Re: mmap for zeroing WAL log

On Tue, 27 Feb 2001, Tom Lane wrote:

> Matthew Kirkwood <matthew(at)hairy(dot)beasts(dot)org> writes:
> > I had assumed that the overhead would come from synchronous
> > metadata incurring writes of at least the inode, block bitmap
> > and probably an indirect block for each syscall.
>
> No Unix that I've ever heard of forces metadata to disk after each
> "write" call; anyone who tried it would have abysmal performance.
> That's what fsync and the syncer daemon are for.

My understanding was that that's exactly what ffs' synchronous
metadata writes do.

Am I missing something here? Do they jsut schedule I/O, but
return without waiting for its completion?

Matthew.