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=-20.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_SANE_1 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 B75AFC433E0 for ; Thu, 4 Mar 2021 01:21:45 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 860EB65230 for ; Thu, 4 Mar 2021 01:21:45 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236162AbhCDBVN (ORCPT ); Wed, 3 Mar 2021 20:21:13 -0500 Received: from szxga05-in.huawei.com ([45.249.212.191]:13466 "EHLO szxga05-in.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236199AbhCDBUZ (ORCPT ); Wed, 3 Mar 2021 20:20:25 -0500 Received: from DGGEMS408-HUB.china.huawei.com (unknown [172.30.72.58]) by szxga05-in.huawei.com (SkyGuard) with ESMTP id 4DrXzq4CSJzjTZL; Thu, 4 Mar 2021 09:17:59 +0800 (CST) Received: from [10.67.102.248] (10.67.102.248) by DGGEMS408-HUB.china.huawei.com (10.3.19.208) with Microsoft SMTP Server id 14.3.498.0; Thu, 4 Mar 2021 09:19:32 +0800 Subject: Re: [PATCH] perf record: Fix continue profiling after draining the buffer To: Arnaldo Carvalho de Melo CC: Jiri Olsa , Namhyung Kim , , Alexey Budankov , Adrian Hunter , Alexander Shishkin , Mark Rutland , Ingo Molnar , Peter Zijlstra , linux-kernel , References: <20210205065001.23252-1-yangjihong1@huawei.com> <5a76a82e-7ec1-d510-309e-a38a1b41027e@huawei.com> From: Yang Jihong Message-ID: Date: Thu, 4 Mar 2021 09:19:32 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.6.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset="utf-8"; format=flowed Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [10.67.102.248] X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2021/3/4 0:43, Arnaldo Carvalho de Melo wrote: > 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 > . > Thanks. Yang