Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755466AbbKRJZh (ORCPT ); Wed, 18 Nov 2015 04:25:37 -0500 Received: from mail-pa0-f50.google.com ([209.85.220.50]:35528 "EHLO mail-pa0-f50.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755391AbbKRJZ2 (ORCPT ); Wed, 18 Nov 2015 04:25:28 -0500 User-Agent: K-9 Mail for Android In-Reply-To: <20151118082525.GC5416@krava.brq.redhat.com> References: <1447772739-18471-1-git-send-email-jolsa@kernel.org> <1447772739-18471-3-git-send-email-jolsa@kernel.org> <564BFAD4.8060909@huawei.com> <20151118054114.GQ7062@sejong> <20151118082525.GC5416@krava.brq.redhat.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Content-Type: text/plain; charset=UTF-8 Subject: Re: [PATCH 2/3] perf tools: Add callchain order support for libunwind DWARF unwinder From: Namhyung Kim Date: Wed, 18 Nov 2015 18:25:15 +0900 To: Jiri Olsa , Namhyung Kim CC: "Wangnan (F)" , Jiri Olsa , Arnaldo Carvalho de Melo , lkml , David Ahern , Peter Zijlstra , Ingo Molnar , Milian Wolff Message-ID: Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1739 Lines: 55 On November 18, 2015 5:25:25 PM GMT+09:00, Jiri Olsa wrote: >On Wed, Nov 18, 2015 at 02:41:14PM +0900, Namhyung Kim wrote: > >SNIP > >> > I'm not sure whether we can regard this behavior changing as a >bugfix? I >> > think >> > there may be some reason the original code explicitly avoid >creating an '0' >> > entry. >> >> I think callchain value being 0 is an error or marker for the end of >> callchain. So it'd be better avoiding 0 entry. >> >> But unfortunately, we have many 0 entries (and broken callchain after >> them) with fp recording on optimized binaries. I think we should >omit >> those callchains. >> >> Maybe something like this? >> >> >> >> diff --git a/tools/perf/util/machine.c b/tools/perf/util/machine.c >> index 5ef90be2a249..22642c5719ab 100644 >> --- a/tools/perf/util/machine.c >> +++ b/tools/perf/util/machine.c >> @@ -1850,6 +1850,15 @@ static int >thread__resolve_callchain_sample(struct thread *thread, >> #endif >> ip = chain->ips[j]; >> >> + /* callchain value inside zero page means it's broken, stop */ >> + if (ip < 4096) { >> + if (callchain_param.order == ORDER_CALLER) { >> + callchain_cursor_reset(&callchain_cursor); > >hum, do we want to throw away whatever we have till now? For caller order, yes. For callee order, everything after 0 value is garbage. So we need to discard any chains before the 0 for caller IMHO. Thanks Namhyung -- Sent from my Android device with K-9 Mail. Please excuse my brevity. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/