[data from an AthlonXP 1800]

PERFCTR INIT: vendor 2, family 6, model 6, stepping 2, clock 1534167 kHz
PERFCTR INIT: NITER == 64
PERFCTR INIT: loop overhead is 147 cycles
PERFCTR INIT: rdtsc cost is 15.6 cycles (1148 total)
PERFCTR INIT: rdpmc cost is 13.5 cycles (1011 total)
PERFCTR INIT: rdmsr (counter) cost is 50.8 cycles (3399 total)
PERFCTR INIT: rdmsr (evntsel) cost is 52.0 cycles (3475 total)
PERFCTR INIT: wrmsr (counter) cost is 79.0 cycles (5203 total)
PERFCTR INIT: wrmsr (evntsel) cost is 230.5 cycles (14905 total)
PERFCTR INIT: read cr4 cost is 1.4 cycles (242 total)
PERFCTR INIT: write cr4 cost is 63.9 cycles (4242 total)
PERFCTR INIT: write LVTPC cost is 3.9 cycles (401 total)
perfctr: driver 2.7.3, cpu type AMD K7/K8 at 1534167 kHz