From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jiayu Hu Subject: Re: [PATCH v3 2/5] gso: add TCP/IPv4 GSO support Date: Thu, 14 Sep 2017 14:07:05 +0800 Message-ID: <20170914060705.GA60858@dpdk15.sh.intel.com> 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> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Cc: "dev@dpdk.org" , "Kavanagh, Mark B" , "Tan, Jianfeng" To: "Ananyev, Konstantin" Return-path: Received: from mga04.intel.com (mga04.intel.com [192.55.52.120]) by dpdk.org (Postfix) with ESMTP id C581D199A9 for ; Thu, 14 Sep 2017 08:04:17 +0200 (CEST) Content-Disposition: inline In-Reply-To: <2601191342CEEE43887BDE71AB9772584F24AACB@irsmsx105.ger.corp.intel.com> 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, 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 support > > > > > > > > > result, when all of its GSOed segments are freed, the 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 = 1; > > > > > + > > > > > if (pkt == NULL || pkts_out == NULL || nb_pkts_out < 1) > > > > > return -EINVAL; > > > > > > > > > > - pkts_out[0] = pkt; > > > > > + if (gso_ctx.gso_size >= pkt->pkt_len || > > > > > + (pkt->packet_type & gso_ctx.gso_types) != > > > > > + pkt->packet_type) { > > > > > + pkts_out[0] = pkt; > > > > > + return ret; > > > > > + } > > > > > + > > > > > + direct_pool = gso_ctx.direct_pool; > > > > > + indirect_pool = gso_ctx.indirect_pool; > > > > > + gso_size = gso_ctx.gso_size; > > > > > + ipid_delta = gso_ctx.ipid_flag == 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_types & DEV_TX_OFFLOAD_TCP_TSO) != 0) {... > > > > > > Sorry, actually it probably should be: > > > If (pkt->ol_flags & (PKT_TX_TCP_SEG | PKT_TX_IPV4) == PKT_TX_IPV4 && > > > (gso_ctx->gso_types & DEV_TX_OFFLOAD_TCP_TSO) != 0) {... > > > > I don't quite understand why the GSO library should be aware if the TSO > > flag is set or not. Applications can query device TSO capability before > > they call the GSO library. Do I misundertsand anything? > > > > Additionally, we don't need to check if the packet is a TCP/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 can 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_* capabilities and probably packet_type definitions. > > So from my perspective first variant (use HW TSO API) is more 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. That 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 type 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_flags = PKT_TX_IPV4' and 'gso_types = 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? Jiayu > Konstantin