[data from a 1.4GHz Pentium-M]

PERFCTR INIT: vendor 0, family 6, model 9, stepping 5, clock 1396587 kHz
PERFCTR INIT: NITER == 64
PERFCTR INIT: loop overhead is 140 cycles
PERFCTR INIT: rdtsc cost is 51.0 cycles (3404 total)
PERFCTR INIT: rdpmc cost is 43.4 cycles (2920 total)
PERFCTR INIT: rdmsr (counter) cost is 95.0 cycles (6221 total)
PERFCTR INIT: rdmsr (evntsel) cost is 80.8 cycles (5314 total)
PERFCTR INIT: wrmsr (counter) cost is 143.3 cycles (9313 total)
PERFCTR INIT: wrmsr (evntsel) cost is 132.0 cycles (8593 total)
PERFCTR INIT: read cr4 cost is 2.5 cycles (302 total)
PERFCTR INIT: write cr4 cost is 49.5 cycles (3311 total)
PERFCTR INIT: write LVTPC cost is 8.3 cycles (674 total)
perfctr: driver 2.7.3, cpu type Intel P6 at 1396587 kHz