why nginx just use 511 for listen backlog

[zhijianpeng]

I found that :

#define NGX_LISTEN_BACKLOG 511

and use it as the backlog of  listen()

ls.backlog = NGX_LISTEN_BACKLOG;
 if (listen(s, ls.backlog) == -1) {

Does  it mean that only 511 connection could  be accept at the same time ?
May   I modify it to 1024 or higher( I am sure use it less than  SOMAXCONN )

Posted at Nginx Forum: http://forum.nginx.org/read.php?2,9959,9959#msg-9959