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=-11.7 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI,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 5DD43C433F5 for ; Fri, 3 Sep 2021 11:01:02 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 3CEEA6101A for ; Fri, 3 Sep 2021 11:01:02 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1348442AbhICLCA (ORCPT ); Fri, 3 Sep 2021 07:02:00 -0400 Received: from out30-57.freemail.mail.aliyun.com ([115.124.30.57]:59215 "EHLO out30-57.freemail.mail.aliyun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1348376AbhICLB7 (ORCPT ); Fri, 3 Sep 2021 07:01:59 -0400 X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R551e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e01424;MF=haoxu@linux.alibaba.com;NM=1;PH=DS;RN=4;SR=0;TI=SMTPD_---0Un61DbM_1630666849; Received: from e18g09479.et15sqa.tbsite.net(mailfrom:haoxu@linux.alibaba.com fp:SMTPD_---0Un61DbM_1630666849) by smtp.aliyun-inc.com(127.0.0.1); Fri, 03 Sep 2021 19:00:58 +0800 From: Hao Xu To: Jens Axboe Cc: io-uring@vger.kernel.org, Pavel Begunkov , Joseph Qi Subject: [RFC 0/6] fast poll multishot mode Date: Fri, 3 Sep 2021 19:00:43 +0800 Message-Id: <20210903110049.132958-1-haoxu@linux.alibaba.com> X-Mailer: git-send-email 2.24.4 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org Let multishot support multishot mode, currently only add accept as its first comsumer. theoretical analysis: 1) when connections come in fast - singleshot: add accept sqe(userpsace) --> accept inline ^ | |-----------------| - multishot: add accept sqe(userspace) --> accept inline ^ | |--*--| we do accept repeatedly in * place until get EAGAIN 2) when connections come in at a low pressure similar thing like 1), we reduce a lot of userspace-kernel context switch and useless vfs_poll() tests: Did some tests, which goes in this way: server client(multiple) accept connect read write write read close close Basically, raise up a number of clients(on same machine with server) to connect to the server, and then write some data to it, the server will write those data back to the client after it receives them, and then close the connection after write return. Then the client will read the data and then close the connection. Here I test 10000 clients connect one server, data size 128 bytes. And each client has a go routine for it, so they come to the server in short time. test 20 times before/after this patchset, time spent:(unit cycle, which is the return value of clock()) before: 1930136+1940725+1907981+1947601+1923812+1928226+1911087+1905897+1941075 +1934374+1906614+1912504+1949110+1908790+1909951+1941672+1969525+1934984 +1934226+1914385)/20.0 = 1927633.75 after: 1858905+1917104+1895455+1963963+1892706+1889208+1874175+1904753+1874112 +1874985+1882706+1884642+1864694+1906508+1916150+1924250+1869060+1889506 +1871324+1940803)/20.0 = 1894750.45 (1927633.75 - 1894750.45) / 1927633.75 = 1.65% Higher pressure like 10^5 connections causes problems since ports are in use. I'll test the cancellation path and try to lift pressure to much high level to see if numbers get better. Sent this early for comments and suggestions. Hao Xu (6): io_uring: enhance flush completion logic io_uring: add IORING_ACCEPT_MULTISHOT for accept io_uring: add REQ_F_APOLL_MULTISHOT for requests io_uring: let fast poll support multishot io_uring: implement multishot mode for accept io_uring: enable multishot mode for accept fs/io_uring.c | 72 +++++++++++++++++++++++++++++------ include/uapi/linux/io_uring.h | 4 ++ 2 files changed, 64 insertions(+), 12 deletions(-) -- 2.24.4