RHEL8 tuned.service는 net.core.somaxconn을 2048로 설정했지만 일부 서비스에서는 작동하지 않음

Issue

• tuned.service는 net.core.somaxconn을 2048로 설정했지만 일부 서비스에서는 작동하지 않습니다.
• tuned.service 및 httpd.service 샘플:

# rpm -q tuned
tuned-2.21.0-1.el8_9.noarch
# rpm -q tuned-2.21.0-1.el8_9.noarch --changelog | grep -B1 1998310
  - throughput-performance: set net.core.somaxconn to at least 2048
    resolves: rhbz#1998310
# systemctl is-active tuned.service 
active
# grep somaxconn -R /lib/tuned/*
/lib/tuned/throughput-performance/tuned.conf:net.core.somaxconn=>2048
# sysctl net.core.somaxconn
net.core.somaxconn = 2048
# systemctl is-active httpd
active
# ss -ltnp sport = :80
State              Recv-Q             Send-Q                         Local Address:Port                          Peer Address:Port             Process             
LISTEN             0                  128                                  0.0.0.0:80                                 0.0.0.0:*                 users:(("httpd",pid=850,fd=3),("httpd",pid=841,fd=3),("httpd",pid=836,fd=3),("httpd",pid=835,fd=3),("httpd",pid=834,fd=3),("httpd",pid=793,fd=3))
# systemctl restart httpd.service 
# ss -ltnp sport = :80
State              Recv-Q             Send-Q                         Local Address:Port                          Peer Address:Port             Process             
LISTEN             0                  511                                  0.0.0.0:80                                 0.0.0.0:*                 users:(("httpd",pid=1708,fd=3),("httpd",pid=1707,fd=3),("httpd",pid=1706,fd=3),("httpd",pid=1705,fd=3),("httpd",pid=1704,fd=3),("httpd",pid=1700,fd=3))

ListenBackLog 의 기본값인 511로 수신 백로그를 설정하려면 httpd.service를 여기에서 다시 시작해야 합니다.

man 2 listen:

The behavior of the backlog argument on TCP sockets changed with Linux 2.2.  Now it specifies the queue length for completely established sockets waiting to be accepted, instead of the number of incomplete connection requests.  The maximum length of the queue for incomplete sockets can be  set  using /proc/sys/net/ipv4/tcp_max_syn_backlog.   When  syncookies  are enabled there is no logical maximum length and this setting is ignored.  See tcp(7) for more information.

/usr/share/doc/kernel-doc-4.18.0-513.5.1.el8_9/Documentation/networking/ip-sysctl.txt:

somaxconn - INTEGER
        Limit of socket listen() backlog, known in userspace as SOMAXCONN.
        Defaults to 128.  See also tcp_max_syn_backlog for additional tuning
        for TCP sockets.