IA32_MSR_MPERF
uint64 mperf = x86_read_msr(IA32_MSR_MPERF);
gCPU[cpu].arch.mperf_prev = x86_read_msr(IA32_MSR_MPERF);
uint64 mperf2 = x86_read_msr(IA32_MSR_MPERF);