[data from a 2.2GHz Athlon64-FX (or possibly an Opteron)]

PERFCTR INIT: vendor 2, family 15, model 5, stepping 8, clock 2190647 kHz
PERFCTR INIT: NITER == 64
PERFCTR INIT: loop overhead is 366 cycles
PERFCTR INIT: rdtsc cost is 4.0 cycles (624 total)
PERFCTR INIT: rdpmc cost is 5.6 cycles (729 total)
PERFCTR INIT: rdmsr (counter) cost is 46.5 cycles (3342 total)
PERFCTR INIT: rdmsr (evntsel) cost is 52.3 cycles (3716 total)
PERFCTR INIT: wrmsr (counter) cost is 68.8 cycles (4774 total)
PERFCTR INIT: wrmsr (evntsel) cost is 324.5 cycles (21140 total)
PERFCTR INIT: read cr4 cost is 1.5 cycles (462 total)
PERFCTR INIT: write cr4 cost is 62.5 cycles (4370 total)
PERFCTR INIT: write LVTPC cost is 6.6 cycles (792 total)
perfctr: driver 2.7.3, cpu type AMD K7/K8 at 2190647 kHz