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=-3.8 required=3.0 tests=BAYES_00, 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 1ED04C48BE8 for ; Fri, 18 Jun 2021 21:38:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 071E06128C for ; Fri, 18 Jun 2021 21:38:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234604AbhFRVkY (ORCPT ); Fri, 18 Jun 2021 17:40:24 -0400 Received: from cloud48395.mywhc.ca ([173.209.37.211]:54136 "EHLO cloud48395.mywhc.ca" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230399AbhFRVkW (ORCPT ); Fri, 18 Jun 2021 17:40:22 -0400 Received: from modemcable064.203-130-66.mc.videotron.ca ([66.130.203.64]:33082 helo=[192.168.1.179]) by cloud48395.mywhc.ca with esmtpsa (TLS1.2) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.94.2) (envelope-from ) id 1luMBo-0003I9-9r; Fri, 18 Jun 2021 17:38:12 -0400 Message-ID: <489a3a2ded1daf962b8bfa3c936e20526b975d1a.camel@trillion01.com> Subject: Re: [PATCH] io_uring: reduce latency by reissueing the operation From: Olivier Langlois To: Jens Axboe , Pavel Begunkov , io-uring@vger.kernel.org, linux-kernel@vger.kernel.org Date: Fri, 18 Jun 2021 17:38:11 -0400 In-Reply-To: References: <60c13bec.1c69fb81.f2c1e.6444SMTPIN_ADDED_MISSING@mx.google.com> Organization: Trillion01 Inc Content-Type: text/plain; charset="ISO-8859-1" User-Agent: Evolution 3.40.2 MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-AntiAbuse: This header was added to track abuse, please include it with any abuse report X-AntiAbuse: Primary Hostname - cloud48395.mywhc.ca X-AntiAbuse: Original Domain - vger.kernel.org X-AntiAbuse: Originator/Caller UID/GID - [47 12] / [47 12] X-AntiAbuse: Sender Address Domain - trillion01.com X-Get-Message-Sender-Via: cloud48395.mywhc.ca: authenticated_id: olivier@trillion01.com X-Authenticated-Sender: cloud48395.mywhc.ca: olivier@trillion01.com X-Source: X-Source-Args: X-Source-Dir: Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, 2021-06-16 at 06:48 -0600, Jens Axboe wrote: > On 6/9/21 4:08 PM, Olivier Langlois wrote: > > It is quite frequent that when an operation fails and returns > > EAGAIN, > > the data becomes available between that failure and the call to > > vfs_poll() done by io_arm_poll_handler(). > > > > Detecting the situation and reissuing the operation is much faster > > than going ahead and push the operation to the io-wq. > > I think this is obviously the right thing to do, but I'm not too > crazy > about the 'ret' pointer passed in. We could either add a proper > return > type instead of the bool and use that, or put the poll-or-queue-async > into a helper that then only needs a bool return, and use that return > value for whether to re-issue or not. > > Care to send an updated variant? > No problem! It is going to be pleasure to send an updated version with the requested change! I will take that opportunity to try out my new patch sending setup ;-)