why reuseport don't increases throughoutput?

[fengx]

Hello

It shows the new feature reusport from v1.9.1 can increase the QPS by 2-3
times than accept_mutex on and off in this article
https://www.nginx.com/blog/socket-sharding-nginx-release-1-9-1/.  But the
result is disappointed when we have the test in our production with
V1.11.2.2. It don't even have the improvement but reduced, by 10%, dropped
from 42K QPS(with accept_mutex off) to 38K QPS(with reuseport enabled). and
it indeed reduce the latency. The two test cases have anything identicial
except that the later have reuseport enabled.  I wonder if I have missed
some special configuration. 

Thanks.
Xiaofeng

Posted at Nginx Forum: https://forum.nginx.org/read.php?2,274281,274281#msg-274281