[dpdk-users] packet drops with missing rxdIdx count in vmxnet3

[Gaurav Bansal <zeebee48@gmail.com>]

hi all,
Tried to debug this further and found that there is a skip in the rxdIdx
count as seen in the logs below. And 'rxdIdx' index is incremented by the
NIC itself. Any ideas on why the 'rxdIdx' count (say 5 as seen below) may
be missing ? Any suggestions to try to find the root cause of missing rx
index ?

PMD: vmxnet3_recv_pkts(): rxd idx: 0 ring idx: 0.
PMD: vmxnet3_recv_pkts(): rxd idx: 1 ring idx: 0.
PMD: vmxnet3_recv_pkts(): rxd idx: 2 ring idx: 0.
PMD: vmxnet3_recv_pkts(): rxd idx: 3 ring idx: 0.
PMD: vmxnet3_recv_pkts(): *rxd idx: 4* ring idx: 0.
PMD: vmxnet3_recv_pkts(): *rxd idx: 6* ring idx: 0.
PMD: vmxnet3_recv_pkts(): rxd idx: 7 ring idx: 0.

thanks,
gaurav

On Thu, Sep 26, 2019 at 1:25 PM Gaurav Bansal <zeebee48@gmail.com> wrote:

> Thanks Stephen for the reply. I am planning to try that but that will
> require some major changes & lot more time, as this library is tightly
> integrated with our code base. Meanwhile please let me know if there is
> anything that can be tried on 16.04 itself.
> thanks,
> gaurav
>
> On Thu, Sep 26, 2019 at 10:46 AM Stephen Hemminger <
> stephen@networkplumber.org> wrote:
>
>> On Thu, 26 Sep 2019 10:45:03 +0530
>> Gaurav Bansal <zeebee48@gmail.com> wrote:
>>
>> > any suggestions here ?
>> >
>> > On Wed, Sep 25, 2019 at 4:09 PM Gaurav Bansal <zeebee48@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.
>>
>