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=-3.9 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS 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 D36BDC433E1 for ; Fri, 21 Aug 2020 13:55:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id AEB9B20720 for ; Fri, 21 Aug 2020 13:55:59 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=datadoghq.com header.i=@datadoghq.com header.b="X9AF6VC4" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728789AbgHUNz7 (ORCPT ); Fri, 21 Aug 2020 09:55:59 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39168 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727123AbgHUNz6 (ORCPT ); Fri, 21 Aug 2020 09:55:58 -0400 Received: from mail-yb1-xb41.google.com (mail-yb1-xb41.google.com [IPv6:2607:f8b0:4864:20::b41]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 40C8BC061573 for ; Fri, 21 Aug 2020 06:55:58 -0700 (PDT) Received: by mail-yb1-xb41.google.com with SMTP id m200so1070592ybf.10 for ; Fri, 21 Aug 2020 06:55:58 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=datadoghq.com; s=google; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=252+vJaMVsbLgAEy+MzraO+zqIdAzi/sOZ+rVR5WF1g=; b=X9AF6VC4MdLAH+AwxrK78kxxmwMsRqRms5PEGXMizn79HWz3elIkqSrS9ns39MQK3a j85WzuLrMFR3OplZLSa7D64ZHoZbqCgUVkAPFjNLqDC56wKMFdn4jYnftAY6A4XHntrQ iHIv/5+IjuxMu2/duUAcbjr1VDbpKqXeS5KUE= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=252+vJaMVsbLgAEy+MzraO+zqIdAzi/sOZ+rVR5WF1g=; b=ZyNIfB1w45BijZtAxHaKHZqkBniMVL+c9pII1G1lkeDh4hw02eL42Vs9lSPrnWMJa/ 8qeIwxN/2H8EQm9RlVw6ZXkdbzdp6MYSK4EswH8ijNJX6dPMXz1FHKSt0FGACizgkn3t Og0wh6obTk/OFJsNCcjSenEcQvezk6IQLbUle/8zuZLiIbQio0Os0BvUBD1ijSezpeDv wNfqWmi2xxzZlNNtpueLeFHc4Wn3khQshPcr7fBhhsg6wCNKRrSdxti+hH+CUCy4N/r5 mL2Aa7RQU9NwQGYQi43UQi2gXaNrPxNyT+xvfd0tY7mMNlxznFIJewCJBfIQvRl/zdyp LH8w== X-Gm-Message-State: AOAM530AujAmsRWioKeG2k3KmUWFlA+fsoMSGDz9MEDW1okM0Nz/+tvZ bVU/YxfuQJ7t33XpLOIGAjOraqCg24BB2obQVDH9WXIJ1qM= X-Google-Smtp-Source: ABdhPJxlfU6/Dk1sJ8T8f8PI9QzfaFeTCGZ0JgOIlb1p5TkrHN/Wwbp9kkDqZyU/fF74Tx8fHMrGedEVM1jrSZkc7A0= X-Received: by 2002:a25:6908:: with SMTP id e8mr4251795ybc.83.1598018157494; Fri, 21 Aug 2020 06:55:57 -0700 (PDT) MIME-Version: 1.0 References: <8d8870de-909a-d05d-51a5-238f5c59764d@kernel.dk> <8f509999-bfe3-c99b-6e82-dc604865ce9e@kernel.dk> In-Reply-To: <8f509999-bfe3-c99b-6e82-dc604865ce9e@kernel.dk> From: Glauber Costa Date: Fri, 21 Aug 2020 09:55:46 -0400 Message-ID: Subject: Re: Poll ring behavior broken by f0c5c54945ae92a00cdbb43bdf3abaeab6bd3a23 To: Jens Axboe Cc: io-uring@vger.kernel.org, xiaoguang.wang@linux.alibaba.com Content-Type: text/plain; charset="UTF-8" Sender: io-uring-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org On Thu, Aug 20, 2020 at 11:42 PM Jens Axboe wrote: > > On 8/20/20 8:24 PM, Glauber Costa wrote: > > On Thu, Aug 20, 2020 at 9:57 PM Jens Axboe wrote: > >> > >> On 8/20/20 6:46 PM, Glauber Costa wrote: > >>> I have just noticed that the commit in $subject broke the behavior I > >>> introduced in > >>> bf3aeb3dbbd7f41369ebcceb887cc081ffff7b75 > >>> > >>> In this commit, I have explained why and when it does make sense to > >>> enter the ring if there are no sqes to submit. > >>> > >>> I guess one could argue that in that case one could call the system > >>> call directly, but it is nice that the application didn't have to > >>> worry about that, had to take no conditionals, and could just rely on > >>> io_uring_submit as an entry point. > >>> > >>> Since the author is the first to say in the patch that the patch may > >>> not be needed, my opinion is that not only it is not needed but in > >>> fact broke applications that relied on previous behavior on the poll > >>> ring. > >>> > >>> Can we please revert? > >> > >> Yeah let's just revert it for now. Any chance you can turn this into > >> a test case for liburing? Would help us not break this in the future. > > > > would be my pleasure. > > > > Biggest issue is that poll mode really only works with ext4 and xfs as > > far as I know. That may mean it won't get as much coverage, but maybe > > that's not relevant. > > And raw nvme too, of course. But I'd say coverage is pretty decent with > those two, in reality that's most likely what people would use for > polling anyway. So not too concerned about that, and it'll hit multiple > items in my test suite. > > I reverted the change manually, it didn't revert cleanly. Please test > current -git, thanks! > Just tested (through a new unit test) and it works, thanks. I wrote a unit test that works on HEAD but not on HEAD^. However you will have to excuse my lack of manners, but in my new work account I can't have app passwords for GSuite so I am unable to git-send-email it without talking to a host of corporate IT people... I'll have to send a ... urgh... PR > -- > Jens Axboe >