On Fri, Jul 08, 2016 at 12:08:19PM +0200, Ingo Molnar wrote: > > * Byungchul Park <[email protected]> wrote: > > > On Mon, Jul 04, 2016 at 07:27:54PM +0900, Byungchul Park wrote: > > > I suggested this patch on https://lkml.org/lkml/2016/6/20/22. However, > > > I want to proceed saperately since it's somewhat independent from each > > > other. Frankly speaking, I want this patchset to be accepted at first so > > > that the crossfeature can use this optimized save_stack_trace_norm() > > > which makes crossrelease work smoothly. > > > > What do you think about this way to improve it? > > I like both of your improvements, the speed up is impressive: > > [ 2.327597] save_stack_trace() takes 87114 ns > ... > [ 2.781694] save_stack_trace() takes 20044 ns > ... > [ 3.103264] save_stack_trace takes 3821 (sched_lock) > > Could you please also measure call graph recording (perf record -g), how much > faster does it get with your patches and what are our remaining performance > hot > spots?
I don't think it will impact much perf because print_context_stack_bp() checks ops->address() which return perf_callchain_store() which tells if we crossed the buffer limit. But it's worth checking anyway. Thanks.
