[dpdk-users] MLX ConnectX-4 Discarding packets

[Filip Janiszewski]

I wanted just to add, while running the same exact testpmd on the other
machine I won't get a single miss with the same patter traffic:

.
testpmd> stop
Telling cores to stop...
Waiting for lcores to finish...

  ------- Forward Stats for RX Port= 0/Queue= 0 -> TX Port= 0/Queue= 0
-------
  RX-packets: 61711939       TX-packets: 0              TX-dropped: 0


  ------- Forward Stats for RX Port= 0/Queue= 1 -> TX Port= 0/Queue= 1
-------
  RX-packets: 62889424       TX-packets: 0              TX-dropped: 0


  ------- Forward Stats for RX Port= 0/Queue= 2 -> TX Port= 0/Queue= 2
-------
  RX-packets: 61914199       TX-packets: 0              TX-dropped: 0


  ------- Forward Stats for RX Port= 0/Queue= 3 -> TX Port= 0/Queue= 3
-------
  RX-packets: 63484438       TX-packets: 0              TX-dropped: 0


  ---------------------- Forward statistics for port 0
----------------------
  RX-packets: 250000000      RX-dropped: 0             RX-total: 250000000
  TX-packets: 0              TX-dropped: 0             TX-total: 0

----------------------------------------------------------------------------

  +++++++++++++++ Accumulated forward statistics for all
ports+++++++++++++++
  RX-packets: 250000000      RX-dropped: 0             RX-total: 250000000
  TX-packets: 0              TX-dropped: 0             TX-total: 0

++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++++
.

In the lab I've the EPYC connected directly to the Xeon using a 100GbE
link, both same RHL8.4 and same DPDK 21.02, running:

.
./dpdk-testpmd -l 21-31 -n 8 -w 81:00.1  -- -i --rxq=4 --txq=4
--burst=64 --forward-mode=rxonly --rss-ip --total-num-mbufs=4194304
--nb-cores=4
.

and sending from the other end with pktgen, the EPYC loss tons of
packets (see my previous email), the Xeon don't loss anything.

*Confusion!*

Il 9/11/21 4:19 PM, Filip Janiszewski ha scritto:
> Thanks,
> 
> I knew that document and we've implemented many of those settings/rules,
> but perhaps there's one crucial I've forgot? Wonder which one.
> 
> Anyway, increasing the amount of queues impinge the performance, while
> sending 250M packets over a 100GbE link to an Intel 810-cqda2 NIC
> mounted on the EPYC Milan server, i see:
> 
> .
> 1 queue, 30Gbps, ~45Mpps, 64B frame = imiss: 54,590,111
> 2 queue, 30Gbps, ~45Mpps, 64B frame = imiss: 79,394,138
> 4 queue, 30Gbps, ~45Mpps, 64B frame = imiss: 87,414,030
> .
> 
> With DPDK 21.02 on RHL8.4. I can't observe this situation while
> capturing from my Intel server where increasing the queues leads to
> better performance (while with the test input set I drop with one queue,
> I do not drop anymore with 2 on the Intel server.)
> 
> A customer with a brand new EPYC Milan server in his lab observed as
> well this scenario which is a bit of a worry, but again it might be some
> config/compilation issue we need do deal with?
> 
> BTW, the same issue can be reproduced with testpmd, using 4 queues and
> the same input data set (250M of 64bytes frame at 30Gbps):
> 
> .
> testpmd> stop
> Telling cores to stop...
> Waiting for lcores to finish...
> 
>   ------- Forward Stats for RX Port= 0/Queue= 0 -> TX Port= 0/Queue= 0
> -------
>   RX-packets: 41762999       TX-packets: 0              TX-dropped: 0
> 
> 
>   ------- Forward Stats for RX Port= 0/Queue= 1 -> TX Port= 0/Queue= 1
> -------
>   RX-packets: 40152306       TX-packets: 0              TX-dropped: 0
> 
> 
>   ------- Forward Stats for RX Port= 0/Queue= 2 -> TX Port= 0/Queue= 2
> -------
>   RX-packets: 41153402       TX-packets: 0              TX-dropped: 0
> 
> 
>   ------- Forward Stats for RX Port= 0/Queue= 3 -> TX Port= 0/Queue= 3
> -------
>   RX-packets: 38341370       TX-packets: 0              TX-dropped: 0
> 
> 
>   ---------------------- Forward statistics for port 0
> ----------------------
>   RX-packets: 161410077      RX-dropped: 88589923      RX-total: 250000000
>   TX-packets: 0              TX-dropped: 0             TX-total: 0
> 
> ----------------------------------------------------------------------------
> .
> 
> .
> testpmd> show port xstats 0
> ###### NIC extended statistics for port 0
> rx_good_packets: 161410081
> tx_good_packets: 0
> rx_good_bytes: 9684605284
> tx_good_bytes: 0
> rx_missed_errors: 88589923
> .
> 
> Can't figure out what's wrong here..
> 
> 
> Il 9/11/21 12:20 PM, Steffen Weise ha scritto:
>> Hi Filip,
>>
>> i have not seen the same issues.
>> Are you aware of this tuning guide? I applied it and had no issues with
>> intel 100G NIC.
>>
>> HPC Tuning Guide for AMD EPYC Processors
>> http://developer.amd.com/wp-content/resources/56420.pdf
>> <http://developer.amd.com/wp-content/resources/56420.pdf>
>>
>> Hope it helps.
>>
>> Cheers,
>> Steffen Weise
>>
>>
>>> Am 11.09.2021 um 10:56 schrieb Filip Janiszewski
>>> <contact at filipjaniszewski.com>:
>>>
>>> I ran more tests,
>>>
>>> This AMD server is a bit confusing, I can tune it to capture 28Mpps (64
>>> bytes frame) from one single core, so I would assume that using one more
>>> core will at least increase a bit the capture capabilities, but it's
>>> not, 1% more speed and it drops regardless of how many queues are
>>> configured - I've not observed this situation on the Intel server, where
>>> adding more queues/cores scale to higher throughput.
>>>
>>> This issue have been verified now with both Mellanox and Intel (810
>>> series, 100GbE) NICs.
>>>
>>> Anybody encountered anything similar?
>>>
>>> Thanks
>>>
>>> Il 9/10/21 3:34 PM, Filip Janiszewski ha scritto:
>>>> Hi,
>>>>
>>>> I've switched a 100Gbe MLX ConnectX-4 card from an Intel Xeon server to
>>>> an AMD EPYC server (running 75F3 CPU, 256GiB of RAM and PCIe4 lanes),
>>>> and using the same capture software we can't get any faster than 10Gbps,
>>>> when exceeding that speed regardless of the amount of queues configured
>>>> the rx_discards_phy counter starts to raise and packets are lost in huge
>>>> amounts.
>>>>
>>>> On the Xeon machine, I was able to get easily to 50Gbps with 4 queues.
>>>>
>>>> Is there any specific DPDK configuration that we might want to setup for
>>>> those AMD servers? The software is DPDK based so I wonder if some build
>>>> option is missing somewhere.
>>>>
>>>> What else I might want to look for to investigate this issue?
>>>>
>>>> Thanks
>>>>
>>>
>>> -- 
>>> BR, Filip
>>> +48 666 369 823
> 

-- 
BR, Filip
+48 666 369 823