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

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Date:   Wed, 2 Aug 2023 09:43:35 +0200
From:   Artem Savkov <asavkov@...hat.com>
To:     Arnaldo Carvalho de Melo <acme@...nel.org>
Cc:     Andrii Nakryiko <andrii.nakryiko@...il.com>,
        Namhyung Kim <namhyung@...nel.org>,
        Adrian Hunter <adrian.hunter@...el.com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Ian Rogers <irogers@...gle.com>,
        Ingo Molnar <mingo@...hat.com>, Jiri Olsa <jolsa@...nel.org>,
        Mark Rutland <mark.rutland@....com>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Milian Wolff <milian.wolff@...b.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 1/1] Revert "perf report: Append inlines to non-DWARF
 callchains"

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.

For 'perf record -a -g sleep 60' (Event count (approx.): 774055090):

with inlines:
$ time ./perf report

real    0m1.477s
user    0m1.324s
sys     0m0.147s

without inlines:
$ time ./perf report

real    0m1.349s
user    0m1.232s
sys     0m0.111s

For 'perf record -a -g sleep 5' (Event count (approx.): 90179399):

with inlines:
$ time ./perf report

real    0m0.657s
user    0m0.555s
sys     0m0.099s

without inlines:
$ time ./perf report

real    0m0.559s
user    0m0.498s
sys     0m0.060s


> - 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@...il.com>
> Cc: Artem Savkov <asavkov@...hat.com>
> Cc: Namhyung Kim <namhyung@...nel.org>
> Cc: Adrian Hunter <adrian.hunter@...el.com>
> Cc: Alexander Shishkin <alexander.shishkin@...ux.intel.com>
> Cc: Ian Rogers <irogers@...gle.com>
> Cc: Ingo Molnar <mingo@...hat.com>
> Cc: Jiri Olsa <jolsa@...nel.org>
> Cc: Mark Rutland <mark.rutland@....com>
> Cc: Masami Hiramatsu <mhiramat@...nel.org>
> Cc: Milian Wolff <milian.wolff@...b.com>
> Cc: Peter Zijlstra <peterz@...radead.org>
> Signed-off-by: Arnaldo Carvalho de Melo <acme@...hat.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,
> -- 
> 2.41.0
> 

-- 
 Artem