Steven Rostedt <rost...@goodmis.org> writes: > On Mon, 24 Jul 2017 13:46:07 +0800 > "Huang\, Ying" <ying.hu...@intel.com> wrote: > >> Hi, Steven, >> >> We are working on parallelizing secondary CPU bootup. So we need to >> measure the bootup time of secondary CPU, that is, measure time spent in >> smp_init() and its callees. But we found that ftrace now doesn't >> support measure time spent in smp_init() because it is called too early >> (before core_initcall()?). So, do you think it is possible to use >> ftrace to measure secondary CPU bootup time? > > One could trace with function tracing that early, but that wont give > you the timings you are looking for. The best it probably could do is > to look at the function timestamps of what is called after smp_init. > That is, trace smp_init() and sched_init_smp() and take the difference. > > Function graph tracing (which is what you are probably looking for) is > much more heavy weight than function tracing. It requires some setup > that isn't ready that early. Although, I'm sure I can work to get it > there, but it's not trivial.
Got it! Thanks a lot! Best Regards, Huang, Ying > -- Steve
