The maximum is 128 on Linux. The man page mentions that it's only 5 on BSD and some derived systems.
/ Martin Stjernholm, Roxen IS
Previous text:
2003-01-22 10:43: Subject: Re: Stdio.port listen() backlog again...
It it might decrease the load and memory usage on the server a little, which is nice for users that use it for something different than http.
I don't think it matter much, though.
And don't forget that in a traditional unix, it's possible to decrease the backlog below 7, but it's not possible to use a larger backlog; all values for backlog parameter that are larger than seven simply mean seven.
I don't know if that limit is changed in more modern incarnations, but I think the point of using a large value for the backlog parameter is simply to make sure that you use the largest backlog that is supported by the kernel. Which is often 7, or some similarly small number.
/ Niels Möller ()