From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Ananyev, Konstantin" Subject: Re: [PATCH 2/5] gso/lib: add TCP/IPv4 GSO support Date: Wed, 30 Aug 2017 09:59:15 +0000 Message-ID: <2601191342CEEE43887BDE71AB9772584F23E1D4@IRSMSX103.ger.corp.intel.com> References: <1503584144-63181-1-git-send-email-jiayu.hu@intel.com> <1503584144-63181-3-git-send-email-jiayu.hu@intel.com> <2601191342CEEE43887BDE71AB9772584F23E097@IRSMSX103.ger.corp.intel.com> <20170830025550.GA113170@dpdk15.sh.intel.com> <2601191342CEEE43887BDE71AB9772584F23E197@IRSMSX103.ger.corp.intel.com> Mime-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: quoted-printable Cc: "dev@dpdk.org" , "Tan, Jianfeng" To: "Ananyev, Konstantin" , "Kavanagh, Mark B" , "Hu, Jiayu" Return-path: Received: from mga04.intel.com (mga04.intel.com [192.55.52.120]) by dpdk.org (Postfix) with ESMTP id 878ED11D4 for ; Wed, 30 Aug 2017 11:59:19 +0200 (CEST) In-Reply-To: <2601191342CEEE43887BDE71AB9772584F23E197@IRSMSX103.ger.corp.intel.com> Content-Language: en-US List-Id: DPDK patches and discussions List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Errors-To: dev-bounces@dpdk.org Sender: "dev" > -----Original Message----- > From: dev [mailto:dev-bounces@dpdk.org] On Behalf Of Ananyev, Konstantin > Sent: Wednesday, August 30, 2017 10:39 AM > To: Kavanagh, Mark B ; Hu, Jiayu > Cc: dev@dpdk.org; Tan, Jianfeng > Subject: Re: [dpdk-dev] [PATCH 2/5] gso/lib: add TCP/IPv4 GSO support >=20 > Hi Mark, >=20 > > >> > + > > >> > +void > > >> > +gso_parse_packet(struct rte_mbuf *pkt) > > >> > > >> There is a function rte_net_get_ptype() that supposed to provide sim= ilar > > >functionality. > > >> So we probably don't need to create a new SW parse function here, in= stead > > >would be better > > >> to reuse (and update if needed) an existing one. > > >> Again user already might have l2/l3/l4.../_len and packet_type setup= ed. > > >> So better to keep SW packet parsing out of scope of that library. > > > > > >Hmm, I know we have discussed this design choice in the GRO library, a= nd I > > >also think it's > > >better to reuse these values. > > > > > >But from the perspective of OVS, it may add extra overhead, since OVS = doesn't > > >parse every > > >packet originally. Maybe @Mark can give us more inputs from the view o= f OVS. > > > > Hi Jiayu, Konstantin > > > > For GSO, the application needs to know: > > - the packet type (as it only currently supports TCP/IPv4, VxLAN, GRE p= ackets) > > - the l2/3/4_lens, etc. (in order to replicate the original packet's he= aders across outgoing segments) > > > > For this, we can use the rte_net_get_ptype function, as per Konstantin'= s suggestion, as it provides both - thanks Konstantin! > > > > WRT the extra overhead in OvS: TSO is the defacto standard, and GSO is = provided purely as a fallback option. As such, and since the > > additional packet parsing is a necessity in order to facilitate GSO, th= e additional overhead is IMO acceptable. >=20 > As I remember, for TSO in DPDK user still have to provide l2/l3/l4_len an= d mss information to the PMD. > So unless user knows these value straightway (user creates a packet himse= lf) some packet processing will be unavailable anyway. > Konstantin s/unavailable/unavoidable/ sorry for bad typing. Konstantin > > > > Thanks, > > Mark > >