Re: [PATCH 1/1] Revert "perf report: Append inlines to non-DWARF callchains"

[Artem Savkov]

On Mon, Aug 07, 2023 at 10:34:44AM -0300, Arnaldo Carvalho de Melo wrote:
> Em Mon, Aug 07, 2023 at 01:00:08PM +0200, Artem Savkov escreveu:
> > On Wed, Aug 02, 2023 at 09:43:40AM +0200, Artem Savkov wrote:
> > > Hi Arnaldo,
> > > 
> > > On Tue, Aug 01, 2023 at 06:42:47PM -0300, Arnaldo Carvalho de Melo wrote:
> > > > Hi Artem,
> > > > 
> > > > 	Can you please double check this? I reproduced with:
> > > > 
> > > > git checkout 46d21ec067490ab9cdcc89b9de5aae28786a8b8e
> > > > build it
> > > > perf record -a -g sleep 5s
> > > > perf report
> > > > 
> > > > 	Do you get the same slowness and then reverting it, i.e. just
> > > > going to HEAD~ and rebuilding getting a fast 'perf report' startup, i.e.
> > > > without the inlines in the callchains?
> > > 
> > > With a simple test like this I definitely get a slowdown, but not sure
> > > if it can be called excessive.
> > > 
> > > Below are the times I got by running 'time perf report' and hitting 'q'
> > > during load so that it quits as soon as it is loads up. Tested on a
> > > freshly updated fedora 38.
> > 
> > My bad, I had wrong debuginfo installed for the kernel I tested. I can
> > reproduce it with the correct one. Looks like vmlinux is just too much
> > for addr2line. Maybe we can skip it but leave other inlines in, like so:
> 
> That is a possibilit, and probably we could make it cheaper by looking
> at the cpumode, avoiding calling addr2line when we didn't makage to
> resolve the symbol, etc.
> 
> We also may want to have this as an option that has to be explicitely
> enabled, like --resolve-inlines, as this will add overhead no matter if
> we stop calling addr2line and do it more efficiently, etc.

Sounds good, I'll look into it.

> Fact is, we're late in the 6.5 schedule, so the best thing now is to
> just revert the patch and then try again later, ok?

Yes, sure.

> - Arnaldo
>  
> > diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c
> > index 11de3ca8d4fa7..fef309cd401f7 100644
> > --- a/tools/perf/util/machine.c
> > +++ b/tools/perf/util/machine.c
> > @@ -2388,7 +2388,9 @@ static int add_callchain_ip(struct thread *thread,
> >  	ms.map = map__get(al.map);
> >  	ms.sym = al.sym;
> >  
> > -	if (!branch && append_inlines(cursor, &ms, ip) == 0)
> > +	if (!branch && ms.map && ms.map->dso &&
> > +	    strcmp(ms.map->dso->short_name, "[kernel.vmlinux]") &&
> > +	    append_inlines(cursor, &ms, ip) == 0)
> >  		goto out;
> >  
> >  	srcline = callchain_srcline(&ms, al.addr);
> > 
> > > > - Arnaldo
> > > > 
> > > > ----
> > > > 
> > > > This reverts commit 46d21ec067490ab9cdcc89b9de5aae28786a8b8e.
> > > > 
> > > > The tests were made with a specific workload, further tests on a
> > > > recently updated fedora 38 system with a system wide perf.data file
> > > > shows 'perf report' taking excessive time, so lets revert this until a
> > > > full investigation and improvement on the addr2line support code is
> > > > made.
> > > > 
> > > > Cc: Andrii Nakryiko <andrii.nakryiko@xxxxxxxxx>
> > > > Cc: Artem Savkov <asavkov@xxxxxxxxxx>
> > > > Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
> > > > Cc: Adrian Hunter <adrian.hunter@xxxxxxxxx>
> > > > Cc: Alexander Shishkin <alexander.shishkin@xxxxxxxxxxxxxxx>
> > > > Cc: Ian Rogers <irogers@xxxxxxxxxx>
> > > > Cc: Ingo Molnar <mingo@xxxxxxxxxx>
> > > > Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
> > > > Cc: Mark Rutland <mark.rutland@xxxxxxx>
> > > > Cc: Masami Hiramatsu <mhiramat@xxxxxxxxxx>
> > > > Cc: Milian Wolff <milian.wolff@xxxxxxxx>
> > > > Cc: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
> > > > Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
> > > > ---
> > > >  tools/perf/util/machine.c | 5 -----
> > > >  1 file changed, 5 deletions(-)
> > > > 
> > > > diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c
> > > > index 4e62843d51b7dbf9..f4cb41ee23cdbcfc 100644
> > > > --- a/tools/perf/util/machine.c
> > > > +++ b/tools/perf/util/machine.c
> > > > @@ -45,7 +45,6 @@
> > > >  
> > > >  static void __machine__remove_thread(struct machine *machine, struct thread_rb_node *nd,
> > > >  				     struct thread *th, bool lock);
> > > > -static int append_inlines(struct callchain_cursor *cursor, struct map_symbol *ms, u64 ip);
> > > >  
> > > >  static struct dso *machine__kernel_dso(struct machine *machine)
> > > >  {
> > > > @@ -2385,10 +2384,6 @@ static int add_callchain_ip(struct thread *thread,
> > > >  	ms.maps = maps__get(al.maps);
> > > >  	ms.map = map__get(al.map);
> > > >  	ms.sym = al.sym;
> > > > -
> > > > -	if (!branch && append_inlines(cursor, &ms, ip) == 0)
> > > > -		goto out;
> > > > -
> > > >  	srcline = callchain_srcline(&ms, al.addr);
> > > >  	err = callchain_cursor_append(cursor, ip, &ms,
> > > >  				      branch, flags, nr_loop_iter,
> > > > -- 
> > > > 2.41.0
> > > > 
> > > 
> > > -- 
> > >  Artem
> > 
> > -- 
> >  Artem
> > 
> 
> -- 
> 
> - Arnaldo
> 

-- 
 Artem