From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wg0-f42.google.com (mail-wg0-f42.google.com [74.125.82.42]) by dpdk.org (Postfix) with ESMTP id 461DE58E0 for ; Mon, 19 May 2014 14:32:54 +0200 (CEST) Received: by mail-wg0-f42.google.com with SMTP id y10so7658176wgg.1 for ; Mon, 19 May 2014 05:33:03 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20130820; h=x-gm-message-state:from:to:cc:subject:date:message-id:organization :user-agent:in-reply-to:references:mime-version :content-transfer-encoding:content-type; bh=cizF9HwS7HC/BhjF0TOaKJ6Cg800vCBqqW+kVrJv1k4=; b=dVgpTY3IUqcAKGVAFy4IgZOEEvmDYdaVtQopY9E/QtYj65+yV8vDjtIXGcHgjR9RUI 0RQrJCaLK7nm4mzWQOBLhIc+jXOWEhlCbijyhPx+YvPVPVtm6qtH+ILwZzwOBr51IvIl s78ADZa3Q+auGFkKBgmRXWa5+JCTk5zpr1AHSmPixINkO7XvQ+9XL6KI8zWk0/ssCF8L hjHWqHTBuSa5BO+q52s3mmkV0DxrfdLV/g22pjN+xS0r4kgDNqss92cgPPcl7UfJweC1 QP4Xp49NsMY9Cdb54A+8gRW7mkkb3r1Y8rqE+0PEcptxLYag/7bY7nxSI+L1aPoIFCsq lbJQ== X-Gm-Message-State: ALoCoQkChp9PMvh00Y56f09kOrGIOPdnewCJsyXHj4Is41Lgz12wkDUq+K3ACuuOMUjRY9rrJxzW X-Received: by 10.194.187.107 with SMTP id fr11mr2592900wjc.70.1400502783032; Mon, 19 May 2014 05:33:03 -0700 (PDT) Received: from xps13.localnet (6wind.net2.nerim.net. [213.41.180.237]) by mx.google.com with ESMTPSA id nb8sm14837658wic.18.2014.05.19.05.33.00 for (version=TLSv1.2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 19 May 2014 05:33:01 -0700 (PDT) From: Thomas Monjalon To: "Ananyev, Konstantin" , Olivier MATZ Date: Mon, 19 May 2014 14:32:59 +0200 Message-ID: <1734202.xbDzyIthla@xps13> Organization: 6WIND User-Agent: KMail/4.13 (Linux/3.14.4-1-ARCH; KDE/4.13.0; x86_64; ; ) In-Reply-To: <2601191342CEEE43887BDE71AB9772580EFA6ED5@IRSMSX105.ger.corp.intel.com> References: <1399647038-15095-1-git-send-email-olivier.matz@6wind.com> <53760079.7090106@6wind.com> <2601191342CEEE43887BDE71AB9772580EFA6ED5@IRSMSX105.ger.corp.intel.com> MIME-Version: 1.0 Content-Transfer-Encoding: 7Bit Content-Type: text/plain; charset="us-ascii" Cc: dev@dpdk.org Subject: Re: [dpdk-dev] [PATCH RFC 11/11] ixgbe/mbuf: add TSO support X-BeenThere: dev@dpdk.org X-Mailman-Version: 2.1.15 Precedence: list List-Id: patches and discussions about DPDK List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , X-List-Received-Date: Mon, 19 May 2014 12:32:54 -0000 Hi, I'll try so sum it up this interesting discussion about checksum API for TSO. We know at least 2 checksum methods: - the standard one - the special one for ixgbe TSO In Linux ixgbe, checksum is redone in the driver for TSO case. We want to compute checksum in the application/stack in order to prevent driver from modifying packet data, that could cause cache miss. But the application cannot always know which checksum method to use because it doesn't have to know which driver will process the packet. So we have to choose which checksum method can be done in the application without driver processing. It's not an easy choice. It seems simpler and reasonnable to choose the standard pseudo-header checksum method as it is done in Linux. Having a stable and generic API is something important we must target. Thanks -- Thomas