[data from a 3.0 GHz Intel Core 2 Duo E8400]

PERFCTR INIT: vendor 0, family 6, model 23, stepping 6, clock 3005665 kHz
PERFCTR INIT: NITER == 64
PERFCTR INIT: loop overhead is 396 cycles
PERFCTR INIT: rdtsc cost is 31.0 cycles (2385 total)
PERFCTR INIT: rdpmc cost is 53.1 cycles (3798 total)
PERFCTR INIT: rdmsr (counter) cost is 208.4 cycles (13734 total)
PERFCTR INIT: rdmsr (evntsel) cost is 185.3 cycles (12258 total)
PERFCTR INIT: wrmsr (counter) cost is 273.9 cycles (17928 total)
PERFCTR INIT: wrmsr (evntsel) cost is 241.3 cycles (15840 total)
PERFCTR INIT: read cr4 cost is 7.4 cycles (873 total)
PERFCTR INIT: write cr4 cost is 123.1 cycles (8280 total)
PERFCTR INIT: write LVTPC cost is 22.3 cycles (1827 total)
PERFCTR INIT: sync_core cost is 269.8 cycles (17667 total)
PERFCTR INIT: read fixed_ctr0 cost is 52.8 cycles (3780 total)
PERFCTR INIT: wrmsr fixed_ctr_ctrl cost is 278.2 cycles (18207 total)
perfctr: driver 2.6.34, cpu type Intel Core 2 at 3005665 kHz