[i] = 1.0;
> }
> for(int i = n-1; i>=0; --i) {
> ys[i] = 2.0;
> }
> float[] zs = new float[n*n];
> for (int i=0; i<n; ++i) {
> for (int j=0; j<n; ++j) {
> float s = 0.0;
> for (int k=0; k<n; ++k) {
> s = s + (xs[k + (i*n)] * ys[j + (k*n)]);
> }
> zs[j+ (i*n)] = s;
> }
> }
> delete xs;
> delete ys;
> delete zs;
> }
>
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