commit 5fb61e827a3757d805b3e2e033cd6fa994f079e1
Author: Vitaliy Filippov <vitalif@yourcmc.ru>
Date:   Tue Sep 28 23:03:44 2021 +0300

    clock_gettime test

diff --git a/test_clock.c b/test_clock.c
new file mode 100644
index 0000000..ca7a952
--- /dev/null
+++ b/test_clock.c
@@ -0,0 +1,39 @@
+#include <stdio.h>
+#include <stdint.h>
+#include <time.h>
+#include "x86intrin.h"
+
+void test_clock(const char *name, clockid_t clockid)
+{
+    struct timespec tp, te;
+    clock_gettime(clockid, &te);
+    for (int i = 0; i < 100000000; i++)
+    {
+        clock_gettime(clockid, &tp);
+    }
+    printf("%s: %lu ns\n", name, (tp.tv_sec-te.tv_sec)*10 + (tp.tv_nsec-te.tv_nsec)/100000000);
+}
+
+void test_rdtsc()
+{
+    struct timespec ts, te;
+    clock_gettime(CLOCK_MONOTONIC, &ts);
+    uint64_t s = __rdtsc(), e;
+    for (int i = 0; i < 100000000; i++)
+    {
+        e = __rdtsc();
+    }
+    clock_gettime(CLOCK_MONOTONIC, &te);
+    printf("RDTSC: %lu ns\n", (te.tv_sec-ts.tv_sec)*10 + (te.tv_nsec-ts.tv_nsec)/100000000);
+}
+
+int main(int narg, char **args)
+{
+    test_rdtsc();
+    test_clock("CLOCK_MONOTONIC_RAW", CLOCK_MONOTONIC_RAW);
+    test_clock("CLOCK_MONOTONIC", CLOCK_MONOTONIC);
+    test_clock("CLOCK_MONOTONIC_COARSE", CLOCK_MONOTONIC_COARSE);
+    test_clock("CLOCK_REALTIME", CLOCK_REALTIME);
+    test_clock("CLOCK_REALTIME_COARSE", CLOCK_REALTIME_COARSE);
+    return 0;
+}