> On Thu, Mar 23, 2017 at 11:25 AM, <kan.li...@intel.com> wrote: > > From: Kan Liang <kan.li...@intel.com> > > > > Currently, there is no way to measure the time cost in System > > management mode (SMM) by perf. > > > > Intel perfmon supports FREEZE_WHILE_SMM bit in IA32_DEBUGCTL. Once > it > > sets, the PMU core counters will freeze on SMI handler. But it will > > not have an effect on free running counters. E.g. APERF counter. > > The cost of SMI can be measured by (aperf - cycles). > > > > A new sysfs entry /sys/device/cpu/freeze_on_smi is introduced to set > > FREEZE_WHILE_SMM bit in IA32_DEBUGCTL. > > > > A new --smi-cost mode in perf stat is implemented to measure the SMI > > cost by calculating cycles and aperf results. In practice, the > > percentages of SMI cycles should be more useful than absolute value. > > So the output will be the percentage of SMI cycles and SMI#. > > > You are talking about the percentage of what cycles? > Wallclock, unhalted_ref_cycles, unhalted_core_cycles?
Unhalted core cycles. Thanks, Kan
