MSR_KNC_IA32_PERF_GLOBAL_CTRL
rdmsrq(MSR_KNC_IA32_PERF_GLOBAL_CTRL, val);
wrmsrq(MSR_KNC_IA32_PERF_GLOBAL_CTRL, val);
rdmsrq(MSR_KNC_IA32_PERF_GLOBAL_CTRL, val);
wrmsrq(MSR_KNC_IA32_PERF_GLOBAL_CTRL, val);