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=-7.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,MENTIONS_GIT_HOSTING, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,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 ED5B4C2BA83 for ; Thu, 13 Feb 2020 15:08:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id AF42420873 for ; Thu, 13 Feb 2020 15:08:13 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="TZL5c2yT" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727347AbgBMPIN (ORCPT ); Thu, 13 Feb 2020 10:08:13 -0500 Received: from mail-lj1-f175.google.com ([209.85.208.175]:33575 "EHLO mail-lj1-f175.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726937AbgBMPIN (ORCPT ); Thu, 13 Feb 2020 10:08:13 -0500 Received: by mail-lj1-f175.google.com with SMTP id y6so7003382lji.0 for ; Thu, 13 Feb 2020 07:08:09 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=subject:to:cc:references:from:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=sERHr2/Up3vmok5oE9m78EPT9j+qjhaMneIVOseolQk=; b=TZL5c2yTj/kzbJz9/6wc6vGHI1m2PpBp/PYzXPoNHSI1tutS/9BdMayAGMD9lQQ/QL ojeCurgF2H8Po7hGr3ZKRqbhakTYCjkKDGoAxchc1FexgBLGUykmgxKIdSltDhzmjeE4 AxK3E64I10CbDNw4vivLZTS6DyGAQYHrclEr4OjX6iT4Jvfc0+lTMNiR811wfb+qd7Mg yUA88KqKcWzJOuNq5/uFNgttsX63KBS+m2JNr25ctL5uX7VAP9eOgWFIgLgVVealeV/Q VYRANSn41pwFoNpLiNSE8ycVJ+6o3Bj6wwnONGoPCvZqBxQ1vqTBjFvBBfFU8jqhgreQ Fn/A== 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=sERHr2/Up3vmok5oE9m78EPT9j+qjhaMneIVOseolQk=; b=Khghd1qlhFFEaC7TnUV2E/FQBUO6p3lSwNLPKwm5HPo5ovFIdcH35+JEYxRNliHqXM 6bu0zEnw/DIKVg+l1vii6DtmGznw7Gx838DzDPKsTqgxsN+6JyeS8Zh8C5uelV40/tlL T2JWyFJ4Du+B1wtVTVZfyqA1vDGc67w7VbsZG1OJKBUQIHKVfv/avosaa8pnfa8PTKdW lQR54Kxcj+zgicbPwtPe6MvWujnVgQ/FEZ/2jBJDacwEJqKDj8+CvUez+ss90+vpORay /3IMC7zfmbrDp6/OCXsI/0idf5pvyBXbcv8jj4vBU6v8tgEFiLYhd+KhaBt0q8lBhgRN BYjw== X-Gm-Message-State: APjAAAXt6vZlEHNFiw/9MlYV1nuADWwfDaJprIne5HhaI2SNwXDTlkwa SptnPFghbZyiV0frGyY0wQdUIsnU X-Google-Smtp-Source: APXvYqwAWEwQGwMaBGxTDG+ajG8N732M5RlOFAOKFjAG/WNBsm8ZjoSJBNpHaBWl+KYqHWGCnLh/mQ== X-Received: by 2002:a05:651c:120d:: with SMTP id i13mr11353332lja.173.1581606487846; Thu, 13 Feb 2020 07:08:07 -0800 (PST) Received: from [172.31.190.83] ([86.57.146.226]) by smtp.gmail.com with ESMTPSA id m3sm1403678lfl.97.2020.02.13.07.08.06 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Thu, 13 Feb 2020 07:08:07 -0800 (PST) Subject: Re: [ISSUE] The time cost of IOSQE_IO_LINK To: =?UTF-8?B?Q2FydGVyIExpIOadjumAmua0sg==?= , Jens Axboe Cc: io-uring References: <9FEF0D34-A012-4505-AA4E-FF97CC302A33@eoitek.com> <8a3ee653-77ed-105d-c1c3-87087451914e@kernel.dk> From: Pavel Begunkov Message-ID: <9a8e4c8a-f8b2-900d-92b6-cc69b6adf324@gmail.com> Date: Thu, 13 Feb 2020 18:08:05 +0300 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.4.2 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: io-uring-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org On 2/13/2020 3:33 AM, Carter Li 李通洲 wrote: > Thanks for your reply. > > You are right the nop isn't really a good test case. But I actually > found this issue when benchmarking my echo server, which didn't use > NOP of course. If there are no hidden subtle issues in io_uring, your benchmark or the used pattern itself, it's probably because of overhead on async punting (copying iovecs, several extra switches, refcounts, grabbing mm/fs/etc, io-wq itself). I was going to tune async/punting stuff anyway, so I'll look into this. And of course, there is always a good chance Jens have some bright insights BTW, what's benefit of doing poll(fd)->read(fd), but not directly read()? > Test case attached below. Use rust_echo_bench for benchmarking. > https://github.com/haraldh/rust_echo_bench > > > $ gcc link_recv.c -o link_recv -luring -O3 -DUSE_LINK=0 > $ ./link_recv 12345 > $ cargo run --release # On another console > Benchmarking: 127.0.0.1:12345 > 50 clients, running 512 bytes, 60 sec. > > Speed: 168264 request/sec, 168264 response/sec > Requests: 10095846 > Responses: 10095844 > > $ gcc link_recv.c -o link_recv -luring -O3 -DUSE_LINK=1 > $ ./link_recv 12345 > $ cargo run --release # On another console > Benchmarking: 127.0.0.1:12345 > 50 clients, running 512 bytes, 60 sec. > > Speed: 112666 request/sec, 112666 response/sec > Requests: 6760009 > Responses: 6759975 > > > I think `POLL_ADD(POLLIN)-RECV` and `POLL_ADD(POLLOUT)-SEND` are common use cases for networking ( for some reason a short read for SEND is not considered an error, `RECV-SEND` cannot be used in a link chain ). RECV/SEND won't block after polled. I expect better performance for fewer io_uring_enter syscalls. Could you please have a check with it? > > Another more complex test case `POLL_ADD-READ_FIXED-WRITE_FIXED` I have posted on Github, which currently results in freeze. > > https://github.com/axboe/liburing/issues/71 > > Carter > > --- > > #include > #include > #include > #include > > #include > #include > #include > > #include > > #define BACKLOG 128 > #define MAX_MESSAGE_LEN 1024 > #define MAX_CONNECTIONS 1024 > #ifndef USE_LINK > # define USE_LINK 0 > #endif > > enum { ACCEPT, POLL, READ, WRITE }; > > struct conn_info { > __u32 fd; > __u32 type; > }; > > typedef char buf_type[MAX_CONNECTIONS][MAX_MESSAGE_LEN]; > > static struct io_uring ring; > static unsigned cqe_count = 0; > > int init_socket(int portno) { > int sock_listen_fd = socket(AF_INET, SOCK_STREAM, 0); > if (sock_listen_fd < 0) { > perror("socket"); > return -1; > } > > struct sockaddr_in server_addr = { > .sin_family = AF_INET, > .sin_port = htons(portno), > .sin_addr = { > .s_addr = INADDR_ANY, > }, > }; > > if (bind(sock_listen_fd, (struct sockaddr *)&server_addr, sizeof(server_addr)) < 0) { > perror("bind"); > return -1; > } > > if (listen(sock_listen_fd, BACKLOG) < 0) { > perror("listen"); > return -1; > } > > return sock_listen_fd; > } > > static struct io_uring_sqe* get_sqe_safe() { > struct io_uring_sqe *sqe = io_uring_get_sqe(&ring); > if (__builtin_expect(!!sqe, 1)) { > return sqe; > } else { > io_uring_cq_advance(&ring, cqe_count); > cqe_count = 0; > io_uring_submit(&ring); > return io_uring_get_sqe(&ring); > } > } > > static void add_accept(int fd, struct sockaddr *client_addr, socklen_t *client_len) { > struct io_uring_sqe *sqe = get_sqe_safe(); > struct conn_info conn_i = { > .fd = fd, > .type = ACCEPT, > }; > > io_uring_prep_accept(sqe, fd, client_addr, client_len, 0); > memcpy(&sqe->user_data, &conn_i, sizeof(conn_i)); > } > > static void add_poll(int fd, int poll_mask, unsigned flags) { > struct io_uring_sqe *sqe = get_sqe_safe(); > struct conn_info conn_i = { > .fd = fd, > .type = POLL, > }; > > io_uring_prep_poll_add(sqe, fd, poll_mask); > io_uring_sqe_set_flags(sqe, flags); > memcpy(&sqe->user_data, &conn_i, sizeof(conn_i)); > } > > static void add_socket_read(int fd, size_t size, buf_type *bufs) { > struct io_uring_sqe *sqe = get_sqe_safe(); > struct conn_info conn_i = { > .fd = fd, > .type = READ, > }; > > io_uring_prep_recv(sqe, fd, (*bufs)[fd], size, MSG_NOSIGNAL); > memcpy(&sqe->user_data, &conn_i, sizeof(conn_i)); > } > > static void add_socket_write(int fd, size_t size, buf_type *bufs, unsigned flags) { > struct io_uring_sqe *sqe = get_sqe_safe(); > struct conn_info conn_i = { > .fd = fd, > .type = WRITE, > }; > > io_uring_prep_send(sqe, fd, (*bufs)[fd], size, MSG_NOSIGNAL); > io_uring_sqe_set_flags(sqe, flags); > memcpy(&sqe->user_data, &conn_i, sizeof(conn_i)); > } > > int main(int argc, char *argv[]) { > if (argc < 2) { > fprintf(stderr, "Please give a port number: %s [port]\n", argv[0]); > return 1; > } > > int portno = strtol(argv[1], NULL, 10); > int sock_listen_fd = init_socket(portno); > if (sock_listen_fd < 0) return -1; > printf("io_uring echo server listening for connections on port: %d\n", portno); > > > int ret = io_uring_queue_init(BACKLOG, &ring, 0); > if (ret < 0) { > fprintf(stderr, "queue_init: %s\n", strerror(-ret)); > return -1; > } > > buf_type *bufs = (buf_type *)malloc(sizeof(*bufs)); > > struct sockaddr_in client_addr; > socklen_t client_len = sizeof(client_addr); > add_accept(sock_listen_fd, (struct sockaddr *)&client_addr, &client_len); > > while (1) { > io_uring_submit_and_wait(&ring, 1); > > struct io_uring_cqe *cqe; > unsigned head; > > io_uring_for_each_cqe(&ring, head, cqe) { > ++cqe_count; > > struct conn_info conn_i; > memcpy(&conn_i, &cqe->user_data, sizeof(conn_i)); > int result = cqe->res; > > switch (conn_i.type) { > case ACCEPT: > #if USE_LINK > add_poll(result, POLLIN, IOSQE_IO_LINK); > add_socket_read(result, MAX_MESSAGE_LEN, bufs); > #else > add_poll(result, POLLIN, 0); > #endif > add_accept(sock_listen_fd, (struct sockaddr *)&client_addr, &client_len); > break; > > #if !USE_LINK > case POLL: > add_socket_read(conn_i.fd, MAX_MESSAGE_LEN, bufs); > break; > #endif > > case READ: > if (__builtin_expect(result <= 0, 0)) { > shutdown(conn_i.fd, SHUT_RDWR); > } else { > add_socket_write(conn_i.fd, result, bufs, 0); > } > break; > > case WRITE: > #if USE_LINK > add_poll(conn_i.fd, POLLIN, IOSQE_IO_LINK); > add_socket_read(conn_i.fd, MAX_MESSAGE_LEN, bufs); > #else > add_poll(conn_i.fd, POLLIN, 0); > #endif > break; > } > } > > io_uring_cq_advance(&ring, cqe_count); > cqe_count = 0; > } > > > close(sock_listen_fd); > free(bufs); > } > > > >> 2020年2月13日 上午1:11，Jens Axboe 写道： >> >> On 2/12/20 9:31 AM, Carter Li 李通洲 wrote: >>> Hi everyone, >>> >>> IOSQE_IO_LINK seems to have very high cost, even greater then io_uring_enter syscall. >>> >>> Test code attached below. The program completes after getting 100000000 cqes. >>> >>> $ gcc test.c -luring -o test0 -g -O3 -DUSE_LINK=0 >>> $ time ./test0 >>> USE_LINK: 0, count: 100000000, submit_count: 1562500 >>> 0.99user 9.99system 0:11.02elapsed 99%CPU (0avgtext+0avgdata 1608maxresident)k >>> 0inputs+0outputs (0major+72minor)pagefaults 0swaps >>> >>> $ gcc test.c -luring -o test1 -g -O3 -DUSE_LINK=1 >>> $ time ./test1 >>> USE_LINK: 1, count: 100000110, submit_count: 799584 >>> 0.83user 19.21system 0:20.90elapsed 95%CPU (0avgtext+0avgdata 1632maxresident)k >>> 0inputs+0outputs (0major+72minor)pagefaults 0swaps >>> >>> As you can see, the `-DUSE_LINK=1` version emits only about half io_uring_submit calls >>> of the other version, but takes twice as long. That makes IOSQE_IO_LINK almost useless, >>> please have a check. >> >> The nop isn't really a good test case, as it doesn't contain any smarts >> in terms of executing a link fast. So it doesn't say a whole lot outside >> of "we could make nop links faster", which is also kind of pointless. >> >> "Normal" commands will work better. Where the link is really a win is if >> the first request needs to go async to complete. For that case, the >> next link can execute directly from that context. This saves an async >> punt for the common case. >> >> -- >> Jens Axboe >> > -- Pavel Begunkov