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=-13.5 required=3.0 tests=INCLUDES_PATCH, MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,SIGNED_OFF_BY,SPF_PASS, 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 9DBA5C46463 for ; Tue, 20 Nov 2018 11:33:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6EC97208E4 for ; Tue, 20 Nov 2018 11:33:05 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 6EC97208E4 Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=kernel.org 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 S1729341AbeKTWBp (ORCPT ); Tue, 20 Nov 2018 17:01:45 -0500 Received: from lgeamrelo13.lge.com ([156.147.23.53]:35378 "EHLO lgeamrelo11.lge.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1729069AbeKTWBo (ORCPT ); Tue, 20 Nov 2018 17:01:44 -0500 Received: from unknown (HELO lgeamrelo01.lge.com) (156.147.1.125) by 156.147.23.53 with ESMTP; 20 Nov 2018 20:33:01 +0900 X-Original-SENDERIP: 156.147.1.125 X-Original-MAILFROM: namhyung@kernel.org Received: from unknown (HELO sejong) (10.177.227.17) by 156.147.1.125 with ESMTP; 20 Nov 2018 20:33:01 +0900 X-Original-SENDERIP: 10.177.227.17 X-Original-MAILFROM: namhyung@kernel.org Date: Tue, 20 Nov 2018 20:33:00 +0900 From: Namhyung Kim To: Jiri Olsa Cc: Arnaldo Carvalho de Melo , lkml , Ingo Molnar , Alexander Shishkin , Peter Zijlstra , David Miller , kernel-team@lge.com Subject: Re: [PATCH 05/12] perf top: Moving lost events warning to helpline Message-ID: <20181120113300.GG20153@sejong> References: <20181119122016.22423-1-jolsa@kernel.org> <20181119122016.22423-6-jolsa@kernel.org> <20181120020421.GE20153@sejong> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <20181120020421.GE20153@sejong> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Nov 20, 2018 at 11:04:21AM +0900, Namhyung Kim wrote: > On Mon, Nov 19, 2018 at 01:20:09PM +0100, Jiri Olsa wrote: > > We can't display the UI box saying that we are slow in reader > > thread. That will make perf top even slower and user even more > > angry ;-) > > > > Moving the UI box message out of the reader thread into UI thread > > and changing it into helpline, so there's no 'press any key' > > necessary. > > > > Link: http://lkml.kernel.org/n/tip-0rpmmt3omlait889ewp1cl61@git.kernel.org > > Signed-off-by: Jiri Olsa > > --- > > tools/perf/builtin-top.c | 16 +++++----------- > > 1 file changed, 5 insertions(+), 11 deletions(-) > > > > diff --git a/tools/perf/builtin-top.c b/tools/perf/builtin-top.c > > index 047e99de09f3..1d77aa7650da 100644 > > --- a/tools/perf/builtin-top.c > > +++ b/tools/perf/builtin-top.c > > @@ -553,8 +553,6 @@ static void perf_top__sort_new_samples(void *arg) > > struct perf_evsel *evsel = t->sym_evsel; > > struct hists *hists; > > > > - perf_top__reset_sample_counters(t); > > - > > if (t->evlist->selected != NULL) > > t->sym_evsel = t->evlist->selected; > > > > @@ -571,6 +569,11 @@ static void perf_top__sort_new_samples(void *arg) > > > > hists__collapse_resort(hists, NULL); > > perf_evsel__output_resort(evsel, NULL); > > + > > + if (t->lost) > > + ui_helpline__fpush("Too slow to read ring buffer (change period (-c/-F) or limit CPUs (-C)\n"); > > In general, ui_helpline__[f]push() requires corresponding __pop() > which handles timeout logic (or something can dismiss the message). > The ui_helpline__show() is to show the message and overwrite the old > one. > > But we don't use it strictly and I think just pr_err() or pr_warning() > is ok here (which call ui_helpline__show() internally). > > Anyway, I found that tui_helpline__push() should use ui__lock. > Otherwise it could race with display thread and break rendering. > A bug from the beginning but no one reported... :) Hmm.. wait. it caused a deadlock since it calls itself internally.. Will take a deeper look at it.. Thanks, Namhyung