From mboxrd@z Thu Jan 1 00:00:00 1970 From: Arnaldo Carvalho de Melo Subject: Re: [PATCH] perf report: Support caller callchain order when using DWARF unwinder. Date: Mon, 2 Nov 2015 18:19:44 -0300 Message-ID: <20151102211944.GR2923@kernel.org> References: <1443971797-25548-1-git-send-email-milian.wolff@kdab.com> <20151004203817.GE20515@kernel.org> <20151005110836.GA28364@krava.landal.opennet> <2192570.dg0L2eaEiH@agathebauer> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from mail.kernel.org ([198.145.29.136]:32982 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752296AbbKBVTu (ORCPT ); Mon, 2 Nov 2015 16:19:50 -0500 Content-Disposition: inline In-Reply-To: <2192570.dg0L2eaEiH@agathebauer> Sender: linux-perf-users-owner@vger.kernel.org List-ID: To: Milian Wolff Cc: Jiri Olsa , linux-perf-users@vger.kernel.org, Jiri Olsa , Namhyung Kim , =?iso-8859-1?Q?Fr=E9d=E9ric?= Weisbecker Em Fri, Oct 09, 2015 at 07:29:34PM +0200, Milian Wolff escreveu: > On Montag, 5. Oktober 2015 13:08:36 CEST Jiri Olsa wrote: > > On Sun, Oct 04, 2015 at 05:38:17PM -0300, Arnaldo Carvalho de Melo wrote: > > > Em Sun, Oct 04, 2015 at 05:16:37PM +0200, Milian Wolff escreveu: > > > > We cannot reverse the order of the libunwind stepper. To workaround > > > > this, we store the IPs in a temporary stack buffer and then walk > > > > this buffer in reverse order when callchain_param.order is set to > > > > ORDER_CALLER. > > > > > > > > Signed-off-by: Milian Wolff > > > > > > Jiri, > > > > > > Can you please take a look at this? > > > > > > - Arnaldo > > > > > > > Cc: Arnaldo Carvalho de Melo > > > > --- > > > > > > > > tools/perf/util/unwind-libunwind.c | 21 +++++++++++++++++---- > > > > 1 file changed, 17 insertions(+), 4 deletions(-) > > > > > > > > diff --git a/tools/perf/util/unwind-libunwind.c > > > > b/tools/perf/util/unwind-libunwind.c index 4c00507..bf631f1 100644 > > > > --- a/tools/perf/util/unwind-libunwind.c > > > > +++ b/tools/perf/util/unwind-libunwind.c > > > > @@ -621,11 +621,24 @@ static int get_entries(struct unwind_info *ui, > > > > unwind_entry_cb_t cb,> > > > > > if (ret) > > > > > > > > display_error(ret); > > > > > > > > - while (!ret && (unw_step(&c) > 0) && max_stack--) { > > > > - unw_word_t ip; > > > > + if (callchain_param.order == ORDER_CALLEE) { > > > > + while (!ret && (unw_step(&c) > 0) && max_stack--) { > > > > + unw_word_t ip; > > > > > > > > - unw_get_reg(&c, UNW_REG_IP, &ip); > > > > - ret = ip ? entry(ip, ui->thread, cb, arg) : 0; > > > > + unw_get_reg(&c, UNW_REG_IP, &ip); > > > > + ret = ip ? entry(ip, ui->thread, cb, arg) : 0; > > > > + } > > > > + } else { > > > > + unw_word_t ips[max_stack]; > > > > + int i = 0; > > > > + > > > > + while ((unw_step(&c) > 0) && i < max_stack) { > > > > + unw_get_reg(&c, UNW_REG_IP, &ips[i]); > > > > + ++i; > > > > + } > > > > + max_stack = i; > > > > + for (i = max_stack - 1; i >= 0; --i) > > > > + entry(ips[i], ui->thread, cb, arg); > > > > there's no check for return value of entry callback > > > > also I wonder would it be better to store into ips[] within > > the single loop all the time, and iterate throught it after > > forward/backward based on the callchain_param.order > > > > please check attached patch, totaly untested, probably leaking some index > > ;-) > > > > any chance this could be done also for util/unwind-libdw.c ? > > That patch looks much better than mine. I'll try it out later next week and > will also have a look at util/unwind-libdw.c. Question: How can I test the So, you tried this patch, right? Jiri, have you submitted this in some other message I missed? - Arnaldo > behavior of the latter? Do I need to uninstall libunwind, or can I change the > unwinder at runtime somehow (env var?). > > Also, are there unit tests for this behavior somewhere? > -- > Milian Wolff | milian.wolff@kdab.com | Software Engineer > KDAB (Deutschland) GmbH&Co KG, a KDAB Group company > Tel: +49-30-521325470 > KDAB - The Qt Experts