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=-9.7 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, UNPARSEABLE_RELAY,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 2B9E3C433E1 for ; Fri, 12 Jun 2020 02:30:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1674520835 for ; Fri, 12 Jun 2020 02:30:25 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726386AbgFLCaY (ORCPT ); Thu, 11 Jun 2020 22:30:24 -0400 Received: from out30-44.freemail.mail.aliyun.com ([115.124.30.44]:58790 "EHLO out30-44.freemail.mail.aliyun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726326AbgFLCaY (ORCPT ); Thu, 11 Jun 2020 22:30:24 -0400 X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R171e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e01422;MF=jiufei.xue@linux.alibaba.com;NM=1;PH=DS;RN=3;SR=0;TI=SMTPD_---0U.K0ya1_1591929020; Received: from localhost(mailfrom:jiufei.xue@linux.alibaba.com fp:SMTPD_---0U.K0ya1_1591929020) by smtp.aliyun-inc.com(127.0.0.1); Fri, 12 Jun 2020 10:30:21 +0800 From: Jiufei Xue To: io-uring@vger.kernel.org Cc: axboe@kernel.dk, joseph.qi@linux.alibaba.com Subject: [PATCH v3 2/2] io_uring: use EPOLLEXCLUSIVE flag to aoid thundering herd type behavior Date: Fri, 12 Jun 2020 10:30:18 +0800 Message-Id: <1591929018-73954-3-git-send-email-jiufei.xue@linux.alibaba.com> X-Mailer: git-send-email 1.8.3.1 In-Reply-To: <1591929018-73954-1-git-send-email-jiufei.xue@linux.alibaba.com> References: <1591929018-73954-1-git-send-email-jiufei.xue@linux.alibaba.com> Sender: io-uring-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org Applications can pass this flag in to avoid accept thundering herd. Signed-off-by: Jiufei Xue --- fs/io_uring.c | 9 +++++++-- 1 file changed, 7 insertions(+), 2 deletions(-) diff --git a/fs/io_uring.c b/fs/io_uring.c index 6250227..03951ec 100644 --- a/fs/io_uring.c +++ b/fs/io_uring.c @@ -4289,7 +4289,11 @@ static void __io_queue_proc(struct io_poll_iocb *poll, struct io_poll_table *pt, pt->error = 0; poll->head = head; - add_wait_queue(head, &poll->wait); + + if (poll->events & EPOLLEXCLUSIVE) + add_wait_queue_exclusive(head, &poll->wait); + else + add_wait_queue(head, &poll->wait); } static void io_async_queue_proc(struct file *file, struct wait_queue_head *head, @@ -4612,7 +4616,8 @@ static int io_poll_add_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe return -EBADF; events = READ_ONCE(sqe->poll_events); - poll->events = demangle_poll(events) | EPOLLERR | EPOLLHUP; + poll->events = demangle_poll(events) | EPOLLERR | EPOLLHUP | + (events & EPOLLEXCLUSIVE); get_task_struct(current); req->task = current; -- 1.8.3.1