What happened:
Service A with clusterIP 169.169.14.147 and a domain k8s.dev.example.com, the domain resolve to ingress-nginx. Anothor service B will request A, when use domain it works fine. I think using clusterIP directly will get better performance because it saves some time for dns resolve and ingress-nginx proxy, so I change domain to clusterIP. But the result was not expected, it got worse, very low throughput and high latency.

What you expected to happen:
On the above situation, clusterIP should have better performance than ingress-nginx.

How to reproduce it (as minimally and precisely as possible):
ipvs mode, do test with ab

# clusterIP
ab -c100 -t300 -n20000000 -r http://169.169.14.147/

# domain resolve to ingress-nginx
ab -c100 -t300 -n20000000 -r http://k8s.dev.example.com/

Anything else we need to know?:
I install an ipvs enviroment manually and do some test, and found it possiblly because ipvs will use iptables to realize SNAT

Environment:

• Kubernetes version (use kubectl version): 1.11.1
• Cloud provider or hardware configuration:
• OS (e.g. from /etc/os-release): centos 7.2
• Kernel (e.g. uname -a): 3.10
• Install tools: binary
• Others:

/kind bug