On Fri, Jan 26, 2018 at 03:48:30PM +0900, Namhyung Kim wrote:
> On Fri, Jan 19, 2018 at 05:11:03PM +0100, Jiri Olsa wrote:
> > Current perf report is real slow on newer kernels,
> > with following commit:
> > c0f3ea158939 ("stop using '%pK' for /proc/kallsyms pointer values")
> >
> > which prevent pointers in /proc/kallsyms, in case
> > kernel.perf_event_paranoid=2.
> >
> > That makes perf to fail in finding kernel map details,
> > and keep parsing it again for every kernel sample.
> >
> > Adding and setting a new machine::vmlinux_maps_failed
> > flag after first failed parsing attempt and using it
> > to prevent new pointless parsing.
>
> Hmm.. is it because it's called from machine__resolve() right?
>
> /*
> * Have we already created the kernel maps for this machine?
> *
> * This should have happened earlier, when we processed the kernel MMAP
> * events, but for older perf.data files there was no such thing, so do
> * it now.
> */
>
> It seems that it's only to be compatible with ancient versions.
>
> Do we still need it? I guess they are recorded many years ago (with
> the ancient version) so using addresses of current kernel is just
> meaningless. If one still uses the ancient version, [s]he really
> needs to update it.
right, I think we can remove it.. the reason I see is
that we actualy lookup the kernel maps via the map_group
in machine::kmap, which is static.. so always there
if there were no kernel maps events for some reason,
the map group wil be empty and the search will correctly
fail..
I will send it together with some other fixes later this week
thanks,
jirka
