[data from a 2.8 GHz Pentium 4 Xeon (Northwood)]

PERFCTR INIT: vendor 0, family 15, model 2, stepping 7, clock 2799309 kHz
PERFCTR INIT: NITER == 64
PERFCTR INIT: loop overhead is 264 cycles
PERFCTR INIT: rdtsc cost is 82.1 cycles (5520 total)
PERFCTR INIT: rdpmc cost is 151.1 cycles (9940 total)
PERFCTR INIT: rdmsr (counter) cost is 255.0 cycles (16584 total)
PERFCTR INIT: rdmsr (escr) cost is 166.2 cycles (10904 total)
PERFCTR INIT: wrmsr (counter) cost is 793.0 cycles (51020 total)
PERFCTR INIT: wrmsr (escr) cost is 872.7 cycles (56120 total)
PERFCTR INIT: read cr4 cost is 5.0 cycles (584 total)
PERFCTR INIT: write cr4 cost is 253.6 cycles (16500 total)
PERFCTR INIT: rdpmc (fast) cost is 61.2 cycles (4184 total)
PERFCTR INIT: rdmsr (cccr) cost is 167.0 cycles (10952 total)
PERFCTR INIT: wrmsr (cccr) cost is 832.8 cycles (53564 total)
perfctr: driver 2.5.5, cpu type Intel Pentium 4 Model 2 at 2799309 kHz