Re: Wrong Perf Backtraces

From: ahmadkhorrami <ahmadkhorrami@ut.ac.ir>
To: Jiri Olsa <jolsa@redhat.com>
Cc: 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>,
	Milian Wolff <milian.wolff@kdab.com>,
	Namhyung Kim <namhyung@kernel.org>,
	Changbin Du <changbin.du@intel.com>,
	Andi Kleen <ak@linux.intel.com>
Subject: Re: Wrong Perf Backtraces
Date: Fri, 27 Mar 2020 23:13:27 +0430	[thread overview]
Message-ID: <fd99185b401a451fdbf96439eadcb101@ut.ac.ir> (raw)
In-Reply-To: <decdc878b1bf207c68f1bc9e21178486@ut.ac.ir>

Hi,
I revised the code. Hopefully, it works. Could you check it with your 
own outputs? It is valuable for me to know if your output contains wrong 
backtraces or not. Here is the link:
https://gofile.io/?c=rz2kGc
Regards.

On 2020-03-27 15:34, ahmadkhorrami wrote:

> I do the following:
> If this line is in the perf script backtrace:
> 7f21ffe256db g_main_context_iteration+0x2b 
> (/usr/lib/x86_64-linux-gnu/libglib-2.0.so.0.5600.4)
> I run the following command:
> gdb -batch -ex 'file /usr/lib/x86_64-linux-gnu/libglib-2.0.so.0.5600.4' 
> -ex 'disass g_main_context_iteration'.
> 
> Regards.
> 
> On 2020-03-27 15:29, ahmadkhorrami wrote:
> 
>> Hi,
>> Thanks! Could you tell me what should be changed in order to make the 
>> code runnable on your system, if it is possible?
>> Regards.
>> 
>> On 2020-03-27 13:50, Jiri Olsa wrote:
>> 
>> On Thu, Mar 26, 2020 at 10:49:12PM +0430, ahmadkhorrami wrote:
>> 
>> Hi,
>> Here is the link for the python script:
>> https://gofile.io/?c=1ZSLwe
>> It is written in python-3 and takes the perf script output as input.
>> It looks for consecutive repeated backtrace lines and checks if the 
>> function
>> in these lines calls itself at the offset in the line (i.e., checks if
>> recursion is possible). If not possible it reports an error. Could you 
>> check
>> to see if any error is detected in your outputs, please?
>> I'm getting tons of following output:
>> 
>> /usr/lib/x86_64-linux-gnu/libgtk-3.so.0.2200.30: No such file or 
>> directory.
>> No symbol table is loaded.  Use the "file" command.
>> 7ffff71b9bc1 gtk_css_node_invalidate_timestamp+0x31 
>> (/usr/lib/x86_64-linux-gnu/libgtk-3.so.0.2200.30)
>> 
>> I assume it's because I have all the dso binaries stored
>> under .biuldid path, while you check the output name
>> 
>> jirka
>> 
>> Regards.
>> On 2020-03-26 20:09, Jiri Olsa wrote:
>> 
>> On Thu, Mar 26, 2020 at 05:50:27PM +0430, ahmadkhorrami wrote:
>> 
>> Hi,
>> First of all, many thanks for your time. Did you say that the first
>> file has
>> problems?
>> 
>> The first file (http://gofile.io/?c=qk6oXv) has repeated gmallocn()s
>> while
>> the second (https://gofile.io/?c=oGxgSM) also has problems with
>> unmatched
>> (not necessarily repeated) function calls. I am not sure if the
>> kernel for
>> the second one is 5.4.7 or the generic Ubuntu kernel. But the first
>> one is
>> certainly 5.4.7. Just to be clear, there were many instances of these
>> unmatched <caller, callees>.
>> I can se all the files, but I just can't see the issue yet
>> but it's probably because of issues with perf archive..
>> 
>> let's see if somebody else can chime in
>> 
>> I have a simple python script that checks for this situation. It
>> disassembles functions using GDB and checks the (directly called)
>> target of
>> each caller. I will put some comments in the script and upload it.
>> Could you
>> check to see if the python script detects any mismatches in your
>> backtraces?
>> It takes the perf script output file as input. I will upload the
>> script in
>> an hour.
>> ok
>> 
>> jirka