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=-9.3 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,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 EF0B0C4332B for ; Mon, 11 Jan 2021 05:01:50 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id D3E68225AB for ; Mon, 11 Jan 2021 05:01:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1725355AbhAKFBn (ORCPT ); Mon, 11 Jan 2021 00:01:43 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:57078 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1725957AbhAKFBg (ORCPT ); Mon, 11 Jan 2021 00:01:36 -0500 Received: from mail-wr1-x42f.google.com (mail-wr1-x42f.google.com [IPv6:2a00:1450:4864:20::42f]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 18E19C061786 for ; Sun, 10 Jan 2021 21:00:56 -0800 (PST) Received: by mail-wr1-x42f.google.com with SMTP id r3so15015012wrt.2 for ; Sun, 10 Jan 2021 21:00:55 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=subject:to:cc:references:from:autocrypt:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=xXyJy4Jl9Gixg5IQJawAFvSwzTBE/lE//iqjeXylgWY=; b=Ht7qG8vm6fP+0mF/lf5RsmKtXTqO6SNmBQehW1YiGEDZeWvbPnJws5oc6gb8XKByzk v8xEviv3kvu/0N1M96edruYRE++5iJzC6BxqOEGqJ141et+F1utJLvN8E97oOafUlCn0 rRRrYPpV1oXnov51KV6uVqB7lZMM7GvQRC3U7lCjqLqctCdCxq58SKPTc3h1fU4rIT0X 4OL6axpVayGRQigyICIJfpcAPxDntwvyYYJ9OhQmLMLqFc4CTAfXFW7FZZLzAkcXEIWP vsVQbTglaknMh2UV05ASBcbXhepM+Qim8Oy5jqACE03UZPm9I+livJhLddHHc/gDZ5yN Pc2Q== 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:autocrypt :message-id:date:user-agent:mime-version:in-reply-to :content-language:content-transfer-encoding; bh=xXyJy4Jl9Gixg5IQJawAFvSwzTBE/lE//iqjeXylgWY=; b=FxV9rIi0a9J6RKuRC9Kl306mbuNJ2uuILXmB9VowVtEtxJ8z8Ve7rCpk6i617jrUAc 664cP+a4qODlkG+6Ba1TTkJIPN9RtVZqc9xh/KNstQoWBo05NXnsojpvEq67DF9HQ/HF 4R5vpzdYsXLEBodK94IJ0dYovywaXyYtAWmBZ0jeChFp0LTgT83D6kcV9EQN5rWmhLnA QZdq1r143t6ShHXzsqFjvpq7nZj4LvGN2wtDeUTnVxTEVv8p0bxp/XH/1y4fZATMOloa n0P3wIIpK8rAkbiZuHQybB5IWN2jdooP4Tf5On0/YdNcmU25Em0s+nrrpgaFZYXdd93X atGg== X-Gm-Message-State: AOAM5307WGWjXH8bjbkVqfFMA9QsulZjLgmxxnfFrOOo75b8nvx1cwrt gmzTxhL/vFUPyO985dzMGdKbV+mnzqg= X-Google-Smtp-Source: ABdhPJwa8nHdcDO1ytFPyPZPOxQKgMsTfikiGDL1Cyu4vEWYTb/gux0sOhlCxXpiqThvMdDUiMQ4fw== X-Received: by 2002:a5d:60c1:: with SMTP id x1mr14463017wrt.271.1610341254516; Sun, 10 Jan 2021 21:00:54 -0800 (PST) Received: from [192.168.8.119] ([85.255.237.6]) by smtp.gmail.com with ESMTPSA id n11sm25562133wra.9.2021.01.10.21.00.53 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sun, 10 Jan 2021 21:00:54 -0800 (PST) Subject: Re: [PATCH v2 2/2] io_uring: flush timeouts that should already have expired To: Marcelo Diop-Gonzalez Cc: axboe@kernel.dk, io-uring@vger.kernel.org References: <20201219191521.82029-1-marcelo827@gmail.com> <20201219191521.82029-3-marcelo827@gmail.com> <20210108155726.GA8655@marcelo-debian.domain> 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== Message-ID: <2fc9e651-d786-7c2d-0d2c-47ed454f06be@gmail.com> Date: Mon, 11 Jan 2021 04:57:21 +0000 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: <20210108155726.GA8655@marcelo-debian.domain> 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 08/01/2021 15:57, Marcelo Diop-Gonzalez wrote: > On Sat, Jan 02, 2021 at 08:26:26PM +0000, Pavel Begunkov wrote: >> On 02/01/2021 19:54, Pavel Begunkov wrote: >>> On 19/12/2020 19:15, Marcelo Diop-Gonzalez wrote: >>>> Right now io_flush_timeouts() checks if the current number of events >>>> is equal to ->timeout.target_seq, but this will miss some timeouts if >>>> there have been more than 1 event added since the last time they were >>>> flushed (possible in io_submit_flush_completions(), for example). Fix >>>> it by recording the starting value of ->cached_cq_overflow - >>>> ->cq_timeouts instead of the target value, so that we can safely >>>> (without overflow problems) compare the number of events that have >>>> happened with the number of events needed to trigger the timeout. >> >> https://www.spinics.net/lists/kernel/msg3475160.html >> >> The idea was to replace u32 cached_cq_tail with u64 while keeping >> timeout offsets u32. Assuming that we won't ever hit ~2^62 inflight >> requests, complete all requests falling into some large enough window >> behind that u64 cached_cq_tail. >> >> simplifying: >> >> i64 d = target_off - ctx->u64_cq_tail >> if (d <= 0 && d > -2^32) >> complete_it() >> >> Not fond of it, but at least worked at that time. You can try out >> this approach if you want, but would be perfect if you would find >> something more elegant :) >> > > What do you think about something like this? I think it's not totally > correct because it relies on having ->completion_lock in io_timeout() so > that ->cq_last_tm_flushed is updated, but in case of IORING_SETUP_IOPOLL, > io_iopoll_complete() doesn't take that lock, and ->uring_lock will not > be held if io_timeout() is called from io_wq_submit_work(), but maybe > could still be worth it since that was already possibly a problem? I'll take a look later, but IOPOLL doesn't support timeouts, see the first if in io_timeout_prep(), so that's not a problem, but would better to leave a comment. > > diff --git a/fs/io_uring.c b/fs/io_uring.c > index cb57e0360fcb..50984709879c 100644 > --- a/fs/io_uring.c > +++ b/fs/io_uring.c > @@ -353,6 +353,7 @@ struct io_ring_ctx { > unsigned cq_entries; > unsigned cq_mask; > atomic_t cq_timeouts; > + unsigned cq_last_tm_flush; > unsigned long cq_check_overflow; > struct wait_queue_head cq_wait; > struct fasync_struct *cq_fasync; > @@ -1633,19 +1634,26 @@ static void __io_queue_deferred(struct io_ring_ctx *ctx) > > static void io_flush_timeouts(struct io_ring_ctx *ctx) > { > + u32 seq = ctx->cached_cq_tail - atomic_read(&ctx->cq_timeouts); > + > while (!list_empty(&ctx->timeout_list)) { > + u32 events_needed, events_got; > struct io_kiocb *req = list_first_entry(&ctx->timeout_list, > struct io_kiocb, timeout.list); > > if (io_is_timeout_noseq(req)) > break; > - if (req->timeout.target_seq != ctx->cached_cq_tail > - - atomic_read(&ctx->cq_timeouts)) > + > + events_needed = req->timeout.target_seq - ctx->cq_last_tm_flush; > + events_got = seq - ctx->cq_last_tm_flush; > + if (events_got < events_needed) > break; > > list_del_init(&req->timeout.list); > io_kill_timeout(req); > } > + > + ctx->cq_last_tm_flush = seq; > } > > static void io_commit_cqring(struct io_ring_ctx *ctx) > -- Pavel Begunkov