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

[Wiles, Keith]

Which version of Pktgen? I just pushed a patch in 3.5.3 to fix a  performance problem.

> 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