[data from a 1.8GHz Sempron 3100+]

PERFCTR INIT: vendor 2, family 15, model 12, stepping 0, clock 1804035 kHz
PERFCTR INIT: NITER == 64
PERFCTR INIT: loop overhead is 244 cycles
PERFCTR INIT: rdtsc cost is 9.4 cycles (849 total)
PERFCTR INIT: rdpmc cost is 11.4 cycles (979 total)
PERFCTR INIT: rdmsr (counter) cost is 51.1 cycles (3516 total)
PERFCTR INIT: rdmsr (evntsel) cost is 57.0 cycles (3897 total)
PERFCTR INIT: wrmsr (counter) cost is 72.1 cycles (4859 total)
PERFCTR INIT: wrmsr (evntsel) cost is 328.8 cycles (21291 total)
PERFCTR INIT: read cr4 cost is 5.8 cycles (621 total)
PERFCTR INIT: write cr4 cost is 67.0 cycles (4534 total)
PERFCTR INIT: write LVTPC cost is 22.1 cycles (1663 total)
PERFCTR INIT: sync_core cost is 164.0 cycles (10742 total)
perfctr: driver 2.7.17, cpu type AMD K7/K8 at 1804035 kHz