[dpdk-users] packet drops seen once the no of rxd pkts reach the ring size

[Gaurav Bansal]

any suggestions here ?

On Wed, Sep 25, 2019 at 4:09 PM Gaurav Bansal <zeebee48 at gmail.com> wrote:

> Hi all,
> I am using dpdk 16.04 library to process the packets on a vmware vm (say
> vm1). The traffic is sent through a client machine using apache bench. I am
> observing an issue when the number of packets reaching the vmxnet3
> interface reaches the descriptor ring size (set to 2048). Till 2048 all the
> packets correctly reach the 'vmxnet3_recv_pkts' function.
>
> But as the number of packets received reaches 2048, i start seeing some
> retransmissions on the client side (as shown by tcpdump on client side).
> Then i captured the packets on the esx host destined to vm1 and it shows
> that all the original packets as well as the corresponding retransmissions
> are reaching vm1. But somehow these packets fail to reach till
> 'vmxnet3_recv_pkts' function (this was found by putting the breakpoint in
> 'vmxnet3_recv_pkts' function and dumping the packet contents, which showed
> that some packets don't reach here).
>
> Now 'vmxnet3_recv_pkts' is the first function which reads the packets from
> the descriptor ring and as the packets are not reaching till here, i am not
> sure on how to debug this further. Possibly some issues related to the ring
> initialization.... I enabled the init & RX logs for vmxnet3, but i don't
> see any error logs as well. I also tried looking at rxq stats and it shows
> 0 all the time :
> (gdb) p rxq->stats
> $1 = {drop_total = 0, drop_err = 0, drop_fcs = 0, rx_buf_alloc_failure = 0}
>
> Can anyone please provide some clues on how to debug this further ? Are
> there any known issues related to this which have been fixed post 16.04
> version ?
> thanks,
> gaurav
>