On Fri, May 26, 2017 at 12:05:36PM -0700, [email protected] wrote: > From: Kan Liang <[email protected]> > > 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 - unhalted core cycles). > > A new sysfs entry /sys/device/cpu/freeze_on_smi is introduced to set > FREEZE_WHILE_SMM bit in IA32_DEBUGCTL. (kernel patch, which has been merged. > The commit ID is 6089327f5424f227bb6a8cf92363c2617e054453) > > A new --smi-cost mode in perf stat is implemented to measure the SMI cost > by calculating unhalted core cycles and aperf results. > > In practice, the percentages of SMI cycles is very useful for performance > oriented analysis. So the output will be SMI cycles% and SMI#. > For users who wants to get the actual value, they can apply --no-metric-only. > > Here is an example of default output. > > Performance counter stats for 'sudo echo ': > > SMI cycles% SMI# > 0.1% 1 > > 0.010858678 seconds time elapsed
for some reason I can't get single SMI count generated, is there a setup/bench that would provoke that? other than that, the code looks ok thanks, jirka
