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 89BB5423AF for ; Wed, 11 Jan 2023 21:14:32 +0100 (CET) Received: from mails.dpdk.org (localhost [127.0.0.1]) by mails.dpdk.org (Postfix) with ESMTP id 6486342C54; Wed, 11 Jan 2023 21:14:32 +0100 (CET) Received: from mail-lj1-f169.google.com (mail-lj1-f169.google.com [209.85.208.169]) by mails.dpdk.org (Postfix) with ESMTP id 27A9E40A7D for ; Wed, 11 Jan 2023 21:14:31 +0100 (CET) Received: by mail-lj1-f169.google.com with SMTP id s25so17217757lji.2 for ; Wed, 11 Jan 2023 12:14:31 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20210112; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:subject:cc:to:from:date:from:to:cc:subject:date :message-id:reply-to; bh=c7jT1IAJij2MnVWbj82Xz9HZjaUaYTNyLFOQgmuu69E=; b=B8sEYxufX/4i42/sRj28iEqzdQEG9sCWHkWNva3mI7sXrnhm4thsfLrc58U+pLGgbr tTOUx0dmqENs5zSHCl9xz1yWIfShY5iCfQ8G2yR52jh30o7UuOx2Dpozn23ZHhVASrxY aGWsF1xC/Va5sEIgCFZNJsX2eUT7Zo/UXYpKwuDHneI6UfvVmLNvRLdVgChlavfSFkAR VOuAmW3Ha+Df8IaliC65jhBja0+mU00skIGjY1TohHXheK3mrkMKZasNi/v6GjibinL+ MXe1J9TqLRjXr6hHys+aN4zMFTX1R7bTlQ0qb+IECZAKIXtQLz1/z6dCpBaFzIoTbX5y YYag== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=content-transfer-encoding:mime-version:references:in-reply-to :message-id:subject:cc:to:from:date:x-gm-message-state:from:to:cc :subject:date:message-id:reply-to; bh=c7jT1IAJij2MnVWbj82Xz9HZjaUaYTNyLFOQgmuu69E=; b=g6dAiwzPCiMZRY4zwNZPI23J2l0y4R3UvBNG8zTsX/e31hkgOcjEFTOeUych2Z9uhI RE9D05cT8411t8a5bMiJHDPL8s2AoKWBa+YmvgUCpcAPBUpywIPMwQamEBEQuZkxJ1uy dlgLbWXDv4b3gUgd/FyREmwNtXrmsGXjKU0YXm6gxKto3URSONsgZj42w6jIBgypommR UVchNOMZWLUMqKTtLEvANo2/v+xUBTUevNyOTWM7X8uXvt5EIGQpl/AEY4/3n8/wYaw/ JwcX4GbuFoeY6x0PZHsj/LXv1LcITgEwk6DhqsmwP49ixzutbAJy4b2/ql4H7UOI0O2Y M+yg== X-Gm-Message-State: AFqh2koiKSnpTQG53s9wUjQ1i89Jfgt1+tkR0BNdc9/r+bzYnxS1VEE+ dqTitsAzSbonYD9CsCt7MCY= X-Google-Smtp-Source: AMrXdXvFlC9X2iKj0x20ke63b7eTf+j2PW7PEMC0ii3jLjbRULUYXDho6LC5Q63L3JrYK6xwjQb+nw== X-Received: by 2002:a2e:9058:0:b0:287:2d2a:453f with SMTP id n24-20020a2e9058000000b002872d2a453fmr2070459ljg.22.1673468070562; Wed, 11 Jan 2023 12:14:30 -0800 (PST) Received: from sovereign (broadband-37-110-65-23.ip.moscow.rt.ru. [37.110.65.23]) by smtp.gmail.com with ESMTPSA id r4-20020a2e8e24000000b00283ad9caa59sm1542117ljk.140.2023.01.11.12.14.29 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 11 Jan 2023 12:14:30 -0800 (PST) Date: Wed, 11 Jan 2023 23:14:27 +0300 From: Dmitry Kozlyuk To: fwefew 4t4tg <7532yahoo@gmail.com> Cc: users@dpdk.org Subject: Re: DPDK and DMA Message-ID: <20230111231427.23b209a8@sovereign> In-Reply-To: References: <20230111142600.221cdc2e@sovereign> X-Mailer: Claws Mail 3.18.0 (GTK+ 2.24.33; x86_64-pc-linux-gnu) MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-BeenThere: users@dpdk.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: DPDK usage discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: users-bounces@dpdk.org 2023-01-11 13:05 (UTC-0500), fwefew 4t4tg: > Thank you for taking time to provide a nice reply. The upshot here is that > DPDK > already uses DMA in a smart way to move packet data into TXQs. I presume the > reverse also happens: NIC uses DMA to move packets out of its HW RXQs into > the host machine's memory using the mempool associated with it. Almost, except that the NIC does not know about mempools. It's DPDK PMD (as Stephen clarified) that allocates mbufs from mempool, does Rx descriptor setup to point to the buffers and then requests the NIC to write packet data to host RAM using DMA. If you want to study this area, take a look at "ixy" project family: https://github.com/ixy-languages/ixy-languages It's like "micro DPDK" for educational purposes.