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=-2.3 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,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 2CE52C43603 for ; Sat, 14 Dec 2019 18:43:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id F0FD220706 for ; Sat, 14 Dec 2019 18:43:52 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=kernel-dk.20150623.gappssmtp.com header.i=@kernel-dk.20150623.gappssmtp.com header.b="Mxx1kbGm" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726820AbfLNSnn (ORCPT ); Sat, 14 Dec 2019 13:43:43 -0500 Received: from mail-pg1-f196.google.com ([209.85.215.196]:41586 "EHLO mail-pg1-f196.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726358AbfLNSnm (ORCPT ); Sat, 14 Dec 2019 13:43:42 -0500 Received: by mail-pg1-f196.google.com with SMTP id x8so1222624pgk.8 for ; Sat, 14 Dec 2019 10:43:42 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel-dk.20150623.gappssmtp.com; s=20150623; h=subject:to:references:from:message-id:date:user-agent:mime-version :in-reply-to:content-language:content-transfer-encoding; bh=QbzwIxwiBFo2cffoX1L047KjXjiOr4rf4SxlZuAhMrY=; b=Mxx1kbGm0XFApeOmkSnbAtCAJM74EDCCF8bxEFFLrIiHYpH99UvvEkjQ4pgCeSK8IA ZEsHxCPSZEgTrksBJIT61B+gw9G5fs89J4RzYKG0pv3u4t+rEoAgfq/azFGYLkSBa18+ 5Syf7b5XnU0yWLcR0GQmoFbNKZsZ1xd3qfLPSGGCyqoRiHCtnvYlJhtqz7pf/ZRj3Qi3 gcghiGyr28AfdNoOfIGJxr+WLyD2LcE3FEVMIaRmSXtzNKBCzD+Ff/tM02BL2B3cIKbR WqQb7TQnNM4WErVb/MNbQD7F9cgZ+N2g+xH+6Ppt30Pr+ObJM/WR+w19vM8dDb4WQPox UK0Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:subject:to:references:from:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=QbzwIxwiBFo2cffoX1L047KjXjiOr4rf4SxlZuAhMrY=; b=ZyPd39MaZdUTpgpUlVEUkmdtOyelDBW3BisJOFM43Y796aI7raWUhC1y1DYghLcDwu Axti1UjfGPhmq5DuzofSm3lpRhM2j1Yw94LjoyRgxOBrWU7CkHGtxRrtkceVXm1kbtMS wBzuSodqgyFr1271y1OtuYpx2IBG/s93jbbp/TNnTmxs89MH/FRZWHWfNp9x5wAE3N+O 2681Tx4boAs9/kT8rTF5+lVbHRAYfUQIqxpDmMrvXKvwdBGHfNKrNJLYigDstmyORiQN gJGGw3qRfszVwVSLXUqzAPdkpX0DojNoCZeQzQVqcIblsmj2R/H0+Mg2oKNGgK2w8l1c gvGw== X-Gm-Message-State: APjAAAU597kG/EWpKse7OtiCi68qkjJPxQfxuAtrN/LpgvLbvkTceGp8 qRhM8/3xVYyWhX9NbJXcFMuXIAg9h6S7dQ== X-Google-Smtp-Source: APXvYqzRVHXJbkaHToZpXQuBbgfNfNrwyA7GnRMI4cTusCicSSlssbKOJWnBtTcZWc4BIUpjcxob9A== X-Received: by 2002:a63:5d03:: with SMTP id r3mr6986201pgb.306.1576349021449; Sat, 14 Dec 2019 10:43:41 -0800 (PST) Received: from [192.168.1.188] ([66.219.217.145]) by smtp.gmail.com with ESMTPSA id m15sm15216850pgi.91.2019.12.14.10.43.39 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Sat, 14 Dec 2019 10:43:39 -0800 (PST) Subject: Re: [PATCH v3] io_uring: don't wait when under-submitting To: Pavel Begunkov , io-uring@vger.kernel.org, linux-kernel@vger.kernel.org References: <6256169d519f72fe592e70be47a04aa0e9c3b9a1.1576333754.git.asml.silence@gmail.com> From: Jens Axboe Message-ID: Date: Sat, 14 Dec 2019 11:43:37 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.2.2 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 12/14/19 7:53 AM, Pavel Begunkov wrote: > There is no reliable way to submit and wait in a single syscall, as > io_submit_sqes() may under-consume sqes (in case of an early error). > Then it will wait for not-yet-submitted requests, deadlocking the user > in most cases. > > In such cases adjust min_complete, so it won't wait for more than > what have been submitted in the current call to io_uring_enter(). It > may be less than totally in-flight including previous submissions, > but this shouldn't do harm and up to a user. Thanks, applied. -- Jens Axboe