profiling: start

userland/gcc/profile.c

@@ -0,0 +1,53 @@
+/* https://cirosantilli.com/linux-kernel-module-cheat#profiling-userland-programs */
+
+#include <inttypes.h>
+#include <stdio.h>
+#include <stdlib.h>
+
+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;
+}