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=-8.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE, SPF_PASS,UNPARSEABLE_RELAY,USER_AGENT_SANE_1 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 941E0C43461 for ; Thu, 10 Sep 2020 19:20:39 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 61463206E9 for ; Thu, 10 Sep 2020 19:20:39 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726821AbgIJTUg (ORCPT ); Thu, 10 Sep 2020 15:20:36 -0400 Received: from out30-54.freemail.mail.aliyun.com ([115.124.30.54]:44799 "EHLO out30-54.freemail.mail.aliyun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1731431AbgIJPw2 (ORCPT ); Thu, 10 Sep 2020 11:52:28 -0400 X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R111e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e04395;MF=xiaoguang.wang@linux.alibaba.com;NM=1;PH=DS;RN=4;SR=0;TI=SMTPD_---0U8WQhF._1599753140; Received: from 192.168.124.15(mailfrom:xiaoguang.wang@linux.alibaba.com fp:SMTPD_---0U8WQhF._1599753140) by smtp.aliyun-inc.com(127.0.0.1); Thu, 10 Sep 2020 23:52:20 +0800 Subject: Re: [RFC PATCH for-next] io_uring: support multiple rings to share same poll thread by specifying same cpu To: Jens Axboe , io-uring@vger.kernel.org Cc: asml.silence@gmail.com, joseph.qi@linux.alibaba.com References: <20200910070359.14683-1-xiaoguang.wang@linux.alibaba.com> From: Xiaoguang Wang Message-ID: <6424dacd-7ebb-f8be-ddfa-4e4e96c4a015@linux.alibaba.com> Date: Thu, 10 Sep 2020 23:51:54 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.12.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 7bit Sender: io-uring-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org hi, > On 9/10/20 1:03 AM, Xiaoguang Wang wrote: >> We have already supported multiple rings to share one same poll thread >> by passing IORING_SETUP_ATTACH_WQ, but it's not that convenient to use. >> IORING_SETUP_ATTACH_WQ needs users to ensure that a parent ring instance >> has already existed, that means it will require app to regulate the >> creation oder between uring instances. >> >> Currently we can make this a bit simpler, for those rings which will >> have SQPOLL enabled and are willing to be bound to one same cpu, add a >> capability that these rings can share one poll thread by specifying >> a new IORING_SETUP_SQPOLL_PERCPU flag, then we have 3 cases >> 1, IORING_SETUP_ATTACH_WQ: if user specifies this flag, we'll always >> try to attach this ring to an existing ring's corresponding poll thread, >> no matter whether IORING_SETUP_SQ_AFF or IORING_SETUP_SQPOLL_PERCPU is >> set. >> 2, IORING_SETUP_SQ_AFF and IORING_SETUP_SQPOLL_PERCPU are both enabled, >> for this case, we'll create a single poll thread to be shared by these >> rings, and this poll thread is bound to a fixed cpu. >> 3, for any other cases, we'll just create one new poll thread for the >> corresponding ring. >> >> And for case 2, don't need to regulate creation oder of multiple uring >> instances, we use a mutex to synchronize creation, for example, say five >> rings which all have IORING_SETUP_SQ_AFF & IORING_SETUP_SQPOLL_PERCPU >> enabled, and are willing to be bound same cpu, one ring that gets the >> mutex lock will create one poll thread, the other four rings will just >> attach themselves the previous created poll thread. >> >> To implement above function, add one global hlist_head hash table, only >> sqd that is created for IORING_SETUP_SQ_AFF & IORING_SETUP_SQPOLL_PERCPU >> will be added to this global list, and its search key are current->files >> and cpu number. > > Can you resend this against the current tree? Looks like it's against > something that is outdated. That'll make it easier to test and review. Sorry, I forgot to update my local tree to the current tree. It's a little late today, I'll send a V2 against the current tree tomorrow, thanks. Regards, Xiaoguang Wang >