[data from a 233MHz Pentium MMX]

PERFCTR INIT: vendor 0, family 5, model 4, stepping 3, clock 233224 kHz
PERFCTR INIT: NITER == 64
PERFCTR INIT: loop overhead is 55 cycles
PERFCTR INIT: rdtsc cost is 9.7 cycles (676 total)
PERFCTR INIT: rdpmc cost is 15.1 cycles (1026 total)
PERFCTR INIT: rdmsr (counter) cost is 28.2 cycles (1860 total)
PERFCTR INIT: rdmsr (evntsel) cost is 23.8 cycles (1583 total)
PERFCTR INIT: wrmsr (counter) cost is 36.2 cycles (2373 total)
PERFCTR INIT: wrmsr (evntsel) cost is 36.9 cycles (2421 total)
PERFCTR INIT: read %cr4 cost is 4.0 cycles (312 total)
PERFCTR INIT: write %cr4 cost is 17.3 cycles (1165 total)
perfctr: driver 2.0-pre5, cpu type Intel Pentium MMX at 233224 kHz