[data from an 800 MHz Athlon]

PERFCTR INIT: vendor 2, family 6, model 4, stepping 2, clock 800450 kHz
PERFCTR INIT: NITER == 64
PERFCTR INIT: loop overhead is 164 cycles
PERFCTR INIT: rdtsc cost is 13.9 cycles (1057 total)
PERFCTR INIT: rdpmc cost is 12.3 cycles (956 total)
PERFCTR INIT: rdmsr (counter) cost is 51.7 cycles (3478 total)
PERFCTR INIT: rdmsr (evntsel) cost is 52.5 cycles (3527 total)
PERFCTR INIT: wrmsr (counter) cost is 82.9 cycles (5472 total)
PERFCTR INIT: wrmsr (evntsel) cost is 231.5 cycles (14983 total)
PERFCTR INIT: read cr4 cost is 2.0 cycles (295 total)
PERFCTR INIT: write cr4 cost is 63.1 cycles (4208 total)
PERFCTR INIT: sync_core cost is 73.0 cycles (4840 total)
perfctr: driver 2.7.5, cpu type AMD K7/K8 at 800450 kHz