Why is wrk requesting [::] faster than requesting 0.0.0.0? On WSL, localhost.

[4t145]

The service is a simple hyper service returning a short notfound response. Requesting IPv6 is almost four times faster than IPv4.

Requesting ipv6

wrk -t 16 -c 1000 -d 10s http://[::]:9001/index.html
Running 10s test @ http://[::]:9001/index.html
  16 threads and 1000 connections
  Thread Stats   Avg      Stdev     Max   +/- Stdev
    Latency   505.46us  519.50us  17.11ms   92.83%
    Req/Sec    65.02k    46.52k  311.54k    53.49%
  5843961 requests in 10.10s, 0.85GB read
  Socket errors: connect 694, read 0, write 0, timeout 0
  Non-2xx or 3xx responses: 5843961
Requests/sec: 578749.53
Transfer/sec:     86.65MB

Requesting ipv4

wrk -t 16 -c 1000 -d 10s http://0.0.0.0:9001/index.html
Running 10s test @ http://0.0.0.0:9001/index.html
  16 threads and 1000 connections
  Thread Stats   Avg      Stdev     Max   +/- Stdev
    Latency     1.91ms    0.96ms  34.82ms   84.91%
    Req/Sec    18.98k    13.08k   69.15k    59.88%
  1521207 requests in 10.10s, 227.77MB read
  Socket errors: connect 694, read 0, write 0, timeout 0
  Non-2xx or 3xx responses: 1521207
Requests/sec: 150675.57
Transfer/sec:     22.56MB

But why?

My environment:

• linux: Linux beta 5.15.133.1-microsoft-standard-WSL2
• ubuntu version: Ubuntu 22.04.2 LTS
• wsl2 version: 2.0.15.0
• windows version: 10.0.22621.2861
• wsl2 config:

[wsl2]
ipv6=true
memory = 24GB

[experimental]
autoMemoryReclaim=dropcache
networkingMode=mirrored
dnsTunneling=true
firewall=true
autoProxy=true
sparseVhd=true

You can try it your self just using static-web-server, witch is also based on hyper.