Date:   Tue, 8 Aug 2023 15:38:37 +0200
From:   Jesper Dangaard Brouer <hawk@...nel.org>
To:     Artem Savkov <asavkov@...hat.com>,
        Arnaldo Carvalho de Melo <acme@...nel.org>
Cc:     Jesper Dangaard Brouer <hawk@...nel.org>,
        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"



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@...nel.org>

>>>>> 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,

Tested-by: Jesper Dangaard Brouer <hawk@...nel.org>

--Jesper

Powered by blists - more mailing lists