How to debug receiving error or "rte_eth_stats.ierrors" ...

[Pavel Vazharov]

Glad it helped.

On Thu, Dec 8, 2022 at 11:31 AM Ruslan R. Laishev <zator at yandex.ru> wrote:

> Hello, Paul!
>
> Thanks a lot for u great help!
>
> I did changes in the code as u have advised and 'ierrors' went away!
>
>
> 08.12.2022, 12:17, "Pavel Vazharov" <freakpv at gmail.com>:
>
> Hi,
>
> I see you configure the device so I assume it has the capabilities to do
> the checksum offloading.
>
> However, do you "tell" the device to calculate the checksums for every
> packet. I mean, point 2 from my previous email where certain flags are set
> in the `ol_flags` for every Tx packet.
> I think this is needed in order to tell the device whether you want it to
> calculate the checksum for the given packet or you want it to skip the
> checksum calculation.
> You need something like this for every packet before calling
> `rte_eth_tx_burst` for the packet(s).
>
> pkt->ol_flags |= PKT_TX_IP_CKSUM | PKT_TX_IPV4 | PKT_TX_UDP_CKSUM;
> pkt->l2_len = RTE_ETHER_HDR_LEN;
> pkt->l3_len = <ip header length>; // ((hdr.version_ihl & 0x0F) * 4U);
>
>
> These comments from lib/librte_mbuf/rte_mbuf_core.h explain the flags
> /**
>
>  * Bits 52+53 used for L4 packet type with checksum enabled: 00: Reserved,
>
>  * 01: TCP checksum, 10: SCTP checksum, 11: UDP checksum. To use hardware
>
>  * L4 checksum offload, the user needs to:
>
>  *  - fill l2_len and l3_len in mbuf
>
>  *  - set the flags PKT_TX_TCP_CKSUM, PKT_TX_SCTP_CKSUM or
> PKT_TX_UDP_CKSUM
>  *  - set the flag PKT_TX_IPV4 or PKT_TX_IPV6
>
>  */
> /**
>
>  * Offload the IP checksum in the hardware. The flag PKT_TX_IPV4 should
>
>  * also be set by the application, although a PMD will only check
>
>  * PKT_TX_IP_CKSUM.
>
>  *  - fill the mbuf offload information: l2_len, l3_len
>
>  */
>
> On Thu, Dec 8, 2022 at 10:57 AM Ruslan R. Laishev <zator at yandex.ru> wrote:
>
> Hello, Paul!
>
> Thanks for the answer.
>
>
> I set offloads as follows:
> ...
>
> #define RTE_ETH_TX_OFFLOAD_IPV4_CKSUM       RTE_BIT64(1)
>
> #define RTE_ETH_TX_OFFLOAD_UDP_CKSUM        RTE_BIT64(2)
>
> #define RTE_ETH_TX_OFFLOAD_TCP_CKSUM        RTE_BIT64(3)
>
> ...
>
> *static* uint64_t s_offloads = {
>
> 		RTE_ETH_TX_OFFLOAD_IPV4_CKSUM | RTE_ETH_TX_OFFLOAD_UDP_CKSUM | RTE_ETH_TX_OFFLOAD_TCP_CKSUM};
>
>
>
> 		*if* ( l_dev_info.tx_offload_capa & RTE_ETH_TX_OFFLOAD_MBUF_FAST_FREE )
>
> 			l_port_conf.txmode.offloads |= RTE_ETH_TX_OFFLOAD_MBUF_FAST_FREE;
>
>
>
> 		l_port_conf.txmode.offloads |= s_offloads;
>
>
> l_dev_info.tx_offload_capa = 0x000080bf
> l_port_conf.txmode.offloads = 0x0000000e - it's before rte_eth_dev_configure(
> ( ... &l_port_conf ...)
>
>
>
> The receiver - is  DPDK application. Do I'm need set offloads at receiver
> site to eliminate "ierrors" ?
>
>
>
>
>
> 08.12.2022, 10:54, "Pavel Vazharov" <freakpv at gmail.com>:
>
> Few questions:
> 1. Does the sending NIC support IP and TCP/UDP checksum offloading? I
> mean, if these flags set?
>     struct rte_eth_dev_info dev_info;
>
>     rte_eth_dev_info_get(cfg.nic_port_id_, &dev_info);
>     constexpr auto rxcsum = DEV_RX_OFFLOAD_CHECKSUM;
>
>     constexpr auto l3csum = DEV_TX_OFFLOAD_IPV4_CKSUM;
>
>     constexpr auto l4csum = DEV_TX_OFFLOAD_TCP_CKSUM |
> DEV_TX_OFFLOAD_UDP_CKSUM;
>     dev_rx_csum_          = ((dev_info.tx_offload_capa & rxcsum) ==
> rxcsum);
>     dev_tx_csum_l3_       = ((dev_info.tx_offload_capa & l3csum) ==
> l3csum);
>     dev_tx_csum_l4_       = ((dev_info.tx_offload_capa & l4csum) ==
> l4csum);
>
> 2. Do you "tell" the sending NIC to do the checksum calculations before
> sending the packets? I mean, do you do something like this for outgoing
> packets?
>     if (offl.ip_csum) {
>
>         pkt->ol_flags |= PKT_TX_IP_CKSUM | PKT_TX_IPV4;
>
>         pkt->l2_len = RTE_ETHER_HDR_LEN;
>
>         pkt->l3_len = ih_len;
>
>     }
>
>     if (offl.tcp_csum) {
>
>         pkt->ol_flags |= PKT_TX_TCP_CKSUM;
>
>         pkt->l2_len = RTE_ETHER_HDR_LEN;
>
>         pkt->l3_len = ih_len;
>
>     }
>
>     if (offl.udp_csum) {
>
>         pkt->ol_flags |= PKT_TX_UDP_CKSUM;
>
>         pkt->l2_len = RTE_ETHER_HDR_LEN;
>
>         pkt->l3_len = ih_len;
>
>     }
>
> 3. Is the receiving side also a DPDK application? If it is, and if the NIC
> there supports checksum offloading you can check the flags of the received
> packets to see if the receiving NIC has detected checksum errors.
> pkt->ol_flags & (PKT_RX_IP_CKSUM_BAD | PKT_RX_L4_CKSUM_BAD)
>
> Hope some of the above helps.
>
> On Thu, Dec 8, 2022 at 9:36 AM Ruslan R. Laishev <zator at yandex.ru> wrote:
>
> Hello !
>
> I wrote too small apps to send and receive  ethernet/ip/udp
> frame/packet/dg, so on received side I  see next situation:
> number of in errors is equally a number of received packets. The test
> packet I made manually,  set offloads  IP/UDP checkusm.
> Is there what I'm need to check additionally ?
>
>
>
>
> ---
> С уважением,
> Ruslan R. Laishev
> OpenVMS bigot, natural born system/network progger, C contractor.
> +79013163222
> +79910009922
>
>
>
>
> ---
> С уважением,
> Ruslan R. Laishev
> OpenVMS bigot, natural born system/network progger, C contractor.
> +79013163222
> +79910009922
>
>
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