/* https://cirosantilli.com/linux-kernel-module-cheat#profiling-userland-programs */ #include #include #include uint64_t __attribute__ ((noinline)) common(uint64_t n, uint64_t seed) { for (uint64_t i = 0; i < n; ++i) { seed = (seed * seed) - (3 * seed) + 1; } return seed; } uint64_t __attribute__ ((noinline)) fast(uint64_t n, uint64_t seed) { uint64_t max = (n / 10) + 1; for (uint64_t i = 0; i < max; ++i) { seed = common(n, (seed * seed) - (3 * seed) + 1); } return seed; } uint64_t __attribute__ ((noinline)) maybe_slow(uint64_t n, uint64_t seed, int is_slow) { uint64_t max = n; if (is_slow) { max *= 10; } for (uint64_t i = 0; i < max; ++i) { seed = common(n, (seed * seed) - (3 * seed) + 1); } return seed; } int main(int argc, char **argv) { uint64_t n, seed; if (argc > 1) { n = strtoll(argv[1], NULL, 0); } else { n = 1; } if (argc > 2) { seed = strtoll(argv[2], NULL, 0); } else { seed = 0; } seed += maybe_slow(n, seed, 0); seed += fast(n, seed); seed += maybe_slow(n, seed, 1); seed += fast(n, seed); seed += maybe_slow(n, seed, 0); seed += fast(n, seed); printf("%" PRIX64 "\n", seed); return EXIT_SUCCESS; }