[data from a 2.0 GHz Athlon64]

PERFCTR INIT: vendor 2, family 15, model 4, stepping 8, clock 2000139 kHz
PERFCTR INIT: NITER == 64
PERFCTR INIT: loop overhead is 79 cycles
PERFCTR INIT: rdtsc cost is 6.2 cycles (479 total)
PERFCTR INIT: rdpmc cost is 13.3 cycles (936 total)
PERFCTR INIT: rdmsr (counter) cost is 50.9 cycles (3342 total)
PERFCTR INIT: rdmsr (evntsel) cost is 56.6 cycles (3703 total)
PERFCTR INIT: wrmsr (counter) cost is 72.7 cycles (4737 total)
PERFCTR INIT: wrmsr (evntsel) cost is 333.0 cycles (21396 total)
PERFCTR INIT: read cr4 cost is 5.9 cycles (462 total)
PERFCTR INIT: write cr4 cost is 67.1 cycles (4375 total)
perfctr: disabled lapic_nmi_watchdog
perfctr: driver 2.6.2, cpu type AMD K8C at 2000139 kHz
