Re: [PATCH] PostgreSQL 9.4 mmap(2) performance regression on FreeBSD...

Sean Chittenden <sean@chittenden.org> writes:
> In the same breath, it would also be nice if the following were committed:
> [ use named POSIX semaphores on FreeBSD ]

Really?  Why?  According to the notes in our code, named POSIX semaphores
are the least attractive of the three Unixoid semaphore APIs we support,
because they require eating a file descriptor per backend per
max_connection slot.  That's a lot of FDs in any large configuration.
FreeBSD's support for SysV semaphores would have to be pretty darn awful
to make me think this was a good change, and I've not heard complaints
in that direction before.

If you meant to propose using *unnamed* POSIX semaphores, that might be
a reasonable change, but it would still need some supporting evidence.
        regards, tom lane