Hi, > -----Original Message----- > From: users [mailto:[email protected]] On Behalf Of Suchetha p > Sent: Tuesday, June 25, 2019 3:14 PM > To: [email protected] > Subject: [dpdk-users] IPV4 and VLAN RX packets from NIC donot have the mbuf > offload flag set with DPDK 18.08 version > > Hi, > > > After upgrading the DPDK to 18.08 version and RHEL 7.6 OS I observe that > offload flags were not set in the packets received from NIC for eth type > VLAN and IPV4. > > Hence application had to explicitly set the offload flags for VLAN and IPV4 > packet. > > if (ETHER_TYPE_VLAN == eth_type) { > m->ol_flags |= PKT_RX_VLAN_PKT; > > } > if (ETHER_TYPE_IPv4 == eth_type) { > m->ol_flags |= PKT_RX_IPV4_HDR; > }
Do you expect the issue described below is a performance issue from the above code? It seems quite "branchy", meaning branch-misses might have a high performance impact if your incoming traffic is not predictable. From a code point of view, the following achieves the same effect, but without any branching on the datapath; m->ol_flags |= (ETHER_TYPE_VLAN == eth_type) << PKT_RX_VLAN_PKT_SHIFT; Notice that the comparison (ETHER_TYPE_VLAN == eth_type) will result in a 1 or 0, and using |= with a 0 value won't change the m->ol_flags bit contents. If the performance impact of branch-mispredicts is the root cause for your issue, try the above code and see does it help/solve. > If these offload flags were not set in the mbuf the packet would get > dropped and will not be forwarded to the Tap device. > > But the offload flag setting per NIC received packet is causing some > performance issue and delay in data transfer. > > TCP segment loss and retransmissions are observed and TX Tap drops are > observed. > > These changes with respect to offload flag setting for RX VLAN and IPV4 > packet was not required with old DPDK and RHEL6 and packets were getting > forwarded from NIC to Tap device and vice versa without any issue. > > So is anything changed with respect to DPDK and RHEL 7 for ingress packets ? I'll let others reply here - I don't know, sorry. <snip> Hope that helps, -Harry
