Re: [PATCH 2/3] perf callchain: Stop resolving callchains after invalid address

Arnaldo Carvalho de Melo
2015-11-26T16:19:08Z

Em Thu, Nov 26, 2015 at 04:58:57PM +0100, Jiri Olsa escreveu:
> On Thu, Nov 26, 2015 at 08:48:17AM -0700, David Ahern wrote:
> > On 11/26/15 8:00 AM, Namhyung Kim wrote:
> > >Hi David,
> > >
> > >On Thu, Nov 26, 2015 at 06:14:57AM -0700, David Ahern wrote:
> > >>On 11/26/15 12:08 AM, Namhyung Kim wrote:
> > >>>@@ -528,11 +529,16 @@ int main(int argc, const char **argv)
> > >>> {
> > >>> const char *cmd;
> > >>> char sbuf[STRERR_BUFSIZE];
> > >>>+ int min_addr;
> > >>>
> > >>> /* The page_size is placed in util object. */
> > >>> page_size = sysconf(_SC_PAGE_SIZE);
> > >>> cacheline_size = sysconf(_SC_LEVEL1_DCACHE_LINESIZE);
> > >>>
> > >>>+ if (sysctl__read_int("vm/mmap_min_addr", &min_addr) < 0)

Please put this in that symbol_conf kitchen sink :-)

I'm unsure though if there would be a reason for having both the local
min_addr and the one at perf record time, i.e. from perf.data :-\

> > >>This assumes the record and analysis are done on the same system.
> > >
> > >Right. Maybe we can just use minimal size (or page size?) or save and
> > >pass it through somewhere in the feature bit?
> >
> > no preference, but it should work with cross arch analysis as well (e.g.,
> > record on arm/ppc and analysis on x86)
>
> I think we should store it in perf.data in features, but seems
> like a waste to spend one bit just for this number.
>
> I remember commenting on new CPU related FEATURE data, that would contain
> cpu specific data in extensible form like TAG,VALUE,TAG,VALUE..
>
> but I think the design changed or something, because I cannot find it in now ;-)
>
> maybe we could add something like that

Right, isn't that one part of the perf/stat patchkit?

- Arnaldo