In the original version of this benchmark http://www.netlib.org/benchmark/vectord loops of length 1000 are timed without extra repetitions. The shorter loops are repeated so as to process as much data as the longer one, but repeating over the same cached data, Many of these tests run around 100 microseconds on 2.6Ghz coreI7-2, so a timer with microsecond resolution is needed.
I ran some tests this week on linux with various timers and got reports of microsecond resolution with Intel Openmp omp_get_wtime(). I believe it's nearly that good on Windows. On linux, gettimeofday() is expected to work as well.