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=-17.0 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT 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 C6455C433E0 for ; Mon, 21 Dec 2020 07:01:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 873A022CA1 for ; Mon, 21 Dec 2020 07:01:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726244AbgLUHBb (ORCPT ); Mon, 21 Dec 2020 02:01:31 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:58334 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725995AbgLUHBa (ORCPT ); Mon, 21 Dec 2020 02:01:30 -0500 Received: from mail-pl1-x636.google.com (mail-pl1-x636.google.com [IPv6:2607:f8b0:4864:20::636]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id B914FC061282 for ; Sun, 20 Dec 2020 23:00:50 -0800 (PST) Received: by mail-pl1-x636.google.com with SMTP id j1so5139551pld.3 for ; Sun, 20 Dec 2020 23:00:50 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=sender:from:to:cc:subject:date:message-id:in-reply-to:references :mime-version:content-transfer-encoding; bh=LbGmfh+nRo/KTGqtMjiPUReI82gu/mZcXbqano76A2o=; b=q541JWr6u5Rwjy5rWh/OE9fNlL59nmcKzMt3hOMCwTj4KUkXYAj1OzUclf7lEkYgO9 6W1FoM2XO6F3lP6CoRPsbDODN8OZ5IyRcOnlHbflIReLxse9UsKn0qQ3rCs6zxHG7dOu NEcEHwCgZi2LN2Kg6tYE7fzGmzxf6r58GrxGFn+MlRRJVxrySwmQS0NVbcBray766aUz /+b4eswpjEGiQ0aAsEZ6hWMHiDQo5UD9NSlsMt6fP1yc0NtxdPHhS+m6kaHeBgTiehLl Ac4S8aCkIsjg7pLDa+mW7QgeZxGHFbJK+OlA1F+1CCoQAolLJ92NE3ZfRzG7qLMxQCba zgTQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:sender:from:to:cc:subject:date:message-id :in-reply-to:references:mime-version:content-transfer-encoding; bh=LbGmfh+nRo/KTGqtMjiPUReI82gu/mZcXbqano76A2o=; b=Sk0KnYYgFNczkz84lRIX3VgZ9zltma1nAR743PJc1L9dLskLYiBpuhjpfftG1iuxhT +qtKMnvc3xbKQV6MVWBnBQN3F62iPIoHC0KlCDDMwDeAcykCXsYOofNtZIqm/e30Hfdq NqJ9ajmwuqwr903OdNotYvsYj8vWy3q5aoAVSO4RMwQX83fe6FAjhX5KHiNUzkeBAIm2 R1QMPKIqG8Pzbj7kKMzU0fpAFqZVQRwYKECuzunKPej4l1mwtb3BpjxYYVTiykXYkPfa /WlEc5LuNqehW/F97OBc6L0dpyFxkmZcJtn2OMyQsW2uNBPYLjLPmU1T/L4MklzmfgqU Ktzg== X-Gm-Message-State: AOAM5326HZ7fhHcyKccWPbIdiYbMNSw6AYIe8eZGwDGePTPF5nrtoZcd g0mymsvxJ1O9bC/EMLG95ks= X-Google-Smtp-Source: ABdhPJw6/LThwLKV1i8pencELO4lbcdg0MwrDQatGHOeUw8NTNtcrckz+SOFRX/JpOVOQiCpiUrSBw== X-Received: by 2002:a17:90a:1748:: with SMTP id 8mr15954114pjm.47.1608534050351; Sun, 20 Dec 2020 23:00:50 -0800 (PST) Received: from balhae.roam.corp.google.com ([101.235.31.111]) by smtp.gmail.com with ESMTPSA id p22sm16421131pgk.21.2020.12.20.23.00.37 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 20 Dec 2020 23:00:49 -0800 (PST) Sender: Namhyung Kim From: Namhyung Kim To: Arnaldo Carvalho de Melo , Jiri Olsa Cc: Ingo Molnar , Peter Zijlstra , Mark Rutland , Alexander Shishkin , LKML , Stephane Eranian , Andi Kleen , Ian Rogers Subject: [PATCH 1/3] perf tools: Use /proc//task//status for synthesis Date: Mon, 21 Dec 2020 16:00:27 +0900 Message-Id: <20201221070029.1451176-2-namhyung@kernel.org> X-Mailer: git-send-email 2.29.2.684.gfbc64c5ab5-goog In-Reply-To: <20201221070029.1451176-1-namhyung@kernel.org> References: <20201221070029.1451176-1-namhyung@kernel.org> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org To save memory usage, it needs to reduce number of entries in the proc filesystem. It's using /proc//task directory to traverse threads in the process and then kernel creates /proc//task/ entries. After that it checks the thread info using the /proc//status file rather than /proc//task//status. As far as I can see, they are the same and contain all the info we need. Using the latter eliminates the unnecessary /proc/ entry. This can be useful especially a large number of threads are used in the system. In my experiment around 1KB of memory on average was saved for each thread (which is not a thread group leader). To do this, pass both pid and tid to perf_event_prepare_comm() if it knows them. In case it doesn't know, passing 0 as pid will do the old way. Signed-off-by: Namhyung Kim --- tools/perf/util/synthetic-events.c | 30 +++++++++++++++++++----------- 1 file changed, 19 insertions(+), 11 deletions(-) diff --git a/tools/perf/util/synthetic-events.c b/tools/perf/util/synthetic-events.c index 2947e3f3c6d9..515d145a4303 100644 --- a/tools/perf/util/synthetic-events.c +++ b/tools/perf/util/synthetic-events.c @@ -69,7 +69,7 @@ int perf_tool__process_synth_event(struct perf_tool *tool, * Assumes that the first 4095 bytes of /proc/pid/stat contains * the comm, tgid and ppid. */ -static int perf_event__get_comm_ids(pid_t pid, char *comm, size_t len, +static int perf_event__get_comm_ids(pid_t pid, pid_t tid, char *comm, size_t len, pid_t *tgid, pid_t *ppid) { char bf[4096]; @@ -81,7 +81,10 @@ static int perf_event__get_comm_ids(pid_t pid, char *comm, size_t len, *tgid = -1; *ppid = -1; - snprintf(bf, sizeof(bf), "/proc/%d/status", pid); + if (pid) + snprintf(bf, sizeof(bf), "/proc/%d/task/%d/status", pid, tid); + else + snprintf(bf, sizeof(bf), "/proc/%d/status", tid); fd = open(bf, O_RDONLY); if (fd < 0) { @@ -93,7 +96,7 @@ static int perf_event__get_comm_ids(pid_t pid, char *comm, size_t len, close(fd); if (n <= 0) { pr_warning("Couldn't get COMM, tigd and ppid for pid %d\n", - pid); + tid); return -1; } bf[n] = '\0'; @@ -116,27 +119,32 @@ static int perf_event__get_comm_ids(pid_t pid, char *comm, size_t len, memcpy(comm, name, size); comm[size] = '\0'; } else { - pr_debug("Name: string not found for pid %d\n", pid); + pr_debug("Name: string not found for pid %d\n", tid); } if (tgids) { tgids += 5; /* strlen("Tgid:") */ *tgid = atoi(tgids); + + if (pid && pid != *tgid) { + pr_debug("Tgid: not match to given pid: %d vs %d\n", + pid, *tgid); + } } else { - pr_debug("Tgid: string not found for pid %d\n", pid); + pr_debug("Tgid: string not found for pid %d\n", tid); } if (ppids) { ppids += 5; /* strlen("PPid:") */ *ppid = atoi(ppids); } else { - pr_debug("PPid: string not found for pid %d\n", pid); + pr_debug("PPid: string not found for pid %d\n", tid); } return 0; } -static int perf_event__prepare_comm(union perf_event *event, pid_t pid, +static int perf_event__prepare_comm(union perf_event *event, pid_t pid, pid_t tid, struct machine *machine, pid_t *tgid, pid_t *ppid) { @@ -147,7 +155,7 @@ static int perf_event__prepare_comm(union perf_event *event, pid_t pid, memset(&event->comm, 0, sizeof(event->comm)); if (machine__is_host(machine)) { - if (perf_event__get_comm_ids(pid, event->comm.comm, + if (perf_event__get_comm_ids(pid, tid, event->comm.comm, sizeof(event->comm.comm), tgid, ppid) != 0) { return -1; @@ -168,7 +176,7 @@ static int perf_event__prepare_comm(union perf_event *event, pid_t pid, event->comm.header.size = (sizeof(event->comm) - (sizeof(event->comm.comm) - size) + machine->id_hdr_size); - event->comm.tid = pid; + event->comm.tid = tid; return 0; } @@ -180,7 +188,7 @@ pid_t perf_event__synthesize_comm(struct perf_tool *tool, { pid_t tgid, ppid; - if (perf_event__prepare_comm(event, pid, machine, &tgid, &ppid) != 0) + if (perf_event__prepare_comm(event, 0, pid, machine, &tgid, &ppid) != 0) return -1; if (perf_tool__process_synth_event(tool, event, machine, process) != 0) @@ -701,7 +709,7 @@ static int __event__synthesize_thread(union perf_event *comm_event, continue; rc = -1; - if (perf_event__prepare_comm(comm_event, _pid, machine, + if (perf_event__prepare_comm(comm_event, pid, _pid, machine, &tgid, &ppid) != 0) break; -- 2.29.2.684.gfbc64c5ab5-goog