From: Stephen Hemminger <stephen@networkplumber.org> To: "jiangheng (H)" <jiangheng12@huawei.com> Cc: "users@dpdk.org" <users@dpdk.org> Subject: Re: [dpdk-users] DPDK RX TCP checksum failed Date: Sat, 26 Mar 2022 11:59:23 -0700 Message-ID: <20220326115923.715473aa@hermes.local> (raw) In-Reply-To: <cb53d6174669407b96a0f6a09d6bf134@huawei.com> On Sat, 26 Mar 2022 08:13:21 +0000 "jiangheng (H)" <jiangheng12@huawei.com> wrote: > Hi all, > > I tried using the checksum offloads feature in DPDK and it did not see working under virtual machine. > > Port only support TCP checksum and do not support IP checksum: > rx_offload_capa = DEV_RX_OFFLOAD_TCP_CKSUM > tx_offload_capa = DEV_TX_OFFLOAD_TCP_CKSUM > > so I config rxmode.offload txmode.offloads as below: > rxmode.offloads = DEV_RX_OFFLOAD_TCP_CKSUM > txmode.offloads = DEV_TX_OFFLOAD_TCP_CKSUM > > For TX, I set the following parameters, it works good. > mbuf->l2_len = sizeof(*ethhdr) > mbuf->l3_len = ip header len > mbuf-ol_flags = RTE_MBUF_F_TX_IPV4 | RTE_MBUF_F_TX_TCP_CKSUM Virtio does not support IP checksum offload. Because Virtio passes packets to Linux kernel, and Linux kernel does not do IP checksum offload. The IP checksum is so trivial it is faster for most things to just do it in software; the header is only 20 bytes and it will be in cache. You should always check device capability before enabling an offload. > For RX, It will execute the following code: > In drivers/net/virtio/virtio_rxtx.c virtio_rx_offload function : > if (hdr->flags & VIRTIO_NET_HDR_F_NEEDS_CSUM) { > hdrlen = hdr_lens.l2_len + hdr_lens.l3_len + hdr_lens.l4_len; > if (hdr->csum_start <= hdrlen && l4_supported) { > m->ol_flags |= RTE_MBUF_F_RX_L4_CKSUM_NONE; > } else { > > m->ol_flags set to RTE_MBUF_F_RX_L4_CKSUM_NONE, causing the TCP RX checksum failed. > How do I avoid the above code going into this branch? > If you want TCP checksum offload you have to set RTE_ETH_RX_OFFLOAD_TCP_CKSUM in the rxmode when port is configured. This will tell virtio to ask the host to do rx offload. Again, virtio does not do IP checksum offload and you should always query device capability first.
next prev parent reply other threads:[~2022-03-26 18:59 UTC|newest] Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top 2022-03-26 8:13 jiangheng (H) 2022-03-26 18:59 ` Stephen Hemminger [this message] 2022-03-28 1:50 ` 答复: " jiangheng (H) 2022-03-28 2:15 ` Harold Huang 2022-04-07 12:50 ` 答复: " jiangheng (H) 2022-03-28 3:11 ` fwefew 4t4tg 2022-04-07 13:42 ` 答复: " jiangheng (H)
Reply instructions: You may reply publicly to this message via plain-text email using any one of the following methods: * Save the following mbox file, import it into your mail client, and reply-to-all from there: mbox Avoid top-posting and favor interleaved quoting: https://en.wikipedia.org/wiki/Posting_style#Interleaved_style * Reply using the --to, --cc, and --in-reply-to switches of git-send-email(1): git send-email \ --in-reply-to=20220326115923.715473aa@hermes.local \ --to=stephen@networkplumber.org \ --cc=jiangheng12@huawei.com \ --cc=users@dpdk.org \ /path/to/YOUR_REPLY https://kernel.org/pub/software/scm/git/docs/git-send-email.html * If your mail client supports setting the In-Reply-To header via mailto: links, try the mailto: link
DPDK usage discussions This inbox may be cloned and mirrored by anyone: git clone --mirror http://inbox.dpdk.org/users/0 users/git/0.git # If you have public-inbox 1.1+ installed, you may # initialize and index your mirror using the following commands: public-inbox-init -V2 users users/ http://inbox.dpdk.org/users \ users@dpdk.org public-inbox-index users Example config snippet for mirrors. Newsgroup available over NNTP: nntp://inbox.dpdk.org/inbox.dpdk.users AGPL code for this site: git clone https://public-inbox.org/public-inbox.git