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=-2.1 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, 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 9417FC33CB2 for ; Fri, 31 Jan 2020 09:52:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 66164206F0 for ; Fri, 31 Jan 2020 09:52:34 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="tFa2xXLP" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728243AbgAaJwd (ORCPT ); Fri, 31 Jan 2020 04:52:33 -0500 Received: from mail-lf1-f68.google.com ([209.85.167.68]:40447 "EHLO mail-lf1-f68.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728160AbgAaJwd (ORCPT ); Fri, 31 Jan 2020 04:52:33 -0500 Received: by mail-lf1-f68.google.com with SMTP id c23so4430903lfi.7; Fri, 31 Jan 2020 01:52:30 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=subject:to:cc:references:from:message-id:date:user-agent :mime-version:in-reply-to:content-language:content-transfer-encoding; bh=2zLinx65kFK53ILK1AcLmmd59Fu+8auTjozCt4FuyXc=; b=tFa2xXLPMfbQa4Lg+mSI8s/TlT4TEzvbjICetoMKNxdwsGqzYXd99yW1obFpVYoOS4 f8Gbz5MIV2/PXrL+s/pjZtrbShpOtC2tKv+BLM5WSbYiBfTxAXxn5fa9/SyBtl5oHAdE OSnzwoFVXEhFweNJQ0O0/gS3uMzcAgcfrEOJ5Czh3qv4KSoxVWzGDiNr/QV1Ne4UJ+n8 1WSiDCeF31WdwWWjWg9C1Q9fYze+ZMMgpDo1L3z0c/izJuNZw6VnInN3LoxbA8yeEWMp RTIt6xMq7wgtger92/GnJMXCeje8Cv1s+uiRxVEaDF/U2VIWd0T1AzS667H57mwt6iwn VrnA== 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:message-id:date :user-agent:mime-version:in-reply-to:content-language :content-transfer-encoding; bh=2zLinx65kFK53ILK1AcLmmd59Fu+8auTjozCt4FuyXc=; b=Bynxe7cbs/20JuuUp/Bv7LvTnz6LOS+Z+YSR04hwl5gQSi1uDI3vIsocRiBZK2nfUK a/2nKKLzb/xlwlFQKmhZqSJw0uW96ITbWZQ/58FbXFkT/c7K3YU4gx3sM/sHPeQaQoE8 bR+7lqg0teRZE8XTpKy4Bd44Ae0SdtzhHcd6Wh3lu9be1OhnIwySoXJ6kyuJgK92uHvU wD/xqzA/fFcq6TYnAbjDZnj6qi6J4CwEMEStbONUfWt3N9/Y2gXY0a9ute6qc2OPacZi LF7xW05e0LTG0WmPqE/IZGC0ChDgeWRymxYBSJJNQ8RtRtEYUo94Y8AY4SJZtRJw0AkX Vv+Q== X-Gm-Message-State: APjAAAXiWlKvqW5C1yQKi6GQjmuZioaj3Lu9kjAXsBBUO9Nt4RX0+oeh /dIHt9dmCxTKC+8eVFklCBilCMdUmfo= X-Google-Smtp-Source: APXvYqzYXjb3R9IBvegkSpqNYMQIIrmty+2pa0JXh83XjZcPtPYUYfTGQjgzU3IyYAFO0mtvD25YyA== X-Received: by 2002:a19:9d0:: with SMTP id 199mr5092184lfj.110.1580464349406; Fri, 31 Jan 2020 01:52:29 -0800 (PST) Received: from [172.31.190.83] ([86.57.146.226]) by smtp.gmail.com with ESMTPSA id p9sm4380158ljg.55.2020.01.31.01.52.28 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Fri, 31 Jan 2020 01:52:28 -0800 (PST) Subject: Re: [PATCH] splice: direct call for default_file_splice*() To: Christoph Hellwig Cc: Alexander Viro , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org References: <12375b7baa741f0596d54eafc6b1cfd2489dd65a.1579553271.git.asml.silence@gmail.com> <20200130165425.GA8872@infradead.org> From: Pavel Begunkov Message-ID: <239aacf6-5f8b-39f4-b4f0-e22de4c46b88@gmail.com> Date: Fri, 31 Jan 2020 12:52:27 +0300 User-Agent: Mozilla/5.0 (Windows NT 10.0; WOW64; rv:68.0) Gecko/20100101 Thunderbird/68.4.2 MIME-Version: 1.0 In-Reply-To: <20200130165425.GA8872@infradead.org> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On 1/30/2020 7:54 PM, Christoph Hellwig wrote: > On Mon, Jan 20, 2020 at 11:49:46PM +0300, Pavel Begunkov wrote: >> Indirect calls could be very expensive nowadays, so try to use direct calls >> whenever possible. > > ... and independent of that your new version is much shorter and easier > to read. But it could be improved a tiny little bit further: > >> if (out->f_op->splice_write) >> - splice_write = out->f_op->splice_write; >> + return out->f_op->splice_write(pipe, out, ppos, len, flags); >> else >> - splice_write = default_file_splice_write; >> - >> - return splice_write(pipe, out, ppos, len, flags); >> + return default_file_splice_write(pipe, out, ppos, len, flags); > > No need for the else after an return. It generates identical binary. For this to not look sloppy, I'd add new line between, so the same 4 lines. And this looks better for me, but that's rather subjective. I don't think it's worth of changing. What's the benefit? > >> if (in->f_op->splice_read) >> - splice_read = in->f_op->splice_read; >> + return in->f_op->splice_read(in, ppos, pipe, len, flags); >> else >> - splice_read = default_file_splice_read; >> - >> - return splice_read(in, ppos, pipe, len, flags); >> + return default_file_splice_read(in, ppos, pipe, len, flags); > > Same here. > -- Pavel Begunkov