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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: Tue, 31 Mar 2020 17:13:00 +0430
Message-ID: <cc4c1410059a672b81d27a1992cb5a9e@ut.ac.ir> (raw)
In-Reply-To: <8cb4f94b11fbac6ca3a44b924b6ee7b3@ut.ac.ir>

Hi,
Please confirm my thought in the previous email, if it is correct.
Regards.
On 2020-03-30 23:35, ahmadkhorrami wrote:

> 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

  parent 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
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 [this message]
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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