MINOR: tools: provide an rdtsc() function for time comparisons
This one returns a timestamp, either the one from the CPU or from
gettimeofday() in 64-bit format. The purpose is to be able to compare
timestamps on various entities to make it easier to detect updates.
It can also be used for benchmarking in certain situations during
development.
diff --git a/include/common/standard.h b/include/common/standard.h
index d0d5065..bb63535 100644
--- a/include/common/standard.h
+++ b/include/common/standard.h
@@ -25,6 +25,7 @@
#include <limits.h>
#include <string.h>
#include <time.h>
+#include <sys/time.h>
#include <sys/types.h>
#include <sys/socket.h>
#include <sys/un.h>
@@ -959,4 +960,23 @@
return code & 0x0f;
}
+/* returns a 64-bit a timestamp with the finest resolution available. The
+ * unit is intentionally not specified. It's mostly used to compare dates.
+ */
+#if defined(__i386__) || defined(__x86_64__)
+static inline unsigned long long rdtsc()
+{
+ unsigned int a, d;
+ asm volatile("rdtsc" : "=a" (a), "=d" (d));
+ return a + ((unsigned long long)d << 32);
+}
+#else
+static inline unsigned long long rdtsc()
+{
+ struct timeval tv;
+ gettimeofday(&tv, NULL);
+ return tv.tv_sec * 1000000 + tv.tv_usec;
+}
+#endif
+
#endif /* _COMMON_STANDARD_H */