+/* There are two types of clocks that can be used.
+ - TSC based clock
+ - gettimeofday() clock
+
+ Microbenchmarks on Linux 2.6.30 on Core2 Duo 3GHz (functions are inlined):
+ Calls (100000000) to tsc(): 4004035641 cycles or 40 cycles/call
+ Calls (100000000) to gettimeofday(): 9723158352 cycles or 97 cycles/call
+
+ For merging traces with the kernel, a time source compatible with that of
+ the kernel is necessary.
+
+*/
+
+#if 0
+/* WARNING: Make sure to set frequency and scaling functions that will not
+ * result in lttv timestamps (sec.nsec) with seconds greater than 2**32-1.
+ */
+static inline u64 trace_clock_read64(void)
+{
+ uint32_t low;
+ uint32_t high;
+ uint64_t retval;
+ __asm__ volatile ("rdtsc\n" : "=a" (low), "=d" (high));
+
+ retval = high;
+ retval <<= 32;
+ return retval | low;
+}
+#endif
+