From patchwork Wed Sep 2 02:31:12 2020 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Yonghong Song X-Patchwork-Id: 261659 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=-13.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH, MAILING_LIST_MULTI, SIGNED_OFF_BY, 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 41FBBC433E2 for ; Wed, 2 Sep 2020 02:31:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0F6A5206F0 for ; Wed, 2 Sep 2020 02:31:25 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=fb.com header.i=@fb.com header.b="o4Zj6Eor" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726247AbgIBCbX (ORCPT ); Tue, 1 Sep 2020 22:31:23 -0400 Received: from mx0a-00082601.pphosted.com ([67.231.145.42]:6982 "EHLO mx0a-00082601.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726122AbgIBCbX (ORCPT ); Tue, 1 Sep 2020 22:31:23 -0400 Received: from pps.filterd (m0044010.ppops.net [127.0.0.1]) by mx0a-00082601.pphosted.com (8.16.0.42/8.16.0.42) with SMTP id 0822UDpV026137 for ; Tue, 1 Sep 2020 19:31:23 -0700 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=fb.com; h=from : to : cc : subject : date : message-id : in-reply-to : references : mime-version : content-transfer-encoding : content-type; s=facebook; bh=mq0ef9jOqeU3dqaAcGpJaqz/OttVubZ/GMgdk24nemU=; b=o4Zj6EorNZ8UeAlGKIuwyxMpuzkzJk9wyKsdNvU49bth+yHZ+KO6tnQSquxEFDt2OaIQ 040pzK9o04llFZlISGxbHTwL9CFmzn/9UavjIBw7AhRpdnThIbDfmuCRlLWCf5O57ms8 ARQp87fL3RygKoorXnO6jIzsnfzHzwSEjYE= Received: from mail.thefacebook.com ([163.114.132.120]) by mx0a-00082601.pphosted.com with ESMTP id 339ws49d88-3 (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128 verify=NOT) for ; Tue, 01 Sep 2020 19:31:22 -0700 Received: from intmgw005.03.ash8.facebook.com (2620:10d:c085:208::f) by mail.thefacebook.com (2620:10d:c085:11d::5) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_GCM_SHA256) id 15.1.1979.3; Tue, 1 Sep 2020 19:31:22 -0700 Received: by devbig003.ftw2.facebook.com (Postfix, from userid 128203) id 604C937054B8; Tue, 1 Sep 2020 19:31:12 -0700 (PDT) From: Yonghong Song To: , CC: Alexei Starovoitov , Daniel Borkmann , , Andrii Nakryiko , Josef Bacik Subject: [PATCH bpf-next v4 1/2] bpf: avoid iterating duplicated files for task_file iterator Date: Tue, 1 Sep 2020 19:31:12 -0700 Message-ID: <20200902023112.1672792-1-yhs@fb.com> X-Mailer: git-send-email 2.24.1 In-Reply-To: <20200902023112.1672735-1-yhs@fb.com> References: <20200902023112.1672735-1-yhs@fb.com> MIME-Version: 1.0 X-FB-Internal: Safe X-Proofpoint-Virus-Version: vendor=fsecure engine=2.50.10434:6.0.235, 18.0.687 definitions=2020-09-02_02:2020-09-01,2020-09-02 signatures=0 X-Proofpoint-Spam-Details: rule=fb_default_notspam policy=fb_default score=0 lowpriorityscore=0 mlxscore=0 suspectscore=8 bulkscore=0 priorityscore=1501 mlxlogscore=999 phishscore=0 adultscore=0 spamscore=0 impostorscore=0 malwarescore=0 clxscore=1015 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2006250000 definitions=main-2009020022 X-FB-Internal: deliver Sender: netdev-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: netdev@vger.kernel.org Currently, task_file iterator iterates all files from all tasks. This may potentially visit a lot of duplicated files if there are many tasks sharing the same files, e.g., typical pthreads where these pthreads and the main thread are sharing the same files. This patch changed task_file iterator to skip a particular task if that task shares the same files as its group_leader (the task having the same tgid and also task->tgid == task->pid). This will preserve the same result, visiting all files from all tasks, and will reduce runtime cost significantl, e.g., if there are a lot of pthreads and the process has a lot of open files. Suggested-by: Andrii Nakryiko Reviewed-by: Josef Bacik Signed-off-by: Yonghong Song --- kernel/bpf/task_iter.c | 15 +++++++++++---- 1 file changed, 11 insertions(+), 4 deletions(-) diff --git a/kernel/bpf/task_iter.c b/kernel/bpf/task_iter.c index 99af4cea1102..5b6af30bfbcd 100644 --- a/kernel/bpf/task_iter.c +++ b/kernel/bpf/task_iter.c @@ -22,7 +22,8 @@ struct bpf_iter_seq_task_info { }; static struct task_struct *task_seq_get_next(struct pid_namespace *ns, - u32 *tid) + u32 *tid, + bool skip_if_dup_files) { struct task_struct *task = NULL; struct pid *pid; @@ -36,6 +37,12 @@ static struct task_struct *task_seq_get_next(struct pid_namespace *ns, if (!task) { ++*tid; goto retry; + } else if (skip_if_dup_files && task->tgid != task->pid && + task->files == task->group_leader->files) { + put_task_struct(task); + task = NULL; + ++*tid; + goto retry; } } rcu_read_unlock(); @@ -48,7 +55,7 @@ static void *task_seq_start(struct seq_file *seq, loff_t *pos) struct bpf_iter_seq_task_info *info = seq->private; struct task_struct *task; - task = task_seq_get_next(info->common.ns, &info->tid); + task = task_seq_get_next(info->common.ns, &info->tid, false); if (!task) return NULL; @@ -65,7 +72,7 @@ static void *task_seq_next(struct seq_file *seq, void *v, loff_t *pos) ++*pos; ++info->tid; put_task_struct((struct task_struct *)v); - task = task_seq_get_next(info->common.ns, &info->tid); + task = task_seq_get_next(info->common.ns, &info->tid, false); if (!task) return NULL; @@ -148,7 +155,7 @@ task_file_seq_get_next(struct bpf_iter_seq_task_file_info *info, curr_files = *fstruct; curr_fd = info->fd; } else { - curr_task = task_seq_get_next(ns, &curr_tid); + curr_task = task_seq_get_next(ns, &curr_tid, true); if (!curr_task) return NULL;