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=-21.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED 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 13734C28E86 for ; Wed, 3 Mar 2021 19:28:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B2A1A64EF4 for ; Wed, 3 Mar 2021 19:28:10 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1579735AbhCCSb4 (ORCPT ); Wed, 3 Mar 2021 13:31:56 -0500 Received: from mail.kernel.org ([198.145.29.99]:39292 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S241307AbhCCQow (ORCPT ); Wed, 3 Mar 2021 11:44:52 -0500 Received: by mail.kernel.org (Postfix) with ESMTPSA id C591964E6F; Wed, 3 Mar 2021 16:43:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1614789811; bh=EupOo0dBtxON4TALIiJGGoqFuZoXf9llA6hE2Cv4p1E=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=mAZZjaiv5NeSmKkmqImyi/McoXryvtx8MumfSLCuy9vg6WZyY2WpYATkJGI80BwoN eFNn+ZjjHJYXCOH+VGEydAZN7IG9F+xR6dgF0fk64XB1WeCzaYl0NuWME1NsqIeXq5 LQMjpahg59Gp5pKAWNqD7jvNjb6R+ohlC0PBhr4DXl2nWYyftNsH6GiOxV1gUiSjgd vKEgI0kIG4u4JXFDIA8KbBpR1BIDovvzdSGdkvsuYmM8dgI2x2h39DfGWesroQi/M+ K8NNNEtXrbcTlujXHK3W+V6qv3BlxH1ZYixdTApz6OAdr0wY0PMcmK/VATNRq/PhmJ u94YnOnmb9bzg== Received: by quaco.ghostprotocols.net (Postfix, from userid 1000) id B87E84038F; Wed, 3 Mar 2021 13:43:27 -0300 (-03) Date: Wed, 3 Mar 2021 13:43:27 -0300 From: Arnaldo Carvalho de Melo To: Yang Jihong Cc: Jiri Olsa , Namhyung Kim , amistry@google.com, Alexey Budankov , Adrian Hunter , Alexander Shishkin , Mark Rutland , Ingo Molnar , Peter Zijlstra , linux-kernel , zhangjinhao2@huawei.com Subject: Re: [PATCH] perf record: Fix continue profiling after draining the buffer Message-ID: References: <20210205065001.23252-1-yangjihong1@huawei.com> <5a76a82e-7ec1-d510-309e-a38a1b41027e@huawei.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <5a76a82e-7ec1-d510-309e-a38a1b41027e@huawei.com> X-Url: http://acmel.wordpress.com Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Em Mon, Feb 22, 2021 at 09:31:51AM +0800, Yang Jihong escreveu: > Hello, > > On 2021/2/19 1:09, Arnaldo Carvalho de Melo wrote: > > Em Thu, Feb 18, 2021 at 10:20:53AM -0300, Arnaldo Carvalho de Melo escreveu: > > > Em Fri, Feb 05, 2021 at 11:46:12AM +0100, Jiri Olsa escreveu: > > > > On Fri, Feb 05, 2021 at 07:35:22PM +0900, Namhyung Kim wrote: > > > > > Hello, > > > > > > > > > > On Fri, Feb 5, 2021 at 3:50 PM Yang Jihong wrote: > > > > > > > > > > > > commit da231338ec9c098707c8a1e4d8a50e2400e2fe17 uses eventfd to solve rare race > > > > > > where the setting and checking of 'done' which add done_fd to pollfd. > > > > > > When draining buffer, revents of done_fd is 0 and evlist__filter_pollfd > > > > > > function returns a non-zero value. > > > > > > As a result, perf record does not stop profiling. > > > > > > > > > > > > The following simple scenarios can trigger this condition: > > > > > > > > > > > > sleep 10 & > > > > > > perf record -p $! > > > > > > > > > > > > After the sleep process exits, perf record should stop profiling and exit. > > > > > > However, perf record keeps running. > > > > > > > > > > > > If pollfd revents contains only POLLERR or POLLHUP, > > > > > > perf record indicates that buffer is draining and need to stop profiling. > > > > > > Use fdarray_flag__nonfilterable to set done eventfd to nonfilterable objects, > > > > > > so that evlist__filter_pollfd does not filter and check done eventfd. > > > > > > > > > > > > Fixes: da231338ec9c (perf record: Use an eventfd to wakeup when done) > > > > > > Signed-off-by: Yang Jihong > > > > > > --- > > > > > > tools/perf/builtin-record.c | 2 +- > > > > > > tools/perf/util/evlist.c | 8 ++++++++ > > > > > > tools/perf/util/evlist.h | 4 ++++ > > > > > > 3 files changed, 13 insertions(+), 1 deletion(-) > > > > > > > > > > > > diff --git a/tools/perf/builtin-record.c b/tools/perf/builtin-record.c > > > > > > index fd3911650612..51e593e896ea 100644 > > > > > > --- a/tools/perf/builtin-record.c > > > > > > +++ b/tools/perf/builtin-record.c > > > > > > @@ -1663,7 +1663,7 @@ static int __cmd_record(struct record *rec, int argc, const char **argv) > > > > > > status = -1; > > > > > > goto out_delete_session; > > > > > > } > > > > > > - err = evlist__add_pollfd(rec->evlist, done_fd); > > > > > > + err = evlist__add_wakeup_eventfd(rec->evlist, done_fd); > > > > > > if (err < 0) { > > > > > > pr_err("Failed to add wakeup eventfd to poll list\n"); > > > > > > status = err; > > > > > > diff --git a/tools/perf/util/evlist.c b/tools/perf/util/evlist.c > > > > > > index 05363a7247c4..fea4c1e8010d 100644 > > > > > > --- a/tools/perf/util/evlist.c > > > > > > +++ b/tools/perf/util/evlist.c > > > > > > @@ -572,6 +572,14 @@ int evlist__filter_pollfd(struct evlist *evlist, short revents_and_mask) > > > > > > return perf_evlist__filter_pollfd(&evlist->core, revents_and_mask); > > > > > > } > > > > > > > > > > > > +#ifdef HAVE_EVENTFD_SUPPORT > > > > > > +int evlist__add_wakeup_eventfd(struct evlist *evlist, int fd) > > > > > > +{ > > > > > > + return perf_evlist__add_pollfd(&evlist->core, fd, NULL, POLLIN, > > > > > > + fdarray_flag__nonfilterable); > > > > > > +} > > > > > > +#endif > > > > > > > > > > Does it build when HAVE_EVENTFD_SUPPORT is not defined? > > > > > > > > yea, I was wondering the same.. but it's called only from > > > > code within HAVE_EVENTFD_SUPPORT ifdef > > > > > > Yes, this can't work on systems without eventfd, it will simply not > > > build, and why do we have to make the definition of this function > > > conditional on HAVE_EVENTFD_SUPPORT? > > > > > > I'm missing something :-\ > > > > > > Yeah, this whole call to evlist__add_pollfd is already surrounded by > > > #ifdef HAVE_EVENTFD_SUPPORT: > > > > > > 1656 if (zstd_init(&session->zstd_data, rec->opts.comp_level) < 0) { > > > 1657 pr_err("Compression initialization failed.\n"); > > > 1658 return -1; > > > 1659 } > > > 1660 #ifdef HAVE_EVENTFD_SUPPORT > > > 1661 done_fd = eventfd(0, EFD_NONBLOCK); > > > 1662 if (done_fd < 0) { > > > 1663 pr_err("Failed to create wakeup eventfd, error: %m\n"); > > > 1664 status = -1; > > > 1665 goto out_delete_session; > > > 1666 } > > > 1667 err = evlist__add_pollfd(rec->evlist, done_fd); > > > 1668 if (err < 0) { > > > 1669 pr_err("Failed to add wakeup eventfd to poll list\n"); > > > 1670 status = err; > > > 1671 goto out_delete_session; > > > 1672 } > > > 1673 #endif // HAVE_EVENTFD_SUPPORT > > > 1674 > > > 1675 session->header.env.comp_type = PERF_COMP_ZSTD; > > > 1676 session->header.env.comp_level = rec->opts.comp_level; > > > > > > Jiri, does your Acked-by stands? Namhyung? > > > > Thanks tested and applied, together with Jiri's Tested-by, > > > > - Arnaldo > > . > > > Is this patch okay? Is there anything that needs to be modified? It was merged: https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/commit/tools/perf/builtin-record.c?id=e16c2ce7c5ed5de881066c1fd10ba5c09af69559 - Arnaldo