[data from a dual quad-core 2.2 GHz Opteron 8354 (Sun X4200) running 2.6.18-53.1.4.el5]

PERFCTR INIT: vendor 2, family 16, model 2, stepping 2, clock 2194172 kHz
PERFCTR INIT: NITER == 64
PERFCTR INIT: loop overhead is 568 cycles
PERFCTR INIT: rdtsc cost is 120.7 cycles (8298 total)
PERFCTR INIT: rdpmc cost is 12.8 cycles (1393 total)
PERFCTR INIT: rdmsr (counter) cost is 104.0 cycles (7226 total)
PERFCTR INIT: rdmsr (evntsel) cost is 120.0 cycles (8250 total)
PERFCTR INIT: wrmsr (counter) cost is 149.6 cycles (10143 total)
PERFCTR INIT: wrmsr (evntsel) cost is 465.8 cycles (30380 total)
PERFCTR INIT: read cr4 cost is 23.2 cycles (2055 total)
PERFCTR INIT: write cr4 cost is 133.5 cycles (9118 total)
PERFCTR INIT: write LVTPC cost is 61.2 cycles (4490 total)
PERFCTR INIT: sync_core cost is 285.2 cycles (18826 total)
perfctr: driver 2.6.31, cpu type AMD K7/K8/Fam10h at 2194172 kHz
