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

[Stephen Hemminger]

On Thu, 26 Sep 2019 10:45:03 +0530
Gaurav Bansal <zeebee48 at gmail.com> wrote:

> 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
> >  

Try a newer version of DPDK first.