From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mails.dpdk.org (mails.dpdk.org [217.70.189.124]) by inbox.dpdk.org (Postfix) with ESMTP id E2BBBA054F; Mon, 1 Mar 2021 16:44:03 +0100 (CET) Received: from [217.70.189.124] (localhost [127.0.0.1]) by mails.dpdk.org (Postfix) with ESMTP id 7500422A2CE; Mon, 1 Mar 2021 16:44:03 +0100 (CET) Received: from out0-152.mail.aliyun.com (out0-152.mail.aliyun.com [140.205.0.152]) by mails.dpdk.org (Postfix) with ESMTP id 9B13940041 for ; Mon, 1 Mar 2021 16:44:01 +0100 (CET) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=alibaba-inc.com; s=default; t=1614613438; h=Subject:To:From:Message-ID:Date:MIME-Version:Content-Type; bh=N03m1zZVmZVOum7upOAeLKz6DiiaFrS69OHvT/wJU20=; b=ZtPo0xERjg9iWC+NfKM2Vop8zs7k0UqZS4FaoPFgyv79q53Q5LskLOKuU/3NtS7bTcnoYQfRyRXiLnmgaRBjdwLSYFeupZHjSMPwHIQvJc/J+WgiYu0TwGc6R4TSdQ5aNeGMeI1dwNAvDeFy9uUSCTxSOVkF3OdhjtMiWeBg2Hc= X-Alimail-AntiSpam: AC=PASS; BC=-1|-1; BR=01201311R191e4; CH=green; DM=||false|; DS=||; FP=0|-1|-1|-1|0|-1|-1|-1; HT=ay29a033018047188; MF=huawei.xhw@alibaba-inc.com; NM=1; PH=DS; RN=8; SR=0; TI=SMTPD_---.JeyCER0_1614613436; Received: from 30.15.219.167(mailfrom:huawei.xhw@alibaba-inc.com fp:SMTPD_---.JeyCER0_1614613436) by smtp.aliyun-inc.com(127.0.0.1); Mon, 01 Mar 2021 23:43:57 +0800 To: David Marchand Cc: Ferruh Yigit , Maxime Coquelin , dev , "Burakov, Anatoly" , xuemingl@nvidia.com, Gaetan Rivet , "Xia, Chenbo" References: <1611890309-99135-1-git-send-email-huawei.xhw@alibaba-inc.com> <1614014118-91150-1-git-send-email-huawei.xhw@alibaba-inc.com> <1614014118-91150-3-git-send-email-huawei.xhw@alibaba-inc.com> <08e5172f-36ce-13d9-5c96-9d6d1e71153a@intel.com> <967cfffb-1955-afc2-8479-0afa255b317f@alibaba-inc.com> From: "=?UTF-8?B?6LCi5Y2O5LyfKOatpOaXtuatpOWIu++8iQ==?=" Message-ID: <85a43efe-ef66-54c0-81b4-6e130a987699@alibaba-inc.com> Date: Mon, 01 Mar 2021 23:43:50 +0800 User-Agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64; rv:78.0) Gecko/20100101 Thunderbird/78.7.1 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US Subject: Re: [dpdk-dev] [PATCH v7 2/2] bus/pci: support MMIO in PCI ioport accessors X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org Sender: "dev" On 2021/2/25 17:52, David Marchand wrote: > On Thu, Feb 25, 2021 at 5:00 AM 谢华伟(此时此刻） wrote: >>>>> Is the 'outb_p' to 'outb' conversion intentional? And if so why? >>>>> >>>>> Same of the all 'outb_p', 'outw_p', 'outl_p'. >>>> There is no need to delay for virtio device, as we can see in virtio >>>> legacy driver. >>>> >>>> IMO, the delay is for ugly old device. The device itself should >>>> assure the previous IO completes when the subsequent IO instruction >>>> arrives. >>>> >>> Can there be any virtio legacy device needing this? >> The pause version delays sometime by writing to 0x80 debug port. virtio >> doesn't need this. virtio legacy PMD driver doens't use this. >> >> Any device relying on this i think is buggy. How could the device rely >> on some uncertain cpu cycles to behave correct? >> >>> What is the downside of using "pause until the I/O completes" versions? >> The downside in virtio PMD is a small performance penalty when we use it >> to notify backend. CPU executes unnecessary serializing IO instruction. >> >> I check kernel code, io wrapper for in/out doesn't use p version. > This change is a fix/optimisation. > This is a separate topic from adding MMIO support with x86 ioport. > I would split as a separate patch. Hi David: Maybe there is confuse? There is no change. The out/in is added. I don't remove _p on purpose. > >