From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-8.3 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_PASS,URIBL_BLOCKED, USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id A94C0C004D3 for ; Mon, 22 Oct 2018 10:16:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 5FA7520658 for ; Mon, 22 Oct 2018 10:16:22 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 5FA7520658 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=redhat.com Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728484AbeJVSeN (ORCPT ); Mon, 22 Oct 2018 14:34:13 -0400 Received: from mx1.redhat.com ([209.132.183.28]:44684 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727045AbeJVSeN (ORCPT ); Mon, 22 Oct 2018 14:34:13 -0400 Received: from smtp.corp.redhat.com (int-mx04.intmail.prod.int.phx2.redhat.com [10.5.11.14]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 05E2A3082125; Mon, 22 Oct 2018 10:16:20 +0000 (UTC) Received: from krava (unknown [10.43.17.150]) by smtp.corp.redhat.com (Postfix) with SMTP id CA2545DA67; Mon, 22 Oct 2018 10:16:18 +0000 (UTC) Date: Mon, 22 Oct 2018 12:16:18 +0200 From: Jiri Olsa To: Milian Wolff Cc: acme@kernel.org, jolsa@kernel.org, Linux-kernel@vger.kernel.org, linux-perf-users@vger.kernel.org Subject: Re: [PATCH 2/2] perf script: flush output stream after events in verbose mode Message-ID: <20181022101618.GH2452@krava> References: <20181021191424.16183-1-milian.wolff@kdab.com> <20181021191424.16183-2-milian.wolff@kdab.com> <20181022094317.GG2452@krava> <4444017.LnbBPIbh24@agathebauer> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4444017.LnbBPIbh24@agathebauer> User-Agent: Mutt/1.10.1 (2018-07-13) X-Scanned-By: MIMEDefang 2.79 on 10.5.11.14 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.42]); Mon, 22 Oct 2018 10:16:20 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Oct 22, 2018 at 12:09:22PM +0200, Milian Wolff wrote: > On Montag, 22. Oktober 2018 11:43:17 CEST Jiri Olsa wrote: > > On Sun, Oct 21, 2018 at 09:14:24PM +0200, Milian Wolff wrote: > > > When the perf script output is written to a terminal stream, > > > the normal output of `perf script` would get buffered, but its > > > debug output would be written directly. This made it quite hard > > > to figure out where a given debug output is coming from. We can > > > improve on this by flushing the output buffer after processing an > > > event. To see the value, compare the following output for a > > > `perf script -v` run: > > > > > > Before this patch: > > > ``` > > > unwind: reg 16, val 7faf7dfdc000 > > > unwind: reg 7, val 7ffc80811e30 > > > unwind: find_proc_info dso /usr/lib/ld-2.28.so > > > unwind: reg 6, val 0 > > > unwind: _start:ip = 0x7faf7dfdc000 (0x2000) > > > unwind: reg 16, val 7faf7dfdc000 > > > unwind: reg 7, val 7ffc80811e30 > > > unwind: find_proc_info dso /usr/lib/ld-2.28.so > > > unwind: reg 6, val 0 > > > unwind: _start:ip = 0x7faf7dfdc000 (0x2000) > > > unwind: reg 16, val 7faf7dfdc000 > > > unwind: reg 7, val 7ffc80811e30 > > > unwind: find_proc_info dso /usr/lib/ld-2.28.so > > > unwind: reg 6, val 0 > > > unwind: _start:ip = 0x7faf7dfdc000 (0x2000) > > > unwind: reg 16, val 7faf7dfdc000 > > > unwind: reg 7, val 7ffc80811e30 > > > ... lots and lots of verbose debug output > > > > > > cpp-inlining 24617 90229.122036534: 1 cycles:uppp: > > > 7faf7dfdc000 _start+0x0 (/usr/lib/ld-2.28.so) > > > > > > cpp-inlining 24617 90229.122043974: 1 cycles:uppp: > > > 7faf7dfdc000 _start+0x0 (/usr/lib/ld-2.28.so) > > > > > > ... > > > ``` > > > > > > After this patch: > > > ``` > > > ... > > > unwind: reg 16, val 7faf7dfdc000 > > > unwind: reg 7, val 7ffc80811e30 > > > unwind: find_proc_info dso /usr/lib/ld-2.28.so > > > unwind: reg 6, val 0 > > > unwind: _start:ip = 0x7faf7dfdc000 (0x2000) > > > > > > cpp-inlining 24617 90229.122036534: 1 cycles:uppp: > > > 7faf7dfdc000 _start+0x0 (/usr/lib/ld-2.28.so) > > > > > > unwind: reg 16, val 7faf7dfdc000 > > > unwind: reg 7, val 7ffc80811e30 > > > unwind: find_proc_info dso /usr/lib/ld-2.28.so > > > unwind: reg 6, val 0 > > > unwind: _start:ip = 0x7faf7dfdc000 (0x2000) > > > > > > cpp-inlining 24617 90229.122043974: 1 cycles:uppp: > > > 7faf7dfdc000 _start+0x0 (/usr/lib/ld-2.28.so) > > > > > > ... > > > ``` > > > > > > This new output format makes it much easier to use perf script > > > output for debugging purposes, e.g. to investigate broken dwarf > > > unwinding. > > > > yep, I plan to check on this ;-) > > > > > Signed-off-by: Milian Wolff > > > Cc: Arnaldo Carvalho de Melo > > > --- > > > > > > tools/perf/builtin-script.c | 3 +++ > > > 1 file changed, 3 insertions(+) > > > > > > diff --git a/tools/perf/builtin-script.c b/tools/perf/builtin-script.c > > > index bd468b90801b..ca09b7d2adb7 100644 > > > --- a/tools/perf/builtin-script.c > > > +++ b/tools/perf/builtin-script.c > > > @@ -1737,6 +1737,9 @@ static void process_event(struct perf_script > > > *script, > > > > > > if (PRINT_FIELD(METRIC)) > > > > > > perf_sample__fprint_metric(script, thread, evsel, sample, fp); > > > > > > + > > > + if (verbose) > > > + fflush(fp); > > > > should we call fflush(NULL) to dump all the streams? > > > > the verbose goes to stderr and fp seems to be stdout byt default > > stderr isn't buffered, so we don't need to flush it. So personally, I don't > see a need to dump all streams - fp should be enough? Can you maybe explain > where it would be required to flush more buffers? hum, did not know stderr wasn't buffer I think there's perf script feature to store the events data to separate files per each event.. but I guess we don't need to flush them.. we just need to have stdout and stderr in sync IIUC jirka