/*
- * define GMX_USE_RDTSCP to use the serializing rdtscp instruction instead of rdtsc.
+ * define GMX_USE_RDTSCP=1 to use the serializing rdtscp instruction instead of rdtsc.
* This is only supported on newer Intel/AMD hardware, but provides better accuracy.
*/
typedef __int64 tMPI_Cycles_t;
static __inline tMPI_Cycles_t tMPI_Cycles_read(void)
{
-#ifdef GMX_USE_RDTSCP
+#if GMX_USE_RDTSCP
unsigned int ui;
return __rdtscp(&ui);
#else