Re: Spinlock performance improvement proposal

Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us> writes:
> From postmaster startup, by default, could we try larger amounts of
> buffer memory until it fails then back off and allocate that? Seems
> like a nice default to me.

Chewing all available memory is the very opposite of a nice default,
I'd think.

The real problem here is that some platforms will let us have huge shmem
segments, and some will only let us have tiny ones, and neither of those
is a reasonable default behavior. Allowing the platform to determine
our sizing is the wrong way round IMHO; the dbadmin should have a clear
idea of what he's getting, and silent adjustment of the B/N parameters
will not give him that.

regards, tom lane