Re: [Discuss-gnuradio] ANCI-C vs Gnuradio/C++ speeeed

[Achilleas Anastasopoulos]

I run the following simple test, compiled with
g++ test.cc -o test
and I got the following results.
I see a 4-fold speed reduction using STL.
What am I doing wrong?

Achilleas


---------------------------
$ time ./test 10000 1
real    0m0.121s
user    0m0.120s
sys     0m0.001s

while

$ time ./test 10000 2
real    0m0.462s
user    0m0.459s
sys     0m0.003s

and

$ time ./test 100000 1
real    0m1.185s
user    0m1.184s
sys     0m0.001s

while

$ time ./test 100000 2
real    0m4.597s
user    0m4.595s
sys     0m0.002s
--------------------------


test.cc=================================
#include<vector>

int main(int ac,char **av) {

const int M = 1000;
std::vector<int> y(M);
int *x;
x=(int*)malloc(M*sizeof(int));

int N=atoi(av[1]);

if(atoi(av[2])==1) {
        for (int i=0;i<N;i++)
                for(int j=0;j<M;j++)
                        x[j]=i/(j+1);
} else if(atoi(av[2])==2) {
        for (int i=0;i<N;i++)
                for(int j=0;j<M;j++)
                        y[j]=i/(j+1);
}

}
==================================