[data from a 3.4 GHz Pentium 4 Xeon (or maybe non-Xeon)]

PERFCTR INIT: vendor 0, family 15, model 3, stepping 4, clock 3393661 kHz
PERFCTR INIT: NITER == 64
PERFCTR INIT: loop overhead is 348 cycles
PERFCTR INIT: rdtsc cost is 96.1 cycles (6503 total)
PERFCTR INIT: rdpmc cost is 223.9 cycles (14679 total)
PERFCTR INIT: rdmsr (counter) cost is 354.0 cycles (23009 total)
PERFCTR INIT: rdmsr (escr) cost is 375.2 cycles (24361 total)
PERFCTR INIT: wrmsr (counter) cost is 990.9 cycles (63767 total)
PERFCTR INIT: wrmsr (escr) cost is 980.0 cycles (63070 total)
PERFCTR INIT: read cr4 cost is 22.7 cycles (1802 total)
PERFCTR INIT: write cr4 cost is 392.2 cycles (25449 total)
PERFCTR INIT: rdpmc (fast) cost is 90.3 cycles (6129 total)
PERFCTR INIT: rdmsr (cccr) cost is 385.1 cycles (24999 total)
PERFCTR INIT: wrmsr (cccr) cost is 938.5 cycles (60418 total)
PERFCTR INIT: write LVTPC cost is 13.2 cycles (1199 total)
perfctr: driver 2.7.3, cpu type Intel P4 at 3393661 kHz