Moreover, I have implemented a good random function I have found here: http://astronomy.swin.edu.au/~pbourke/other/random/randomlib.c I have compiled it as a dynamic library, in order to simulate the same conditions that glibc's rand() function. I have compiles the test and gives these results: # ./libcliente 10 M de rand() en 46.950 s. (ejemplo.: 186687031) 10 M de fakerand() en 1.060 s. (ejemplo.: 867) Recycling code I have called this external function with the old name "fakerand", but it is a good alternative to standard random generators. Conclusion: The system behaves correctly when invoking another random algorithm dynamically.