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=-4.8 required=3.0 tests=DKIM_ADSP_CUSTOM_MED, DKIM_INVALID,DKIM_SIGNED,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE, SPF_PASS,USER_AGENT_SANE_1 autolearn=no 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 E5A4CC433DF for ; Mon, 25 May 2020 07:30:43 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id A259D2065F for ; Mon, 25 May 2020 07:30:43 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="GsE5BPXq" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org A259D2065F Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=gmail.com Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 2F2628001F; Mon, 25 May 2020 03:30:43 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 2A3588000E; Mon, 25 May 2020 03:30:43 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 143D38001F; Mon, 25 May 2020 03:30:43 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0022.hostedemail.com [216.40.44.22]) by kanga.kvack.org (Postfix) with ESMTP id EA7C88000E for ; Mon, 25 May 2020 03:30:42 -0400 (EDT) Received: from smtpin13.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id B29743D01 for ; Mon, 25 May 2020 07:30:42 +0000 (UTC) X-FDA: 76854419124.13.light00_7a9139af75429 X-HE-Tag: light00_7a9139af75429 X-Filterd-Recvd-Size: 8674 Received: from mail-ej1-f65.google.com (mail-ej1-f65.google.com [209.85.218.65]) by imf07.hostedemail.com (Postfix) with ESMTP for ; Mon, 25 May 2020 07:30:42 +0000 (UTC) Received: by mail-ej1-f65.google.com with SMTP id j21so19510368ejy.1 for ; Mon, 25 May 2020 00:30:42 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=to:cc:references:from:autocrypt:subject:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=5rfonPZQAU0x3lqMl+lkcXTi06d4c3g+/vgihQ8n1yk=; b=GsE5BPXqZHk5g2bIv7atz9cFunL+ERjc8DEd5zHUnRVF/WbDpO+y9I9tPHioCQU7lu mPBaxLN7wDMHZ/p00Ge6cUxPD3+kSSQ8Pkl7CVF5pW2JR+DVMqkw1qzpf86+DO9IsVYO 2T8wazCGInUu2ltwdemVS99UXquRXV1o0hSxAGRn/BVbhZ60HHaqIkhMp5o1rAKrG/0M k11GGA6U7v35eYX1zPSYQmjr/iVGPzbQKg/1qDdyCfi45y63theB8vCvCx8LL4/cxKcC Wq3vPKmkNbtZDDfMG2c3M5G0Z/az7lAeci9fe3eWEAYyA0qz4qNQ5z9BZ0A8PZYCmXXl bSlA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:to:cc:references:from:autocrypt:subject :message-id:date:user-agent:mime-version:in-reply-to :content-language:content-transfer-encoding; bh=5rfonPZQAU0x3lqMl+lkcXTi06d4c3g+/vgihQ8n1yk=; b=Or4ihPhl2R6RZlNsMd5Dhx5vgIWnpK6+j+GiqtQ4MpgLvIWLW7/taYaJlLz2hpiK4P 0DbyLYV5FaY0Tew6B6GYxu7Oq6ESZra4VUR6kjFvl86pCOjy1a16OYCIp2V2ufHVPhWG 7uq1Gr2uMVIdOQalBBw1bifcDcTBp/M6Tic50m5Gf4ReHNBXkheZIUJsxsClpt2RBpv0 m+fgBcRzdvur37KDuLSStKvZzbEbexuLchYdkxIQJ4Zvta1QSGPc5d8EP/CA7pgpsfE+ W9lI5JYdGcvFFhwT4i9cD+UmP9D3rSzGZeCwIeUhjLvDF8ysc8b1J7w9FLj0z/4w5DG1 3Ikw== X-Gm-Message-State: AOAM532QA0eOe8jjL/qiJkSc2Nw9s1AXrqPV2aYlsjpCnFPLYifpdPRW JJ61/Uygds9pp94uuHErrbcno1Iu X-Google-Smtp-Source: ABdhPJwQG0i2iSkYkGK5TtEeu4oyrWWXUm6C79+dCl1PI+StIwF2kmfIaKdd41djbQ6Tg0qjmXQ8Kw== X-Received: by 2002:a17:906:3d69:: with SMTP id r9mr17067535ejf.20.1590391840736; Mon, 25 May 2020 00:30:40 -0700 (PDT) Received: from [192.168.43.221] ([46.191.65.149]) by smtp.gmail.com with ESMTPSA id 25sm14622608ejy.32.2020.05.25.00.30.39 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 25 May 2020 00:30:40 -0700 (PDT) To: Jens Axboe , io-uring@vger.kernel.org Cc: linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org References: <20200523185755.8494-1-axboe@kernel.dk> <20200523185755.8494-13-axboe@kernel.dk> From: Pavel Begunkov Autocrypt: addr=asml.silence@gmail.com; prefer-encrypt=mutual; keydata= mQINBFmKBOQBEAC76ZFxLAKpDw0bKQ8CEiYJRGn8MHTUhURL02/7n1t0HkKQx2K1fCXClbps bdwSHrhOWdW61pmfMbDYbTj6ZvGRvhoLWfGkzujB2wjNcbNTXIoOzJEGISHaPf6E2IQx1ik9 6uqVkK1OMb7qRvKH0i7HYP4WJzYbEWVyLiAxUj611mC9tgd73oqZ2pLYzGTqF2j6a/obaqha +hXuWTvpDQXqcOZJXIW43atprH03G1tQs7VwR21Q1eq6Yvy2ESLdc38EqCszBfQRMmKy+cfp W3U9Mb1w0L680pXrONcnlDBCN7/sghGeMHjGKfNANjPc+0hzz3rApPxpoE7HC1uRiwC4et83 CKnncH1l7zgeBT9Oa3qEiBlaa1ZCBqrA4dY+z5fWJYjMpwI1SNp37RtF8fKXbKQg+JuUjAa9 Y6oXeyEvDHMyJYMcinl6xCqCBAXPHnHmawkMMgjr3BBRzODmMr+CPVvnYe7BFYfoajzqzq+h EyXSl3aBf0IDPTqSUrhbmjj5OEOYgRW5p+mdYtY1cXeK8copmd+fd/eTkghok5li58AojCba jRjp7zVOLOjDlpxxiKhuFmpV4yWNh5JJaTbwCRSd04sCcDNlJj+TehTr+o1QiORzc2t+N5iJ NbILft19Izdn8U39T5oWiynqa1qCLgbuFtnYx1HlUq/HvAm+kwARAQABtDFQYXZlbCBCZWd1 bmtvdiAoc2lsZW5jZSkgPGFzbWwuc2lsZW5jZUBnbWFpbC5jb20+iQJOBBMBCAA4FiEE+6Ju PTjTbx479o3OWt5b1Glr+6UFAlmKBOQCGwMFCwkIBwIGFQgJCgsCBBYCAwECHgECF4AACgkQ Wt5b1Glr+6WxZA//QueaKHzgdnOikJ7NA/Vq8FmhRlwgtP0+E+w93kL+ZGLzS/cUCIjn2f4Q Mcutj2Neg0CcYPX3b2nJiKr5Vn0rjJ/suiaOa1h1KzyNTOmxnsqE5fmxOf6C6x+NKE18I5Jy xzLQoktbdDVA7JfB1itt6iWSNoOTVcvFyvfe5ggy6FSCcP+m1RlR58XxVLH+qlAvxxOeEr/e aQfUzrs7gqdSd9zQGEZo0jtuBiB7k98t9y0oC9Jz0PJdvaj1NZUgtXG9pEtww3LdeXP/TkFl HBSxVflzeoFaj4UAuy8+uve7ya/ECNCc8kk0VYaEjoVrzJcYdKP583iRhOLlZA6HEmn/+Gh9 4orG67HNiJlbFiW3whxGizWsrtFNLsSP1YrEReYk9j1SoUHHzsu+ZtNfKuHIhK0sU07G1OPN 2rDLlzUWR9Jc22INAkhVHOogOcc5ajMGhgWcBJMLCoi219HlX69LIDu3Y34uIg9QPZIC2jwr 24W0kxmK6avJr7+n4o8m6sOJvhlumSp5TSNhRiKvAHB1I2JB8Q1yZCIPzx+w1ALxuoWiCdwV M/azguU42R17IuBzK0S3hPjXpEi2sK/k4pEPnHVUv9Cu09HCNnd6BRfFGjo8M9kZvw360gC1 reeMdqGjwQ68o9x0R7NBRrtUOh48TDLXCANAg97wjPoy37dQE7e5Ag0EWYoE5AEQAMWS+aBV IJtCjwtfCOV98NamFpDEjBMrCAfLm7wZlmXy5I6o7nzzCxEw06P2rhzp1hIqkaab1kHySU7g dkpjmQ7Jjlrf6KdMP87mC/Hx4+zgVCkTQCKkIxNE76Ff3O9uTvkWCspSh9J0qPYyCaVta2D1 Sq5HZ8WFcap71iVO1f2/FEHKJNz/YTSOS/W7dxJdXl2eoj3gYX2UZNfoaVv8OXKaWslZlgqN jSg9wsTv1K73AnQKt4fFhscN9YFxhtgD/SQuOldE5Ws4UlJoaFX/yCoJL3ky2kC0WFngzwRF Yo6u/KON/o28yyP+alYRMBrN0Dm60FuVSIFafSqXoJTIjSZ6olbEoT0u17Rag8BxnxryMrgR dkccq272MaSS0eOC9K2rtvxzddohRFPcy/8bkX+t2iukTDz75KSTKO+chce62Xxdg62dpkZX xK+HeDCZ7gRNZvAbDETr6XI63hPKi891GeZqvqQVYR8e+V2725w+H1iv3THiB1tx4L2bXZDI DtMKQ5D2RvCHNdPNcZeldEoJwKoA60yg6tuUquvsLvfCwtrmVI2rL2djYxRfGNmFMrUDN1Xq F3xozA91q3iZd9OYi9G+M/OA01husBdcIzj1hu0aL+MGg4Gqk6XwjoSxVd4YT41kTU7Kk+/I 5/Nf+i88ULt6HanBYcY/+Daeo/XFABEBAAGJAjYEGAEIACAWIQT7om49ONNvHjv2jc5a3lvU aWv7pQUCWYoE5AIbDAAKCRBa3lvUaWv7pfmcEACKTRQ28b1y5ztKuLdLr79+T+LwZKHjX++P 4wKjEOECCcB6KCv3hP+J2GCXDOPZvdg/ZYZafqP68Yy8AZqkfa4qPYHmIdpODtRzZSL48kM8 LRzV8Rl7J3ItvzdBRxf4T/Zseu5U6ELiQdCUkPGsJcPIJkgPjO2ROG/ZtYa9DvnShNWPlp+R uPwPccEQPWO/NP4fJl2zwC6byjljZhW5kxYswGMLBwb5cDUZAisIukyAa8Xshdan6C2RZcNs rB3L7vsg/R8UCehxOH0C+NypG2GqjVejNZsc7bgV49EOVltS+GmGyY+moIzxsuLmT93rqyII 5rSbbcTLe6KBYcs24XEoo49Zm9oDA3jYvNpeYD8rDcnNbuZh9kTgBwFN41JHOPv0W2FEEWqe JsCwQdcOQ56rtezdCJUYmRAt3BsfjN3Jn3N6rpodi4Dkdli8HylM5iq4ooeb5VkQ7UZxbCWt UVMKkOCdFhutRmYp0mbv2e87IK4erwNHQRkHUkzbsuym8RVpAZbLzLPIYK/J3RTErL6Z99N2 m3J6pjwSJY/zNwuFPs9zGEnRO4g0BUbwGdbuvDzaq6/3OJLKohr5eLXNU3JkT+3HezydWm3W OPhauth7W0db74Qd49HXK0xe/aPrK+Cp+kU1HRactyNtF8jZQbhMCC8vMGukZtWaAwpjWiiH bA== Subject: Re: [PATCH 12/12] io_uring: support true async buffered reads, if file provides it Message-ID: <8d429d6b-81ee-0a28-8533-2e1d4faa6b37@gmail.com> Date: Mon, 25 May 2020 10:29:25 +0300 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.3.0 MIME-Version: 1.0 In-Reply-To: <20200523185755.8494-13-axboe@kernel.dk> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: quoted-printable X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 23/05/2020 21:57, Jens Axboe wrote: > If the file is flagged with FMODE_BUF_RASYNC, then we don't have to pun= t > the buffered read to an io-wq worker. Instead we can rely on page > unlocking callbacks to support retry based async IO. This is a lot more > efficient than doing async thread offload. >=20 > The retry is done similarly to how we handle poll based retry. From > the unlock callback, we simply queue the retry to a task_work based > handler. >=20 > Signed-off-by: Jens Axboe > --- > fs/io_uring.c | 99 +++++++++++++++++++++++++++++++++++++++++++++++++++ > 1 file changed, 99 insertions(+) >=20 ... > + > + init_task_work(&rw->task_work, io_async_buf_retry); > + /* submit ref gets dropped, acquire a new one */ > + refcount_inc(&req->refs); > + tsk =3D req->task; > + ret =3D task_work_add(tsk, &rw->task_work, true); > + if (unlikely(ret)) { > + /* queue just for cancelation */ > + init_task_work(&rw->task_work, io_async_buf_cancel); > + tsk =3D io_wq_get_task(req->ctx->io_wq); IIRC, task will be put somewhere around io_free_req(). Then shouldn't her= e be some juggling with reassigning req->task with task_{get,put}()? > + task_work_add(tsk, &rw->task_work, true); > + } > + wake_up_process(tsk); > + return 1; > +} ... > static int io_read(struct io_kiocb *req, bool force_nonblock) > { > struct iovec inline_vecs[UIO_FASTIOV], *iovec =3D inline_vecs; > @@ -2601,6 +2696,7 @@ static int io_read(struct io_kiocb *req, bool for= ce_nonblock) > if (!ret) { > ssize_t ret2; > =20 > +retry: > if (req->file->f_op->read_iter) > ret2 =3D call_read_iter(req->file, kiocb, &iter); > else > @@ -2619,6 +2715,9 @@ static int io_read(struct io_kiocb *req, bool for= ce_nonblock) > if (!(req->flags & REQ_F_NOWAIT) && > !file_can_poll(req->file)) > req->flags |=3D REQ_F_MUST_PUNT; > + if (io_rw_should_retry(req)) It looks like a state machine with IOCB_WAITQ and gotos. Wouldn't it be c= leaner to call call_read_iter()/loop_rw_iter() here directly instead of "goto re= try" ? BTW, can this async stuff return -EAGAIN ? > + goto retry; > + kiocb->ki_flags &=3D ~IOCB_WAITQ; > return -EAGAIN; > } > } >=20 --=20 Pavel Begunkov