From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755549AbbLGOEb (ORCPT ); Mon, 7 Dec 2015 09:04:31 -0500 Received: from mx2.suse.de ([195.135.220.15]:52431 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751818AbbLGOEa (ORCPT ); Mon, 7 Dec 2015 09:04:30 -0500 Subject: Re: [RFC] The -Og debugging experience To: Jiri Olsa References: <20151202164827.GA21124@krava.brq.redhat.com> <566563E7.9040706@suse.cz> <20151207134542.GB26191@krava.brq.redhat.com> Cc: Jiri Olsa , Arnaldo Carvalho de Melo , lkml , David Ahern , Ingo Molnar , Namhyung Kim , Peter Zijlstra From: =?UTF-8?Q?Martin_Li=c5=a1ka?= Message-ID: <566591EB.5080404@suse.cz> Date: Mon, 7 Dec 2015 15:04:27 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:38.0) Gecko/20100101 Thunderbird/38.3.0 MIME-Version: 1.0 In-Reply-To: <20151207134542.GB26191@krava.brq.redhat.com> Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 12/07/2015 02:45 PM, Jiri Olsa wrote: > On Mon, Dec 07, 2015 at 11:48:07AM +0100, Martin Liška wrote: >> On 12/02/2015 05:48 PM, Jiri Olsa wrote: >>> heya, >>> using the -Og for DEBUG=1 builds gives me many 'optimized out' stuff >>> >>> It was introduced in here: >>> e8b7ea4356fd perf tools: Improve setting of gcc debug option >>> >>> - here's backtrace from segfault I was looking at, current code: >> >> Hi. >> >> Can you please provide a test-case which I can use for testing of the issue? > > just run perf report in gdb and kill it with sigsegv from other terminal > this gives me several instances of right in the backtrace > > jirka > Hi. Unfortunately, running 'perf report' for a medium-size report is very fast a killing the process from other terminal produces: [Current thread is 1 (Thread 0x7ffff7fc5740 (LWP 7429))] (gdb) bt #0 0x00007ffff632d230 in __write_nocancel () from /lib64/libc.so.6 #1 0x00007ffff62c4dff in _IO_new_file_write () from /lib64/libc.so.6 #2 0x00007ffff62c4403 in new_do_write () from /lib64/libc.so.6 #3 0x00007ffff62c5d09 in __GI__IO_do_write () from /lib64/libc.so.6 #4 0x00007ffff62c5417 in __GI__IO_file_xsputn () from /lib64/libc.so.6 #5 0x00007ffff6299cdb in vfprintf () from /lib64/libc.so.6 #6 0x00007ffff62a03f7 in fprintf () from /lib64/libc.so.6 #7 0x00000000004ef12c in hist_entry__fprintf (he=he@entry=0x1c62b30, size=, size@entry=0, hists=hists@entry=0x1813818, bf=bf@entry=0x1d5cd40 " 0.08% cc1plus cc1plus", ' ' , "[.] _Z25number_of_iterations_exitP4loopP8edge_defP15tree_niter_descbb", ' ' ..., bfsz=bfsz@entry=479, fp=fp@entry=0x7ffff65f0640 <_IO_2_1_stdout_>) at ui/stdio/hist.c:427 #8 0x00000000004ef549 in hists__fprintf (hists=hists@entry=0x1813818, show_header=show_header@entry=true, max_rows=max_rows@entry=0, max_cols=max_cols@entry=0, min_pcnt=0, fp=0x7ffff65f0640 <_IO_2_1_stdout_>) at ui/stdio/hist.c:534 #9 0x000000000042d6a3 in perf_evlist__tty_browse_hists (evlist=0x1812c90, rep=rep@entry=0x7fffffffc6e0, help=help@entry=0x515948 "For a higher level overview, try: perf report --sort comm,dso") at builtin-report.c:370 #10 0x000000000042d7d2 in report__browse_hists (rep=rep@entry=0x7fffffffc6e0) at builtin-report.c:455 #11 0x000000000042d992 in __cmd_report (rep=rep@entry=0x7fffffffc6e0) at builtin-report.c:571 #12 0x000000000042ec1f in cmd_report (argc=0, argv=0x7fffffffde00, prefix=) at builtin-report.c:957 #13 0x000000000046c496 in run_builtin (p=p@entry=0x7771a0 , argc=argc@entry=1, argv=argv@entry=0x7fffffffde00) at perf.c:387 #14 0x000000000046c693 in handle_internal_command (argc=1, argv=0x7fffffffde00) at perf.c:448 #15 0x000000000046c6fe in run_argv (argcp=argcp@entry=0x7fffffffdc6c, argv=argv@entry=0x7fffffffdc60) at perf.c:492 #16 0x000000000046c94c in main (argc=1, argv=0x7fffffffde00) at perf.c:609 Which is fine. I've been using GCC 5.2. What version are you using? I've also tried to run './perf test' and terminate the process at random places, but the back trace was OK. I would appreciate if you send me a patch that causes a segfault that is wrongly displayed. Thanks, Martin