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=-18.1 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,NICE_REPLY_A,SPF_HELO_NONE,SPF_PASS,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 23EA9C433F5 for ; Sat, 4 Sep 2021 22:40:17 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id E4E9460F5C for ; Sat, 4 Sep 2021 22:40:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233774AbhIDWlS (ORCPT ); Sat, 4 Sep 2021 18:41:18 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:42140 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232111AbhIDWlR (ORCPT ); Sat, 4 Sep 2021 18:41:17 -0400 Received: from mail-wr1-x433.google.com (mail-wr1-x433.google.com [IPv6:2a00:1450:4864:20::433]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 6F8BDC061575 for ; Sat, 4 Sep 2021 15:40:15 -0700 (PDT) Received: by mail-wr1-x433.google.com with SMTP id b10so3974473wru.0 for ; Sat, 04 Sep 2021 15:40:15 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=subject:to:cc:references:from:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=H0cdnyDvgcbniLDDGkPVTtIjL9YZLzFI3MxcKuLxik4=; b=m52MGqssWuyy6ERAQfUoDVQTqawntgG9Gn6zeVNPxR4+hxU4EBASb0FISolo73tNWl DAaYp2E9LU7ISdocoBYDQQnKd/MEsRBDcUx6RebPhNnS1pWUtiuTy380Qy7MwHwwQJye m8KaQNn9rA2biO5F617UDz1+WEjSVxGQExiJA8nFwJGxAu5GF+vB8QfX5r1FvurdUnBL FqlCtQ8k4VD64Grz8waEnxPzaxhCd1bOh/5m1rJyUd+qEH+uWy4Grlpud9ceHd26Jr1b d6yhmiGJoATo6Xd9s6nIJmFy8J6ProkJPKJrYHTh9pDvrMEf2zmFKBPJbeLtXAw+Dkke HKIQ== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:cc:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=H0cdnyDvgcbniLDDGkPVTtIjL9YZLzFI3MxcKuLxik4=; b=UvP1oP54J3eD1J1j1DQ6+kf0erzxxeRdEWVV4Ty5Bq0JLd1NVbBXiyU5nRqwI3HFYp lLH0gKXxWnilBiMB/ZcArMDRnoxvxi1qEEktd8d+jo1nkAFQHbfEzuaHiBCCQp0VKz56 5YoyjzLmyzjt38biw+L4P3ecrhE2DIuA6qZxSxHsyBj6IDczjj+NNRyBb0ZuXHET9Iw5 cJa4E0xYHOJ8O+riVc8qRX4linSvaaTw6o3+UjvDGtkmv0NJqu6tXvmdV71/9xejmZbf tyLo7wLLYhaYB/Hu5lcrfJYXnz+hyuaJO79tgd93iZ3uS0NRkBmwe9EfRZwhd6aoMp9n NraQ== X-Gm-Message-State: AOAM532oH2t37OWWKxhGQUaO9AT1cTRYuuLcVfT3I10NAO28pVdnT2UQ RQ39EQHlf25O2etEPZ/kXLl2xpeulz8= X-Google-Smtp-Source: ABdhPJwnkGfnHem98/xZQubCZOfwWIPHViftF0XHAM67s1FGRkmRkWKxJA5c+1Ok6KmJejd/pFuYqg== X-Received: by 2002:adf:9e01:: with SMTP id u1mr5823647wre.420.1630795213889; Sat, 04 Sep 2021 15:40:13 -0700 (PDT) Received: from [192.168.8.197] ([148.252.133.4]) by smtp.gmail.com with ESMTPSA id a77sm3126680wmd.31.2021.09.04.15.40.12 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sat, 04 Sep 2021 15:40:13 -0700 (PDT) Subject: Re: [PATCH 5/6] io_uring: implement multishot mode for accept To: Hao Xu , Jens Axboe Cc: io-uring@vger.kernel.org, Joseph Qi References: <20210903110049.132958-1-haoxu@linux.alibaba.com> <20210903110049.132958-6-haoxu@linux.alibaba.com> From: Pavel Begunkov Message-ID: <3070a597-3326-5cac-253e-e2b58eebd3a2@gmail.com> Date: Sat, 4 Sep 2021 23:39:40 +0100 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.13.0 MIME-Version: 1.0 In-Reply-To: <20210903110049.132958-6-haoxu@linux.alibaba.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org On 9/3/21 12:00 PM, Hao Xu wrote: > Refactor io_accept() to support multishot mode. Multishot with the fixed/direct mode sounds weird (considering that the slot index is specified by userspace), let's forbid them. io_accept_prep() { if (accept->file_slot && (flags & MULTISHOT)) return -EINVAL; ... } > 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% > > Signed-off-by: Hao Xu > --- > > not sure if we should cancel it when io_cqring_fill_event() reurn false > > fs/io_uring.c | 34 +++++++++++++++++++++++++++++----- > 1 file changed, 29 insertions(+), 5 deletions(-) > > diff --git a/fs/io_uring.c b/fs/io_uring.c > index dae7044e0c24..eb81d37dce78 100644 > --- a/fs/io_uring.c > +++ b/fs/io_uring.c > @@ -4885,16 +4885,18 @@ static int io_accept_prep(struct io_kiocb *req, const struct io_uring_sqe *sqe) > > static int io_accept(struct io_kiocb *req, unsigned int issue_flags) > { > + struct io_ring_ctx *ctx = req->ctx; > struct io_accept *accept = &req->accept; > bool force_nonblock = issue_flags & IO_URING_F_NONBLOCK; > unsigned int file_flags = force_nonblock ? O_NONBLOCK : 0; > bool fixed = !!accept->file_slot; > struct file *file; > - int ret, fd; > + int ret, ret2 = 0, fd; > > if (req->file->f_flags & O_NONBLOCK) > req->flags |= REQ_F_NOWAIT; > > +retry: > if (!fixed) { > fd = __get_unused_fd_flags(accept->flags, accept->nofile); > if (unlikely(fd < 0)) > @@ -4906,20 +4908,42 @@ static int io_accept(struct io_kiocb *req, unsigned int issue_flags) > if (!fixed) > put_unused_fd(fd); > ret = PTR_ERR(file); > - if (ret == -EAGAIN && force_nonblock) > - return -EAGAIN; > + if (ret == -EAGAIN && force_nonblock) { > + if ((req->flags & (REQ_F_APOLL_MULTISHOT | REQ_F_POLLED)) == > + (REQ_F_APOLL_MULTISHOT | REQ_F_POLLED)) > + ret = 0; > + return ret; > + } > if (ret == -ERESTARTSYS) > ret = -EINTR; > req_set_fail(req); > } else if (!fixed) { > fd_install(fd, file); > ret = fd; > + /* > + * if it's in multishot mode, let's return -EAGAIN to make it go > + * into fast poll path > + */ > + if ((req->flags & REQ_F_APOLL_MULTISHOT) && force_nonblock && > + !(req->flags & REQ_F_POLLED)) > + ret2 = -EAGAIN; > } else { > ret = io_install_fixed_file(req, file, issue_flags, > accept->file_slot - 1); > } > - __io_req_complete(req, issue_flags, ret, 0); > - return 0; > + > + if (req->flags & REQ_F_APOLL_MULTISHOT) { > + spin_lock(&ctx->completion_lock); > + if (io_cqring_fill_event(ctx, req->user_data, ret, 0)) { > + io_commit_cqring(ctx); > + ctx->cq_extra++; > + } > + spin_unlock(&ctx->completion_lock); > + goto retry; > + } else { > + __io_req_complete(req, issue_flags, ret, 0); > + } > + return ret2; > } > > static int io_connect_prep_async(struct io_kiocb *req) > -- Pavel Begunkov