On Fri, Oct 16, 2015 at 02:32:15PM +0100, Tom Kiely wrote: > Hi, > I am currently experiencing a serious issue and was hoping someone else > might have encountered it. > > I have a KVM VM using two ixgbe interfaces A and B (configured to use PCI > passthrough) and forwarding traffic from interface A via B. > At about 4 million pps of 64 byte frames, the rx driver > ixgbe_recv_scattered_pkts_vec() appears to be generating mbufs with 2 > segments, the first of which has data_len ==0 and the second data_len==64. > The real problem is that when ixgbe_xmit_pkts() on the tx side gets about 18 > of these packets, it seems to mess up the transmit descriptor handling. > ixgbe_xmit_cleanup() never sees the STAT_DD bit set and no descriptor get > freed leading to total traffic loss. > > I'm still debugging the xmit side to find out what's causing the descriptor > ring problem. > > Has anyone encountered the rx side zero-length-segment issue ? I found a > reference to such an issue on the web but it was years old. > > I'm using DPDK 1.8.0. > > Any information gratefully received, > Tom
Hi Tom, on the TX side, if these two-segment packets are getting sent to the NIC, you probably want to make sure that the TX code is set up to handle multi-segment packets. By default in most drivers, the NO_MULTISEG flag is set on queue initialization. /Bruce
