Index: libcfa/src/bits/defs.hfa
===================================================================
--- libcfa/src/bits/defs.hfa	(revision 1c40091dd8229cabc50b16e4bc98e6bc658b7fac)
+++ libcfa/src/bits/defs.hfa	(revision 1469a8aabaefc9cc2ab5e6284f5782dfe30243f5)
@@ -47,2 +47,8 @@
 #define OPTIONAL_THREAD __attribute__((weak))
 #endif
+
+static inline long long rdtscl(void) {
+    unsigned int lo, hi;
+    __asm__ __volatile__ ("rdtsc" : "=a"(lo), "=d"(hi));
+    return ( (unsigned long long)lo)|( ((unsigned long long)hi)<<32 );
+}