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From: ahmadkhorrami <ahmadkhorrami@ut.ac.ir>
To: Jiri Olsa <jolsa@redhat.com>
Cc: Milian Wolff <milian.wolff@kdab.com>,
	Steven Rostedt <rostedt@goodmis.org>,
	Arnaldo Carvalho de Melo <acme@redhat.com>,
	Linux-trace Users <linux-trace-users@vger.kernel.org>,
	Peter Zijlstra <peterz@infradead.org>,
	linux-trace-users-owner@vger.kernel.org,
	Jin Yao <yao.jin@linux.intel.com>,
	Namhyung Kim <namhyung@kernel.org>,
	Andi Kleen <ak@linux.intel.com>
Subject: Re: Wrong Perf Backtraces
Date: Mon, 30 Mar 2020 23:35:08 +0430
Message-ID: <8cb4f94b11fbac6ca3a44b924b6ee7b3@ut.ac.ir> (raw)
In-Reply-To: <e51e7fc0bed5e79f5e7774fcd5389c3d@ut.ac.ir>

Hi,
Sorry, I did not pay attention to the fact that we need debug info to be 
able to decode the callchain. So, without complete debug info the 
backtrace (either the symbols or the addresses) is bogus. But you say 
that the backtrace portions containing binaries with full debug info are 
OK. Am I right? Please confirm if this is the case.
If so, these portions may be enough for my current usecase.
Regards.

On 2020-03-30 18:19, ahmadkhorrami wrote:

> Hi,
> thanks, but I still do not understand the cause of the problem. It 
> seems that it is purely a software bug and the callchain addresses seem 
> wrong,by themselves. Am I right?
> Regards.
> On 2020-03-30 17:37, Jiri Olsa wrote:
> 
>> On Mon, Mar 30, 2020 at 08:09:53AM +0200, Milian Wolff wrote: On 
>> Sonntag, 29. März 2020 21:20:10 CEST Jiri Olsa wrote: On Sun, Mar 29, 
>> 2020 at 03:50:57PM +0200, Milian Wolff wrote: On Sonntag, 29. März 
>> 2020 14:39:33 CEST ahmadkhorrami wrote: Thanks. I did both of your 
>> changes. Perhaps some outputs are revised.
>> But I still have repeated function calls and the script detects them.
>> Here is one of them when the sampling period is 1000 events: <snip>
>> 
>> Here, we have two consecutive "7f91788120b5
>> gtk_widget_propagate_state+0x195
>> (/usr/lib/x86_64-linux-gnu/libgtk-3.so.0.2200.30) gtkwidget.c:0" 
>> lines,
>> while "gtk_widget_propagate_state+0x195" is not recursive. It should
>> call "gtk_container_forall", which does not occur even after the 
>> second
>> (inner) call.
>> Potentially you are just lacking some debug symbols here for this GTK
>> library. note that "gtkwidget.c:0" is bogus already - the line numbers
>> start with 1, so
> could we just skip those then? pass on all zero lined inlines
> and not add/display them
> I guess so - but quite frankly I'm a bit uneasy to do this without 
> further
> exploration about the actual causes here. Afaik DWARF does not say 
> anything
> about the validity, so in theory there might be some language/compiler 
> that
> encodes valid DWARF locations with line 0?
> 
> Generally, it would be quite interesting to figure out why there is 
> /some/
> DWARF data here such that the code thinks it's able to decode the 
> inline frame
> but then fails and leads to this confusing result?
> right, but it's beyond my DWARF expertise ;-) we'll need
> to wait till one of you guys could take a look on it
> 
> thanks,
> jirka

  reply index

Thread overview: 67+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
     [not found] <157597d74ff17f781d9de7e7e3defd13@ut.ac.ir>
2020-03-22 20:24 ` ahmadkhorrami
2020-03-23  0:34   ` Steven Rostedt
     [not found]     ` <21b3df4080709f193d62b159887e2a83@ut.ac.ir>
2020-03-23  8:49       ` Jiri Olsa
2020-03-23 10:03         ` ahmadkhorrami
2020-03-25 15:18           ` ahmadkhorrami
2020-03-25 15:46             ` Jiri Olsa
2020-03-25 18:54               ` ahmadkhorrami
2020-03-25 18:58               ` Arnaldo Carvalho de Melo
2020-03-25 19:10                 ` ahmadkhorrami
2020-03-25 19:28                   ` Arnaldo Carvalho de Melo
2020-03-25 20:01                     ` ahmadkhorrami
2020-03-25 20:39                       ` Jiri Olsa
2020-03-25 21:02                         ` Jiri Olsa
2020-03-25 21:09                           ` Steven Rostedt
2020-03-25 21:37                             ` ahmadkhorrami
2020-03-25 21:46                               ` Jiri Olsa
2020-03-25 22:21                                 ` ahmadkhorrami
2020-03-25 23:09                                   ` ahmadkhorrami
2020-03-26  9:59                                     ` Jiri Olsa
2020-03-26 13:20                                       ` ahmadkhorrami
2020-03-26 15:39                                         ` Jiri Olsa
2020-03-26 18:19                                           ` ahmadkhorrami
2020-03-26 18:21                                             ` ahmadkhorrami
2020-03-27  9:20                                             ` Jiri Olsa
2020-03-27 10:59                                               ` ahmadkhorrami
2020-03-27 11:04                                                 ` ahmadkhorrami
2020-03-27 12:10                                                   ` Milian Wolff
2020-03-27 12:58                                                     ` ahmadkhorrami
2020-03-27 13:25                                                       ` Milian Wolff
2020-03-27 13:33                                                         ` ahmadkhorrami
2020-03-27 18:43                                                   ` ahmadkhorrami
2020-03-27 22:37                                                     ` Jiri Olsa
2020-03-27 23:12                                                       ` ahmadkhorrami
2020-03-28 23:34                                                         ` Jiri Olsa
2020-03-29  0:43                                                           ` ahmadkhorrami
2020-03-29  1:16                                                             ` ahmadkhorrami
2020-03-29 11:19                                                               ` Jiri Olsa
2020-03-29 11:52                                                                 ` ahmadkhorrami
2020-03-29 12:08                                                                   ` Jiri Olsa
2020-03-29 12:39                                                                     ` ahmadkhorrami
2020-03-29 13:50                                                                       ` Milian Wolff
2020-03-29 14:23                                                                         ` ahmadkhorrami
2020-03-29 19:20                                                                         ` Jiri Olsa
2020-03-30  6:09                                                                           ` Milian Wolff
2020-03-30 13:07                                                                             ` Jiri Olsa
2020-03-30 13:49                                                                               ` ahmadkhorrami
2020-03-30 19:05                                                                                 ` ahmadkhorrami [this message]
2020-03-30 21:05                                                                                   ` debuginfod-based dwarf downloading, was " Frank Ch. Eigler
2020-03-31  9:26                                                                                     ` Jiri Olsa
2020-03-31 14:00                                                                                       ` Frank Ch. Eigler
2020-03-31  4:43                                                                                   ` ahmadkhorrami
2020-03-31  9:30                                                                                     ` Jiri Olsa
2020-03-31 11:53                                                                                       ` ahmadkhorrami
2020-03-31 12:43                                                                                   ` ahmadkhorrami
2020-03-31 13:20                                                                                     ` Jiri Olsa
2020-03-31 13:39                                                                                       ` ahmadkhorrami
2020-03-31 14:44                                                                                         ` Milian Wolff
2020-03-31 15:02                                                                                           ` ahmadkhorrami
2020-03-31 15:05                                                                                             ` ahmadkhorrami
2020-03-31 15:29                                                                                             ` Milian Wolff
2020-03-31 16:10                                                                                               ` Arnaldo Carvalho de Melo
2020-03-31 19:20                                                                                                 ` ahmadkhorrami
2020-03-31 19:17                                                                                               ` ahmadkhorrami
2020-03-31 20:57                                                                                               ` ahmadkhorrami
2020-04-04  1:01                                                                                                 ` ahmadkhorrami
2020-04-11 16:42                                                                                                   ` ahmadkhorrami
2020-04-11 21:04                                                                                                     ` ahmadkhorrami

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