From mboxrd@z Thu Jan 1 00:00:00 1970 From: "didier.pallard" Subject: Re: [PATCH v4 3/3] mbuf:replace the inner_l2_len and the inner_l3_len fields Date: Tue, 02 Dec 2014 15:53:29 +0100 Message-ID: <547DD269.2080500@6wind.com> References: <1417503172-18642-1-git-send-email-jijiang.liu@intel.com> <1417503172-18642-4-git-send-email-jijiang.liu@intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit To: jijiang.liu-ral2JQCrhuEAvxtiuMwx3w@public.gmane.org, dev-VfR2kkLFssw@public.gmane.org Return-path: In-Reply-To: <1417503172-18642-4-git-send-email-jijiang.liu-ral2JQCrhuEAvxtiuMwx3w@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" Hello, On 12/02/2014 07:52 AM, Jijiang Liu wrote: > Replace the inner_l2_len and the inner_l3_len field with the outer_l2_len and outer_l3_len field, and rework csum forward engine and i40e PMD due to these changes. > > Signed-off-by: Jijiang Liu [...] > --- a/lib/librte_mbuf/rte_mbuf.h > +++ b/lib/librte_mbuf/rte_mbuf.h > @@ -276,8 +276,8 @@ struct rte_mbuf { > uint64_t tso_segsz:16; /**< TCP TSO segment size */ > > /* fields for TX offloading of tunnels */ > - uint64_t inner_l3_len:9; /**< inner L3 (IP) Hdr Length. */ > - uint64_t inner_l2_len:7; /**< inner L2 (MAC) Hdr Length. */ > + uint64_t outer_l3_len:9; /**< Outer L3 (IP) Hdr Length. */ > + uint64_t outer_l2_len:7; /**< Outer L2 (MAC) Hdr Length. */ > > /* uint64_t unused:8; */ > }; Sorry for entering lately this discussion, but i'm not convinced by the choice of outer_lx_len rather than inner_lx_len for new fields. I agree with Olivier that new flags should only be related to the use of new fields, to maintain coherency with oldest implementations. But from a stack point of view, i think it is better to have lx_len fields that target the outer layers, and to name new fields inner_lx_len. Let's discuss the two possibilities. 1) outer_lx_len fields are introduced. In this case, the stack should have knowledge that it is processing tunneled packets to use outer_lx_len rather than lx_len, or stack should always use outer_lx_len packet and move those fields to lx_len packets if no tunneling occurs... I think it will induce extra processing that does not seem to be really needed. 2) inner_lx_len fields are introduced. In this case, the stack first uses lx_len fields. When packet should be tunneled, lx_len fields are moved to inner_lx_len fields. Then the stack can process the outer layer and still use the lx_len fields. For example: an eth/IP/TCP forged packet will look like this: Ether/IP/UDP/xxx m->flags = IP_CKSUM m->l2_len = sizeof(ether) m->l3_len = sizeof(ip) m->l4_len = sizeof(udp) m->inner_l2_len = 0 m->inner_l3_len = 0 When entering tunnel for example a VXLAN interface, lx_len will be moved to inner_lx_len Ether/IP/UDP/xxx m->flags = INNER_IP_CKSUM m->l2_len = 0 m->l3_len = 0 m->l4_len = 0 m->inner_l2_len = sizeof(ether) m->inner_l3_len = sizeof(ip) once complete encapsulation is processed by the stack, the packet will look like Ether/IP/UDP/VXLAN/Ether/IP/UDP/xxx m->flags = IP_CKSUM | INNER_IP_CKSUM m->l2_len = sizeof(ether) m->l3_len = sizeof(ip) m->l4_len = sizeof(udp) m->inner_l2_len = sizeof(ether) + sizeof (vxlan) m->inner_l3_len = sizeof(ip) didier