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=-5.6 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,NICE_REPLY_A,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 BDE64C433E2 for ; Mon, 13 Jul 2020 08:19:25 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 837402072D for ; Mon, 13 Jul 2020 08:19:25 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="tmD2NH9V" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726523AbgGMITZ (ORCPT ); Mon, 13 Jul 2020 04:19:25 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55488 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725818AbgGMITY (ORCPT ); Mon, 13 Jul 2020 04:19:24 -0400 Received: from mail-ej1-x636.google.com (mail-ej1-x636.google.com [IPv6:2a00:1450:4864:20::636]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 988E1C061755 for ; Mon, 13 Jul 2020 01:19:24 -0700 (PDT) Received: by mail-ej1-x636.google.com with SMTP id ga4so15474004ejb.11 for ; Mon, 13 Jul 2020 01:19:24 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=to:references:from:autocrypt:subject:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=FBC6tnEKKXyThx6a9eVIgSnRN3wb13o5O8Ym1EQ5vuE=; b=tmD2NH9VwA4jmEMh4A1MkwY0PLdTrwJgXaYB1y7xYdxL1CLECsx/XQAiThXjv+fkCr iNhG42S2igFzlMPVluL+4QUHbOYZl8D3Ek9IWkiY3hHhy7RQhYCiBs8s6vBOImHSQ+AA H9KDmkU66173F+lpoWCkpAz2Zt63xYITAyfKM5XJMOVNxIu1nqat5hnGQDTjuFxdqB5w OFt7bYXBO959LfGNyAlsgDVxW2jNgd9ahYfPIE2zQWI78K3xH4B1Q2SZkMy2TftWJ8Yk MyJmEFE2Ot8lSshBhWwrWXdaDDAxkKNZhCeWdezuF1e1EmozSulJ9hfKCLHbAnqx18SF eCZA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:to:references:from:autocrypt:subject:message-id :date:user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=FBC6tnEKKXyThx6a9eVIgSnRN3wb13o5O8Ym1EQ5vuE=; b=Z6phN7ZLvviIMoEvWnuM9E8s3wk/JEm87owO7e42QBK36xjmLW/PkGune6t2FUFe/F DBsJJMnL8ZdZ12SrLshUXgrY7RGDIKkS3+nSdd7VzUS2brM02dHEX5PeyZyR0Np7i+TI CGulcjMdZ5jgTdoitqOBj9qDhsn/g/O1WMwtAASVQhWojsd1dED4F8TVtimZzw1dUaRs nIFnrw5Yh947c9CdRDe4X19L8e0n/sDkMNGUo3mfbPbMyOwjztyl82XXr8fH8+0lO3hB AzVHzg/oSIc8TjB793Boj74d5FxjuwDTsrhTD1b3Q6eS++gftqZxJ/PtPG4k8XsWCmOo OKSQ== X-Gm-Message-State: AOAM531kTHLr1S09Q5QffdkoSbcn/lYnCitJ+XMrchdFNRiyBYbyo0Ax nB2gdnYlynPTQqeF6CXzo/uiXnVU X-Google-Smtp-Source: ABdhPJwTxe4jPifnTA8DA/5SKiYGUkj1ZIsdWZ9HmVzvADJNKdC1oLTIsr70n0LIVK8/3wFiyNGmCA== X-Received: by 2002:a17:906:7247:: with SMTP id n7mr72816825ejk.105.1594628362917; Mon, 13 Jul 2020 01:19:22 -0700 (PDT) Received: from [192.168.43.17] ([5.100.193.69]) by smtp.gmail.com with ESMTPSA id aq25sm9329133ejc.11.2020.07.13.01.19.21 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Mon, 13 Jul 2020 01:19:22 -0700 (PDT) To: Jens Axboe , io-uring@vger.kernel.org References: <618bc9a5-420c-b176-df86-260734270f56@gmail.com> <3b3ee104-ee6b-7147-0677-bd0eb4efe76e@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: [RFC 0/9] scrap 24 bytes from io_kiocb Message-ID: <755ed6b1-ad23-ea48-6b15-1e7e358c1975@gmail.com> Date: Mon, 13 Jul 2020 11:17:36 +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: <3b3ee104-ee6b-7147-0677-bd0eb4efe76e@kernel.dk> 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 12/07/2020 23:32, Jens Axboe wrote: > On 7/12/20 11:34 AM, Pavel Begunkov wrote: >> On 12/07/2020 18:59, Jens Axboe wrote: >>> On 7/12/20 3:41 AM, Pavel Begunkov wrote: >>>> Make io_kiocb slimmer by 24 bytes mainly by revising lists usage. The >>>> drawback is adding extra kmalloc in draining path, but that's a slow >>>> path, so meh. It also frees some space for the deferred completion path >>>> if would be needed in the future, but the main idea here is to shrink it >>>> to 3 cachelines in the end. >>>> >>>> I'm not happy yet with a few details, so that's not final, but it would >>>> be lovely to hear some feedback. >>> >>> I think it looks pretty good, most of the changes are straight forward. >>> Adding a completion entry that shares the submit space is a good idea, >>> and really helps bring it together. >>> >>> From a quick look, the only part I'm not super crazy about is patch #3. >> >> Thanks! >> >>> I'd probably rather use a generic list name and not unionize the tw >>> lists. >> >> I don't care much, but without compiler's help always have troubles >> finding and distinguishing something as generic as "list". > > To me, it's easier to verify that we're doing the right thing when they > use the same list member. Otherwise you have to cross reference two > different names, easier to shoot yourself in the foot that way. So I'd > prefer just retaining it as 'list' or something generic. If you don't have objections, I'll just leave it "inflight_entry". This one is easy to grep. >> BTW, I thought out how to bring it down to 3 cache lines, but that would >> require taking io_wq_work out of io_kiocb and kmalloc'ing it on demand. >> And there should also be a bunch of nice side effects like improving apoll. > > How would this work with the current use of io_wq_work as storage for > whatever bits we're hanging on to? I guess it could work with a prep > series first more cleanly separating it, though I do feel like we've > been getting closer to that already. It's definitely not a single patch. I'm going to prepare a series for discussion later, and then we'll see whether it worths it. > Definitely always interested in shrinking io_kiocb, just need to keep > an eye out for the fast(er) paths not needing two allocations (and > frees) for a single request. -- Pavel Begunkov