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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 1E0F7C001DF for ; Sat, 21 Oct 2023 01:47:46 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229705AbjJUBrp (ORCPT ); Fri, 20 Oct 2023 21:47:45 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49966 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229518AbjJUBrn (ORCPT ); Fri, 20 Oct 2023 21:47:43 -0400 Received: from szxga02-in.huawei.com (szxga02-in.huawei.com [45.249.212.188]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 0ECD3D7A; Fri, 20 Oct 2023 18:47:38 -0700 (PDT) Received: from kwepemm000003.china.huawei.com (unknown [172.30.72.53]) by szxga02-in.huawei.com (SkyGuard) with ESMTP id 4SC43n6PLHzNnGr; Sat, 21 Oct 2023 09:43:33 +0800 (CST) Received: from [10.67.111.205] (10.67.111.205) by kwepemm000003.china.huawei.com (7.193.23.66) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2507.31; Sat, 21 Oct 2023 09:47:34 +0800 Subject: Re: [PATCH] perf data: Increase RLIMIT_NOFILE limit when open too many files in perf_data__create_dir() To: Namhyung Kim CC: , , , , , , , , , References: <20231013075945.698874-1-yangjihong1@huawei.com> From: Yang Jihong Message-ID: <70653005-d149-6ecf-b2fb-93a77376a504@huawei.com> Date: Sat, 21 Oct 2023 09:47:33 +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: 8bit X-Originating-IP: [10.67.111.205] X-ClientProxiedBy: dggems703-chm.china.huawei.com (10.3.19.180) To kwepemm000003.china.huawei.com (7.193.23.66) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hello, On 2023/10/20 13:59, Namhyung Kim wrote: > Hello, > > On Fri, Oct 13, 2023 at 1:01 AM Yang Jihong wrote: >> >> If using parallel threads to collect data, perf record needs at least 6 fds >> per CPU. (one for sys_perf_event_open, four for pipe msg and ack of the >> pipe, see record__thread_data_open_pipes(), and one for open perf.data.XXX) > > Yep, probably one more for the dummy event. > >> For an environment with more than 100 cores, if perf record uses both >> `-a` and `--threads` options, it is easy to exceed the upper limit of the >> file descriptor number, when we run out of them try to increase the limits. >> >> Before: >> $ ulimit -n >> 1024 >> $ lscpu | grep 'On-line CPU(s)' >> On-line CPU(s) list: 0-159 >> $ perf record --threads -a sleep 1 >> Failed to create data directory: Too many open files >> >> After: >> $ ulimit -n >> 1024 >> $ lscpu | grep 'On-line CPU(s)' >> On-line CPU(s) list: 0-159 >> $ perf record --threads -a sleep 1 >> [ perf record: Woken up 1 times to write data ] >> [ perf record: Captured and wrote 0.394 MB perf.data (1576 samples) ] >> Signed-off-by: Yang Jihong >> --- >> tools/perf/util/data.c | 12 ++++++++++++ >> 1 file changed, 12 insertions(+) >> >> diff --git a/tools/perf/util/data.c b/tools/perf/util/data.c >> index fc16299c915f..098f9e3bb2e7 100644 >> --- a/tools/perf/util/data.c >> +++ b/tools/perf/util/data.c >> @@ -17,6 +17,7 @@ >> #include "util.h" // rm_rf_perf_data() >> #include "debug.h" >> #include "header.h" >> +#include "evsel.h" >> #include >> >> static void close_dir(struct perf_data_file *files, int nr) >> @@ -35,6 +36,7 @@ void perf_data__close_dir(struct perf_data *data) >> >> int perf_data__create_dir(struct perf_data *data, int nr) >> { >> + enum rlimit_action set_rlimit = NO_CHANGE; >> struct perf_data_file *files = NULL; >> int i, ret; >> >> @@ -54,11 +56,21 @@ int perf_data__create_dir(struct perf_data *data, int nr) >> goto out_err; >> } >> >> +retry_open: >> ret = open(file->path, O_RDWR|O_CREAT|O_TRUNC, S_IRUSR|S_IWUSR); >> if (ret < 0) { >> + /* >> + * If using parallel threads to collect data, >> + * perf record needs at least 6 fds per CPU. >> + * When we run out of them try to increase the limits. >> + */ >> + if (errno == EMFILE && evsel__increase_rlimit(&set_rlimit)) > > It seems weird that we have this helper with evsel prefix and > it does nothing with evsel. But it's a separate concern, so > > Acked-by: Namhyung Kim Thanks for the Acked-by tag. Uh... The name of this helper doesn't seem to be appropriate. Okay, I'll submit a patch to fix this helper name. Thanks, Yang