Re: Wrong Perf Backtraces

From: Jiri Olsa <jolsa@redhat.com>
To: ahmadkhorrami <ahmadkhorrami@ut.ac.ir>
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 10:20:45 +0100
Message-ID: <20200327092045.GH1947699@krava> (raw)
In-Reply-To: <bf654a5cfe5a2a4188a286f1f5868e17@ut.ac.ir>

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
> 