[dpdk-dev] Rx-errors with testpmd (only 75% line rate)

Jun Han junhanece at gmail.com
Mon Feb 10 18:34:47 CET 2014

Hi Michael,

We are also trying to purchase an IXIA traffic generator. Could you let us
know which chassis + load modules you are using so we can use that as a
reference to look for the model we need? There seems to be quite a number
of different models.

Thank you.

On Tue, Jan 28, 2014 at 9:31 AM, Dmitry Vyal <dmitryvyal at gmail.com> wrote:

> On 01/28/2014 12:00 AM, Michael Quicquaro wrote:
>> Dmitry,
>> I cannot thank you enough for this information.  This too was my main
>> problem.  I put a "small" unmeasured delay before the call to
>> rte_eth_rx_burst() and suddenly it starts returning bursts of 512 packets
>> vs. 4!!
>> Best Regards,
>> Mike
> Thanks for confirming my guesses! By the way, make sure the number of
> packets you receive in a single burst is less than configured queue size.
> Or you will lose packets too. Maybe your "small" delay in not so small :)
> For my own purposes I use a delay of about 150usecs.
> P.S. I wonder why this issue is not mentioned in documentation. Is it
> evident for everyone doing network programming?
>> On Wed, Jan 22, 2014 at 9:52 AM, Dmitry Vyal <dmitryvyal at gmail.com<mailto:
>> dmitryvyal at gmail.com>> wrote:
>>     Hello MIchael,
>>     I suggest you to check average burst sizes on receive queues.
>>     Looks like I stumbled upon a similar issue several times. If you
>>     are calling rte_eth_rx_burst too frequently, NIC begins losing
>>     packets no matter how many CPU horse power you have (more you
>>     have, more it loses, actually). In my case this situation occured
>>     when average burst size is less than 20 packets or so. I'm not
>>     sure what's the reason for this behavior, but I observed it on
>>     several applications on Intel 82599 10Gb cards.
>>     Regards, Dmitry
>>     On 01/09/2014 11:28 PM, Michael Quicquaro wrote:
>>         Hello,
>>         My hardware is a Dell PowerEdge R820:
>>         4x Intel Xeon E5-4620 2.20GHz 8 core
>>         16GB RDIMM 1333 MHz Dual Rank, x4 - Quantity 16
>>         Intel X520 DP 10Gb DA/SFP+
>>         So in summary 32 cores @ 2.20GHz and 256GB RAM
>>         ... plenty of horsepower.
>>         I've reserved 16 1GB Hugepages
>>         I am configuring only one interface and using testpmd in
>>         rx_only mode to
>>         first see if I can receive at line rate.
>>         I am generating traffic on a different system which is running
>>         the netmap
>>         pkt-gen program - generating 64 byte packets at close to line
>>         rate.
>>         I am only able to receive approx. 75% of line rate and I see
>>         the Rx-errors
>>         in the port stats going up proportionally.
>>         I have verified that all receive queues are being used, but
>>         strangely
>>         enough, it doesn't matter how many queues more than 2 that I
>>         use, the
>>         throughput is the same.  I have verified with 'mpstat -P ALL'
>>         that all
>>         specified cores are used.  The utilization of each core is
>>         only roughly 25%.
>>         Here is my command line:
>>         testpmd -c 0xffffffff -n 4 -- --nb-ports=1 --coremask=0xfffffffe
>>         --nb-cores=8 --rxd=2048 --txd=2048 --mbcache=512 --burst=512
>>         --rxq=8
>>         --txq=8 --interactive
>>         What can I do to trace down this problem?  It seems very
>>         similar to a
>>         thread on this list back in May titled "Best example for showing
>>         throughput?" where no resolution was ever mentioned in the thread.
>>         Thanks for any help.
>>         - Michael

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