From mboxrd@z Thu Jan 1 00:00:00 1970 From: Thomas Monjalon Subject: Re: [PATCH RFC 11/11] ixgbe/mbuf: add TSO support Date: Mon, 19 May 2014 14:32:59 +0200 Message-ID: <1734202.xbDzyIthla@xps13> 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-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7Bit Cc: dev-VfR2kkLFssw@public.gmane.org To: "Ananyev, Konstantin" , Olivier MATZ Return-path: In-Reply-To: <2601191342CEEE43887BDE71AB9772580EFA6ED5-kPTMFJFq+rEu0RiL9chJVbfspsVTdybXVpNB7YpNyf8@public.gmane.org> List-Id: patches and discussions about DPDK List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces-VfR2kkLFssw@public.gmane.org Sender: "dev" 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