[dpdk-users] wrong core receive the package

Stephen Hemminger stephen at networkplumber.org
Wed Mar 21 15:48:33 CET 2018

On Wed, 21 Mar 2018 11:13:19 +0800
shengxiao qian <tedsxqian at gmail.com> wrote:

> Hi there;
>     Our machine has 2 cpus(Intel(R) Xeon(R) CPU E5-2630 v4 @ 2.20GHz)with
> 40 cores.
> If the core num is less than or equal to 16. the application with dpdk
> works fine.But if the core num more than 16.there is something wrong with
> it.
>     In our test scenario(more then 16 cores), server a is a tcp client and
> server b is a tcp server. Server a sends a syn packet to server B with
> core1, and server B returns a syn ack message to server a.Although the hash
> value of these two packets is the same, syn ack packets are distributed to
> server a other core(not the send core),Can anyone give some help?

RSS hash is not symmetrical. The SYN and SYN-ACK packets have swapped
address and port (src/dest); therefore the hash will be different.

There are some weaker RSS hash keys that are symmetrical.

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