FreeBSD only use one worker process?

Hello, I am testing Nginx-1.9.3/1.9.6 in FreeBSD 10.2.

I have set worker process 8 (= my cpu core), and then nginx really spawned 8 worker process.
However, nginx only use one worker process while I running apache benchmark and monitoring from top -P.
I observed that the working worker process had higher PRI, but nginx should balance worker loading in my thought.
Is this right in FreeBSD for some reason like its scheduler? or I have setup something wrong in my nginx.conf?

Below is my scratch from ps -aux while apache benchmark testing.

# ps -aux | grep nginx
ray 4870 49.0 0.2 32344 12676 - R 5:43PM 0:39.52 nginx: worker process (nginx)
root 4869 0.0 0.0 24152 3468 - Is 5:43PM 0:00.00 nginx: master process ./sbin/ngi
ray 4871 0.0 0.1 28248 7560 - I 5:43PM 0:00.01 nginx: worker process (nginx)
ray 4872 0.0 0.1 28248 7560 - I 5:43PM 0:00.01 nginx: worker process (nginx)
ray 4873 0.0 0.1 28248 7560 - I 5:43PM 0:00.01 nginx: worker process (nginx)
ray 4874 0.0 0.1 28248 7560 - I 5:43PM 0:00.01 nginx: worker process (nginx)
ray 4875 0.0 0.1 28248 7560 - I 5:43PM 0:00.01 nginx: worker process (nginx)
ray 4876 0.0 0.1 28248 7560 - I 5:43PM 0:00.01 nginx: worker process (nginx)
ray 4877 0.0 0.1 28248 7560 - I 5:43PM 0:00.01 nginx: worker process (nginx)

You can see only one process working.


In addition, I have tested max connections of Nginx to approve this problem.
Generally, max connections of Nginx should be worker process * worker connection, but I could only reached the limit of worker_connections(set =10000) based on nginx http stub status module:

Active connections: 9985
server accepts handled requests
5205900 5205900 5103413
Reading: 0 Writing: 1 Waiting: 9984

Below is my nginx.conf:

user ray;
worker_processes 8;
worker_rlimit_nofile 1000000;
error_log logs/error.log warn;

events {
use kqueue;
accept_mutex off;
worker_connections 10000;
}

http {
include mime.types;
default_type application/octet-stream;

access_log off;
sendfile on;
tcp_nopush on;
keepalive_timeout 65;
keepalive_requests 10000;


gzip on;
open_file_cache max=200000 inactive=20s;
open_file_cache_valid 30s;
open_file_cache_min_uses 2;
open_file_cache_errors on;
server {
listen 80 backlog=4096 reuseport so_keepalive=30::10;
server_name localhost;

#charset koi8-r;

#access_log logs/host.access.log main;

location / {
root /mnt/html;
index index.html index.htm;
}
location /nginx_status {
# Turn on stats
stub_status on;
access_log off;
}

error_page 500 502 503 504 /50x.html;
location = /50x.html {
root /mnt/html;
}
}
}