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=-5.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE, SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=no 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 B14AAC4361B for ; Wed, 16 Dec 2020 07:55:44 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 5367023356 for ; Wed, 16 Dec 2020 07:55:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726109AbgLPHzn (ORCPT ); Wed, 16 Dec 2020 02:55:43 -0500 Received: from frasgout.his.huawei.com ([185.176.79.56]:2263 "EHLO frasgout.his.huawei.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726095AbgLPHzn (ORCPT ); Wed, 16 Dec 2020 02:55:43 -0500 Received: from fraeml712-chm.china.huawei.com (unknown [172.18.147.206]) by frasgout.his.huawei.com (SkyGuard) with ESMTP id 4CwnPb36Llz67QjZ; Wed, 16 Dec 2020 15:51:15 +0800 (CST) Received: from lhreml741-chm.china.huawei.com (10.201.108.191) by fraeml712-chm.china.huawei.com (10.206.15.61) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2106.2; Wed, 16 Dec 2020 08:54:56 +0100 Received: from [10.47.203.173] (10.47.203.173) by lhreml741-chm.china.huawei.com (10.201.108.191) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.2106.2; Wed, 16 Dec 2020 07:54:49 +0000 Subject: Re: [PATCH 4/8] perf daemon: Add daemon command To: Jiri Olsa CC: Jiri Olsa , Arnaldo Carvalho de Melo , lkml , Peter Zijlstra , Ingo Molnar , Mark Rutland , "Namhyung Kim" , Alexander Shishkin , Michael Petlan , Ian Rogers , Stephane Eranian References: <20201212104358.412065-1-jolsa@kernel.org> <20201212104358.412065-5-jolsa@kernel.org> <1e467abe-4613-765f-5138-6215b711f9fb@huawei.com> <20201215194354.GH698181@krava> From: Alexei Budankov Message-ID: Date: Wed, 16 Dec 2020 10:54:43 +0300 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.5.1 MIME-Version: 1.0 In-Reply-To: <20201215194354.GH698181@krava> Content-Type: text/plain; charset="utf-8" Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [10.47.203.173] X-ClientProxiedBy: braeml703-chm.china.huawei.com (10.226.71.47) To lhreml741-chm.china.huawei.com (10.201.108.191) X-CFilter-Loop: Reflected Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 15.12.2020 22:43, Jiri Olsa wrote: > On Tue, Dec 15, 2020 at 06:40:26PM +0300, Alexei Budankov wrote: >> Hi, >> >> On 12.12.2020 13:43, Jiri Olsa wrote: >>> Adding daemon command that allows to run record sessions >>> on background. Each session represents one perf record >>> process and is configured in config file. >>> >>> Example: >>> >>> # cat config.daemon >>> [daemon] >>> base=/opt/perfdata >> >> It could probably make sense to consider using locations at /var/ >> directory, similar to other already existing daemon processes in >> system so admin and user experience would be easily reusabe for >> performance monitoring daemon (service). > > hm, you can specify any /var path in there if you like, > do you suggest to hardcode it? This thing: https://en.wikipedia.org/wiki/Filesystem_Hierarchy_Standard Since Perf is a part of OS it would better use some standardized locations. > >> >>> >>> [session-1] >>> run = -m 10M -e cycles -o /opt/perfdata/1/perf.data --overwrite --switch-output -a >>> >>> [session-2] >>> run = -m 20M -e sched:* -o /opt/perfdata/2/perf.data --overwrite --switch-output -a >>> >>> Default perf config has the same daemon base: >>> >>> # cat ~/.perfconfig >>> [daemon] >>> base=/opt/perfdata >>> >>> Starting the daemon: >>> >>> # perf daemon --config config.daemon >> >> It could make sense to name daemon config file similar to .perfconfig >> e.g. like .perfconfig.daemon. perf daemon command would then assume, by >> default, usage of .perfconfig.daemon config or the one specified on the >> command line via --config option. It also would be helpfull have loaded >> config file path printed into console: >> # perf daemon >> Daemon process started with config /path/to/.perfconfig.daemon > > so the current way is, that following creates daemon: > > # perf daemon --config > > and any other 'non --config' option' is used to 'query/control' daemon: > > # perf daemon > # perf daemon --signal > # perf daemon --stop > ... > > > I'd like to keep short way checking on daemon, without too many > options, like: > > # perf daemon > [690174:daemon] base: /opt/perfdata > [690175:top] perf record -e cycles --switch-output=1m --switch-max-files=6 -a > > > I think maybe we don't need any other .perfconfig, we could have > all in standard .perfconfig, like: > > # cat .perfconfig: > [daemon] > base=/opt/perfdata > > [session-1] > run = -m 1M -e cycles --overwrite --switch-output -a > [session-2] > run = -m 1M -e sched:* --overwrite --switch-output -a > > > and to run daemon on top of it: > > # perf daemon --start > > > to run daemon with alternate config: > > # perf daemon --start= > > or: > > # perf daemon --start --config= > > > and checking on daemon with default .perfconfig setup: > > # perf daemon > > > checking on daemon with different base or config: > > # perf daemon --base= > # perf daemon --config= > # perf daemon --base= --stop > # perf daemon --base= --signal > # perf daemon --config= --stop > # perf daemon --config= --signal > > how about that? Extending .perfconfig would look simpler for users, IHMO. It looks like --base option actually implements --sandbox or similar semantics. > > SNIP > >>> +static struct session* >>> +daemon__find_session(struct daemon *daemon, char *name) >>> +{ >>> + struct session *session; >>> + >>> + list_for_each_entry(session, &daemon->sessions, list) { >>> + if (!strcmp(session->name, name)) >>> + return session; >>> + } >>> + >>> + return NULL; >>> +} >>> + >>> +static int session_name(const char *var, char *session, int len) >> >> should possibly name it get_session_name. > > ok > >> >>> +{ >>> + const char *p = var + sizeof("session-") - 1; >> >> should possibly check that p still points inside [var, var+len). > > ok > > SNIP > >>> +static int session__wait(struct session *session, struct daemon *daemon, >>> + int secs) >>> +{ >>> + time_t current, start = 0; >>> + int cnt; >>> + >>> + start = current = time(NULL); >>> + >>> + do { >>> + usleep(500); >> >> This polling design is actually sub-optimal because it induces redundant >> noise in a system. Ideally it should be implemented in async fashion so >> kernel would atomically notify daemon process on event happened in some >> of record processes e.g. using of poll-like() system call. > > ok, any suggestion? Possibly, checking SIGCHLDs via signalfd [1] OR using pidfd [2] on kernel v5.3+ [1] https://man7.org/linux/man-pages/man2/signalfd.2.html [2] https://man7.org/linux/man-pages/man2/pidfd_open.2.html Thanks, Alexei > >> >>> + cnt = session__check(session, daemon); >>> + if (cnt) >>> + break; >>> + >>> + current = time(NULL); >>> + } while ((start + secs > current)); >>> + >>> + return cnt; >>> +} >>> + >>> +static int session__signal(struct session *session, int sig) >>> +{ >>> + if (session->pid < 0) >>> + return -1; >>> + return kill(session->pid, sig); >> >> "Better" alternative could possibly be sending of some 'stop' command >> via --control=fd. > > true, nice idea.. seems more clean and we already have control fd open > > will add it to next version > > thanks, > jirka > > . >