server {
    listen  80  backlog=1024;
    ...

backlog=number
   sets the backlog parameter in the listen() call that limits the maximum length for the queue of pending connections. By default, backlog is set to -1 on FreeBSD, DragonFly BSD, and macOS, and to 511 on other platforms.

sysctl -w net.core.somaxconn=65535

sysctl -w net.ipv4.ip_local_port_range="1024 65535"

sysctl -w net.ipv4.tcp_tw_reuse=1

sysctl -w fs.file-max=1048576

initContainers:
- name: setsysctl
    image: busybox
    securityContext:
        privileged: true
    command:
    - sh
    - -c
    - |
        sysctl -w net.core.somaxconn=65535
        sysctl -w net.ipv4.ip_local_port_range="1024 65535"
        sysctl -w net.ipv4.tcp_tw_reuse=1
        sysctl -w fs.file-max=1048576

apiVersion: v1
kind: ConfigMap
metadata:
  name: nginx-ingress-controller
# nginx ingress 性能优化: https://www.nginx.com/blog/tuning-nginx/
data:
  # nginx 与 client 保持的一个长连接能处理的请求数量，默认100，高并发场景建议调高。
  # 参考: https://kubernetes.github.io/ingress-nginx/user-guide/nginx-configuration/configmap/#keep-alive-requests
  keep-alive-requests: "10000"
  # nginx 与 upstream 保持长连接的最大空闲连接数 (不是最大连接数)，默认 320，在高并发下场景下调大，避免频繁建联导致 TIME_WAIT 飙升。
  # 参考: https://kubernetes.github.io/ingress-nginx/user-guide/nginx-configuration/configmap/#upstream-keepalive-connections
  upstream-keepalive-connections: "2000"
  # 每个 worker 进程可以打开的最大连接数，默认 16384。
  # 参考: https://kubernetes.github.io/ingress-nginx/user-guide/nginx-configuration/configmap/#max-worker-connections
  max-worker-connections: "65536"