[dpdk-dev] IXGBE throughput loss with 4+ cores

Saber Rezvani irsaber at zoho.com
Tue Aug 28 21:16:34 CEST 2018



On 08/28/2018 11:39 PM, Wiles, Keith wrote:
> Which version of Pktgen? I just pushed a patch in 3.5.3 to fix a  performance problem.
I use Pktgen verion 3.0.0, indeed it is O.k as far as I  have one core. 
(10 Gb/s) but when I increase the number of core (one core per queue) 
then I loose some performance (roughly 8.5 Gb/s for 8-core). In my 
scenario Pktgen shows it is generating at line rate, but receiving 8.5 Gb/s.
Is it because of Pktgen???
>
>> On Aug 28, 2018, at 12:05 PM, Saber Rezvani <irsaber at zoho.com> wrote:
>>
>>
>>
>> On 08/28/2018 08:31 PM, Stephen Hemminger wrote:
>>> On Tue, 28 Aug 2018 17:34:27 +0430
>>> Saber Rezvani <irsaber at zoho.com> wrote:
>>>
>>>> Hi,
>>>>
>>>>
>>>> I have run multi_process/symmetric_mp example in DPDK example directory.
>>>> For a one process its throughput is line rate but as I increase the
>>>> number of cores I see decrease in throughput. For example, If the number
>>>> of queues set to 4 and each queue assigns to a single core, then the
>>>> throughput will be something about 9.4. if 8 queues, then throughput
>>>> will be 8.5.
>>>>
>>>> I have read the following, but it was not convincing.
>>>>
>>>> http://mails.dpdk.org/archives/dev/2015-October/024960.html
>>>>
>>>>
>>>> I am eagerly looking forward to hearing from you, all.
>>>>
>>>>
>>>> Best wishes,
>>>>
>>>> Saber
>>>>
>>>>
>>> Not completely surprising. If you have more cores than packet line rate
>>> then the number of packets returned for each call to rx_burst will be less.
>>> With large number of cores, most of the time will be spent doing reads of
>>> PCI registers for no packets!
>> Indeed pktgen says it is generating traffic at line rate, but receiving less than 10 Gb/s. So, it that case there should be something that causes the reduction in throughput :(
>>
>>
> Regards,
> Keith
>





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