[data from a 1.8 GHz Athlon]

PERFCTR INIT: vendor 2, family 6, model 10, stepping 0, clock 1837590 kHz
PERFCTR INIT: NITER == 64
PERFCTR INIT: loop overhead is 109 cycles
PERFCTR INIT: rdtsc cost is 15.9 cycles (1130 total)
PERFCTR INIT: rdpmc cost is 14.2 cycles (1023 total)
PERFCTR INIT: rdmsr (counter) cost is 51.4 cycles (3399 total)
PERFCTR INIT: rdmsr (evntsel) cost is 52.5 cycles (3474 total)
PERFCTR INIT: wrmsr (counter) cost is 80.7 cycles (5280 total)
PERFCTR INIT: wrmsr (evntsel) cost is 231.2 cycles (14908 total)
PERFCTR INIT: read cr4 cost is 1.7 cycles (220 total)
PERFCTR INIT: write cr4 cost is 62.4 cycles (4105 total)
PERFCTR INIT: write LVTPC cost is 4.4 cycles (395 total)
perfctr: driver 2.7.3, cpu type AMD K7/K8 at 1837590 kHz