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=-6.1 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, 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 37D23C433EF for ; Wed, 8 Sep 2021 10:25:41 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 16E4D6008E for ; Wed, 8 Sep 2021 10:25:41 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1346391AbhIHK0r (ORCPT ); Wed, 8 Sep 2021 06:26:47 -0400 Received: from mail.kernel.org ([198.145.29.99]:49578 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234958AbhIHK0q (ORCPT ); Wed, 8 Sep 2021 06:26:46 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id D5BE56113A; Wed, 8 Sep 2021 10:25:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1631096739; bh=NiCfI13R4LrvaT+owBE7g+4UJWIO/e9R5b5MoX02Png=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=gas+Gt4RivH1IpU96+UkUeQZJJ74+BIM5F6tA36+SvsipUXg44ungmeVaSPR0N37d WHog008RdrlsReaMXEyNzOUhjPEUew0gFSLtz6EsR/p8sv6g5kzRD3Tmm2S85M+WGz gRbT1y/EmznblAlZN9EAYaX6UW8vsBOtEEZGp4H0= Date: Wed, 8 Sep 2021 12:25:36 +0200 From: Greg Kroah-Hartman To: Pavel Begunkov Cc: Arnd Bergmann , linux-kernel@vger.kernel.org, Jens Axboe , io-uring@vger.kernel.org Subject: Re: [PATCH] /dev/mem: nowait zero/null ops Message-ID: References: <16c78d25f507b571df7eb852a571141a0fdc73fd.1631095567.git.asml.silence@gmail.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <16c78d25f507b571df7eb852a571141a0fdc73fd.1631095567.git.asml.silence@gmail.com> Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org On Wed, Sep 08, 2021 at 11:06:51AM +0100, Pavel Begunkov wrote: > Make read_iter_zero() to honor IOCB_NOWAIT, so /dev/zero can be > advertised as FMODE_NOWAIT. This helps subsystems like io_uring to use > it more effectively. Set FMODE_NOWAIT for /dev/null as well, it never > waits and therefore trivially meets the criteria. I do not understand, why would io_uring need to use /dev/zero and how is this going to help anything? What workload does this help with? thanks, greg k-h