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

[Arnaldo Carvalho de Melo <acme@kernel.org>]

Em Tue, Aug 08, 2023 at 03:38:37PM +0200, Jesper Dangaard Brouer escreveu:
> 
> 
> On 07/08/2023 16.03, Artem Savkov wrote:
> > 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.
> > > > 
> 
> I reported this problem to ACME. It is also possible to reproduce
> without hitting 'q' via using this cmdline with --stdio like this:
> 
>  time perf report -v --stdio > /dev/null 2> debug01.stderr
> 
> The file 'debug01.stderr' contained a lot of addr2line output, that
> might help debug the issue further.
> 
> 
> 
> > > > 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.
> > > > > > 
> 
> Reported-by: Jesper Dangaard Brouer <hawk@kernel.org>

Thanks, I did add that locally, will keep it and add your Tested-by,
thanks a lot!

- Arnaldo
 
> > > > > > Cc: Andrii Nakryiko <andrii.nakryiko@gmail.com>
> > > > > > Cc: Artem Savkov <asavkov@redhat.com>
> > > > > > Cc: Namhyung Kim <namhyung@kernel.org>
> > > > > > Cc: Adrian Hunter <adrian.hunter@intel.com>
> > > > > > Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
> > > > > > Cc: Ian Rogers <irogers@google.com>
> > > > > > Cc: Ingo Molnar <mingo@redhat.com>
> > > > > > Cc: Jiri Olsa <jolsa@kernel.org>
> > > > > > Cc: Mark Rutland <mark.rutland@arm.com>
> > > > > > Cc: Masami Hiramatsu <mhiramat@kernel.org>
> > > > > > Cc: Milian Wolff <milian.wolff@kdab.com>
> > > > > > Cc: Peter Zijlstra <peterz@infradead.org>
> > > > > > Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
> > > > > > ---
> > > > > >   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,
> 
> Tested-by: Jesper Dangaard Brouer <hawk@kernel.org>
> 
> --Jesper

-- 

- Arnaldo