From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Hu, Jiayu" Subject: Re: [PATCH v3 2/5] gso: add TCP/IPv4 GSO support Date: Fri, 15 Sep 2017 07:54:40 +0000 Message-ID: References: <1504598270-60080-1-git-send-email-jiayu.hu@intel.com> <1505184211-36728-1-git-send-email-jiayu.hu@intel.com> <1505184211-36728-3-git-send-email-jiayu.hu@intel.com> <2601191342CEEE43887BDE71AB9772584F249FE8@irsmsx105.ger.corp.intel.com> <20170913104407.GA57844@dpdk15.sh.intel.com> <2601191342CEEE43887BDE71AB9772584F24AACB@irsmsx105.ger.corp.intel.com> <20170914060705.GA60858@dpdk15.sh.intel.com> <2601191342CEEE43887BDE71AB9772584F24ADD2@irsmsx105.ger.corp.intel.com> <2601191342CEEE43887BDE71AB9772584F24AE4D@irsmsx105.ger.corp.intel.com> <2601191342CEEE43887BDE71AB9772584F24B081@irsmsx105.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" Return-path: Received: from mga03.intel.com (mga03.intel.com [134.134.136.65]) by dpdk.org (Postfix) with ESMTP id ECC041041 for ; Fri, 15 Sep 2017 09:54:45 +0200 (CEST) In-Reply-To: <2601191342CEEE43887BDE71AB9772584F24B081@irsmsx105.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" Hi Konstantin, > -----Original Message----- > From: Ananyev, Konstantin > Sent: Friday, September 15, 2017 2:39 AM > To: Kavanagh, Mark B ; Hu, Jiayu > > Cc: dev@dpdk.org; Tan, Jianfeng > Subject: RE: [PATCH v3 2/5] gso: add TCP/IPv4 GSO support >=20 >=20 >=20 > > -----Original Message----- > > From: Kavanagh, Mark B > > Sent: Thursday, September 14, 2017 4:42 PM > > To: Hu, Jiayu ; Ananyev, Konstantin > > > Cc: dev@dpdk.org; Tan, Jianfeng > > Subject: RE: [PATCH v3 2/5] gso: add TCP/IPv4 GSO support > > > > >From: Hu, Jiayu > > >Sent: Thursday, September 14, 2017 11:01 AM > > >To: Ananyev, Konstantin ; Kavanagh, > Mark B > > > > > >Cc: dev@dpdk.org; Tan, Jianfeng > > >Subject: RE: [PATCH v3 2/5] gso: add TCP/IPv4 GSO support > > > > > >Hi Konstantin and Mark, > > > > > >> -----Original Message----- > > >> From: Ananyev, Konstantin > > >> Sent: Thursday, September 14, 2017 5:36 PM > > >> To: Hu, Jiayu > > >> Cc: dev@dpdk.org; Kavanagh, Mark B ; > Tan, > > >> Jianfeng > > >> Subject: RE: [PATCH v3 2/5] gso: add TCP/IPv4 GSO support > > >> > > >> > > >> > > >> > -----Original Message----- > > >> > From: Hu, Jiayu > > >> > Sent: Thursday, September 14, 2017 10:29 AM > > >> > To: Ananyev, Konstantin > > >> > Cc: dev@dpdk.org; Kavanagh, Mark B ; > Tan, > > >> Jianfeng > > >> > Subject: RE: [PATCH v3 2/5] gso: add TCP/IPv4 GSO support > > >> > > > >> > Hi Konstantin, > > >> > > > >> > > -----Original Message----- > > >> > > From: Ananyev, Konstantin > > >> > > Sent: Thursday, September 14, 2017 4:47 PM > > >> > > To: Hu, Jiayu > > >> > > Cc: dev@dpdk.org; Kavanagh, Mark B > ; > > >> Tan, > > >> > > Jianfeng > > >> > > Subject: RE: [PATCH v3 2/5] gso: add TCP/IPv4 GSO support > > >> > > > > >> > > Hi Jiayu, > > >> > > > > >> > > > -----Original Message----- > > >> > > > From: Hu, Jiayu > > >> > > > Sent: Thursday, September 14, 2017 7:07 AM > > >> > > > To: Ananyev, Konstantin > > >> > > > Cc: dev@dpdk.org; Kavanagh, Mark B > ; > > >> Tan, > > >> > > Jianfeng > > >> > > > Subject: Re: [PATCH v3 2/5] gso: add TCP/IPv4 GSO support > > >> > > > > > >> > > > Hi Konstantin, > > >> > > > > > >> > > > On Thu, Sep 14, 2017 at 06:10:37AM +0800, Ananyev, Konstantin > wrote: > > >> > > > > > > >> > > > > Hi Jiayu, > > >> > > > > > > >> > > > > > > > > >> > > > > > > > > >> > > > > > > > -----Original Message----- > > >> > > > > > > > From: Ananyev, Konstantin > > >> > > > > > > > Sent: Tuesday, September 12, 2017 12:18 PM > > >> > > > > > > > To: Hu, Jiayu ; dev@dpdk.org > > >> > > > > > > > Cc: Kavanagh, Mark B ; Tan, > > >> Jianfeng > > >> > > > > >> > > > > > > > Subject: RE: [PATCH v3 2/5] gso: add TCP/IPv4 GSO supp= ort > > >> > > > > > > > > > >> > > > > > > > > result, when all of its GSOed segments are freed, th= e > packet > > >is > > >> > > freed > > >> > > > > > > > > automatically. > > >> > > > > > > > > diff --git a/lib/librte_gso/rte_gso.c > > >b/lib/librte_gso/rte_gso.c > > >> > > > > > > > > index dda50ee..95f6ea6 100644 > > >> > > > > > > > > --- a/lib/librte_gso/rte_gso.c > > >> > > > > > > > > +++ b/lib/librte_gso/rte_gso.c > > >> > > > > > > > > @@ -33,18 +33,53 @@ > > >> > > > > > > > > > > >> > > > > > > > > #include > > >> > > > > > > > > > > >> > > > > > > > > +#include > > >> > > > > > > > > + > > >> > > > > > > > > #include "rte_gso.h" > > >> > > > > > > > > +#include "gso_common.h" > > >> > > > > > > > > +#include "gso_tcp4.h" > > >> > > > > > > > > > > >> > > > > > > > > int > > >> > > > > > > > > rte_gso_segment(struct rte_mbuf *pkt, > > >> > > > > > > > > - struct rte_gso_ctx gso_ctx __rte_unused, > > >> > > > > > > > > + struct rte_gso_ctx gso_ctx, > > >> > > > > > > > > struct rte_mbuf **pkts_out, > > >> > > > > > > > > uint16_t nb_pkts_out) > > >> > > > > > > > > { > > >> > > > > > > > > + struct rte_mempool *direct_pool, *indirect_pool; > > >> > > > > > > > > + struct rte_mbuf *pkt_seg; > > >> > > > > > > > > + uint16_t gso_size; > > >> > > > > > > > > + uint8_t ipid_delta; > > >> > > > > > > > > + int ret =3D 1; > > >> > > > > > > > > + > > >> > > > > > > > > if (pkt =3D=3D NULL || pkts_out =3D=3D NULL || nb_= pkts_out > < 1) > > >> > > > > > > > > return -EINVAL; > > >> > > > > > > > > > > >> > > > > > > > > - pkts_out[0] =3D pkt; > > >> > > > > > > > > + if (gso_ctx.gso_size >=3D pkt->pkt_len || > > >> > > > > > > > > + (pkt->packet_type & > gso_ctx.gso_types) !=3D > > >> > > > > > > > > + pkt->packet_type) { > > >> > > > > > > > > + pkts_out[0] =3D pkt; > > >> > > > > > > > > + return ret; > > >> > > > > > > > > + } > > >> > > > > > > > > + > > >> > > > > > > > > + direct_pool =3D gso_ctx.direct_pool; > > >> > > > > > > > > + indirect_pool =3D gso_ctx.indirect_pool; > > >> > > > > > > > > + gso_size =3D gso_ctx.gso_size; > > >> > > > > > > > > + ipid_delta =3D gso_ctx.ipid_flag =3D=3D > RTE_GSO_IPID_INCREASE; > > >> > > > > > > > > + > > >> > > > > > > > > + if (is_ipv4_tcp(pkt->packet_type)) { > > >> > > > > > > > > > >> > > > > > > > Probably we need here: > > >> > > > > > > > If (is_ipv4_tcp(pkt->packet_type) && (gso_ctx->gso_ty= pes > & > > >> > > DEV_TX_OFFLOAD_TCP_TSO) !=3D 0) {... > > >> > > > > > > > > >> > > > > > > Sorry, actually it probably should be: > > >> > > > > > > If (pkt->ol_flags & (PKT_TX_TCP_SEG | PKT_TX_IPV4) =3D= =3D > > >> PKT_TX_IPV4 > > >> > > && > > >> > > > > > > (gso_ctx->gso_types & DEV_TX_OFFLOAD_TCP_TSO) !=3D= 0) > {... > > >> > > > > > > > >> > > > > > I don't quite understand why the GSO library should be awa= re if > > >the > > >> TSO > > >> > > > > > flag is set or not. Applications can query device TSO capa= bility > > >> before > > >> > > > > > they call the GSO library. Do I misundertsand anything? > > >> > > > > > > > >> > > > > > Additionally, we don't need to check if the packet is a TC= P/IPv4 > > >> packet > > >> > > here? > > >> > > > > > > >> > > > > Well, right now PMD we doesn't rely on ptype to figure out = what > > >type > > >> of > > >> > > packet and > > >> > > > > what TX offload have to be performed. > > >> > > > > Instead it looks at TX part of ol_flags, and > > >> > > > > My thought was that as what we doing is actually TSO in SW, = it > would > > >> be > > >> > > good > > >> > > > > to use the same API here too. > > >> > > > > Also with that approach, by setting ol_flags properly user c= an use > > >the > > >> > > same gso_ctx and still > > >> > > > > specify what segmentation to perform on a per-packet basis. > > >> > > > > > > >> > > > > Alternative way is to rely on ptype to distinguish should > > >segmentation > > >> be > > >> > > performed on that package or not. > > >> > > > > The only advantage I see here is that if someone would like = to > add > > >> GSO > > >> > > for some new protocol, > > >> > > > > he wouldn't need to introduce new TX flag value for > mbuf.ol_flags. > > >> > > > > Though he still would need to update TX_OFFLOAD_* capabiliti= es > and > > >> > > probably packet_type definitions. > > >> > > > > > > >> > > > > So from my perspective first variant (use HW TSO API) is mor= e > > >> plausible. > > >> > > > > Wonder what is your and Mark opinions here? > > >> > > > > > >> > > > In the first choice, you mean: > > >> > > > the GSO library uses gso_ctx->gso_types and mbuf->ol_flags to = call > a > > >> > > specific GSO > > >> > > > segmentation function (e.g. gso_tcp4_segment(), gso_tunnel_xxx= ()) > for > > >> > > each input packet. > > >> > > > Applications should parse the packet type, and set an exactly > correct > > >> > > DEV_TX_OFFLOAD_*_TSO > > >> > > > flag to gso_types and ol_flags according to the packet type. T= hat is, > > >the > > >> > > value of gso_types > > >> > > > is on a per-packet basis. Using gso_ctx->gso_types and mbuf- > >ol_flags > > >> at > > >> > > the same time > > >> > > > is because that DEV_TX_OFFLOAD_*_TSO only tells tunnelling typ= e > and > > >> the > > >> > > inner L4 type, and > > >> > > > we need to know L3 type by ol_flags. With this design, HW > > >> segmentation > > >> > > and SW segmentation > > >> > > > are indeed consistent. > > >> > > > > > >> > > > If I understand it correctly, applications need to set 'ol_fla= gs =3D > > >> > > PKT_TX_IPV4' and > > >> > > > 'gso_types =3D DEV_TX_OFFLOAD_VXLAN_TNL_TSO' for a > > >> > > "ether+ipv4+udp+vxlan+ether+ipv4+ > > >> > > > tcp+payload" packet. But PKT_TX_IPV4 just present the inner L3 > type > > >for > > >> > > tunneled packet. > > >> > > > How about the outer L3 type? Always assume the inner and the > outer L3 > > >> > > type are the same? > > >> > > > > >> > > It think that for that case you'll have to set in ol_flags: > > >> > > > > >> > > PKT_TX_IPV4 | PKT_TX_OUTER_IPV4 | PKT_TX_TUNNEL_VXLAN | > > >> > > PKT_TX_TCP_SEG > > >> > > > >> > OK, so it means PKT_TX_TCP_SEG is also used for tunneled TSO. The > > >> > GSO library doesn't need gso_types anymore. > > >> > > >> You still might need gso_ctx.gso_types to let user limit what types = of > > >> segmentation > > >> that particular gso_ctx supports. > > >> An alternative would be to assume that each gso_ctx supports all > > >> currently implemented segmentations. > > >> This is possible too, but probably not very convenient to the user. > > > > > >Hmm, make sense. > > > > > >One thing to confirm: the value of gso_types should be > DEV_TX_OFFLOAD_*_TSO, > > >or new macros? > > > > Hi Jiayu, Konstantin, > > > > I think that the existing macros are fine, as they provide a consistent= view > of segmentation capabilities to the application/user. >=20 > +1 > I also think it is better to re-use DEV_TX_OFFLOAD_*_TSO. There might be an 'issue', if we use 'PKT_TX_TCP_SEG' to tell the GSO library to segment a packet or not. Given the scenario that an application only wants to do GSO and doesn't want to use TSO. The application sets 'mbuf->ol_flags=3DPKT_TX_TCP_SEG' and doesn't set mbuf->tso_segsz. Then the GSO library segments the packet, and all output GSO segments have the same ol_flags as the input packet (in current GSO library design). Then the output GSO segments are transmitted to rte_eth_tx_prepare(). If the NIC is i40e, its TX prepare fun= ction, i40e_prep_pkts, checks if mbuf->tso_segsz is in the range of I40E_MIN_TSO_M= SS and I40E_MAX_TSO_MSS, when PKT_TX_TCP_SEG is set. So an error happens in this scenario, since tso_segsz is 0. =20 In fact, it may confuse the PMD driver when set PKT_TX_TCP_SEG but don't wa= nt to do TSO. One solution is that the GSO library removes the PKT_TX_TCP_SEG = flag for all GSO segments after finishes segmenting. Wonder you and Mark's opini= on. =20 Thanks, Jiayu >=20 > > > > I was initially concerned that they might be too coarse-grained (i.e. o= nly > IPv4 is currently supported, and not IPv6), but as per Konstantin's > > previous example, the DEV_TX_OFFLOAD_*_TSO macros can be used in > concert with the packet type to determine whether a packet should > > be fragmented or not. > > > > Thanks, > > Mark > > > > > > > >Jiayu > > >> Konstantin > > >> > > >> > > > >> > The first choice makes HW and SW segmentation are totally the same= . > > >> > Applications just need to parse the packet and set proper ol_flags= , and > > >> > the GSO library uses ol_flags to decide which segmentation functio= n to > > >use. > > >> > I think it's better than the second choice which depending on ptyp= e to > > >> > choose segmentation function. > > >> > > > >> > Jiayu > > >> > > > > >> > > Konstantin > > >> > > > > >> > > > > > >> > > > Jiayu > > >> > > > > Konstantin