linux-kernel - Re: [PATCH 0/1] perf report: append inlines to non-dwarf callchains

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Date:   Thu, 30 Mar 2023 08:06:20 +0300
From:   Adrian Hunter <adrian.hunter@...el.com>
To:     Arnaldo Carvalho de Melo <acme@...nel.org>,
        Namhyung Kim <namhyung@...nel.org>, asavkov@...hat.com
Cc:     Peter Zijlstra <peterz@...radead.org>,
        Ingo Molnar <mingo@...hat.com>,
        Mark Rutland <mark.rutland@....com>,
        Alexander Shishkin <alexander.shishkin@...ux.intel.com>,
        Jiri Olsa <jolsa@...nel.org>, Ian Rogers <irogers@...gle.com>,
        linux-perf-users@...r.kernel.org, linux-kernel@...r.kernel.org,
        Milian Wolff <milian.wolff@...b.com>,
        Masami Hiramatsu <mhiramat@...nel.org>,
        Andrii Nakryiko <andrii.nakryiko@...il.com>
Subject: Re: [PATCH 0/1] perf report: append inlines to non-dwarf callchains

On 22/03/23 21:44, Arnaldo Carvalho de Melo wrote:
> Em Wed, Mar 22, 2023 at 11:18:49AM -0700, Namhyung Kim escreveu:
>> On Fri, Mar 17, 2023 at 12:41 AM Artem Savkov <asavkov@...hat.com> wrote:
>>>
>>> On Thu, Mar 16, 2023 at 02:26:18PM -0700, Namhyung Kim wrote:
>>>> Hello,
>>>>
>>>> On Thu, Mar 16, 2023 at 6:36 AM Artem Savkov <asavkov@...hat.com> wrote:
>>>>>
>>>>> In an email to Arnaldo Andrii Nakryiko suggested that perf can get
>>>>> information about inlined functions from dwarf when available and then
>>>>> add it to userspace stacktraces even in framepointer or lbr mode.
>>>>> Looking closer at perf it turned out all required bits and pieces are
>>>>> already there and inline information can be easily added to both
>>>>> framepointer and lbr callchains by adding an append_inlines() call to
>>>>> add_callchain_ip().
>>>>
>>>> Looks great!  Have you checked it with perf report -g callee ?
>>>> I'm not sure the ordering of inlined functions is maintained
>>>> properly.  Maybe you can use --no-children too to simplify
>>>> the output.
>>>
>>> Thanks for the suggestion. I actually have another test program with
>>> functions being numbered rather than (creatively) named, so it might be
>>> easier to use it to figure out ordering. Here's the code:
>>
>> Yep, looks good.
>>
>> Acked-by: Namhyung Kim <namhyung@...nel.org>
> 
> So, I'll apply this shorter patch instead, ok?
> 
> - Arnaldo
> 
> diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c
> index 803c9d1803dd26ef..abf6167f28217fe6 100644
> --- a/tools/perf/util/machine.c
> +++ b/tools/perf/util/machine.c
> @@ -44,6 +44,7 @@
>  #include <linux/zalloc.h>
>  
>  static void __machine__remove_thread(struct machine *machine, 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)
>  {
> @@ -2322,6 +2323,10 @@ static int add_callchain_ip(struct thread *thread,
>  	ms.maps = al.maps;
>  	ms.map = al.map;
>  	ms.sym = al.sym;
> +
> +	if (append_inlines(cursor, &ms, ip) == 0)
> +		return 0;
> +
>  	srcline = callchain_srcline(&ms, al.addr);
>  	return callchain_cursor_append(cursor, ip, &ms,
>  				       branch, flags, nr_loop_iter,

This seems to be breaking --branch-history.  I am not sure
append_inlines() makes sense for branches.  Maybe this should be:

	if (!branch && !append_inlines(cursor, &ms, ip))
		return 0;