Re: A patch for xlog.c

On Sat, 24 Feb 2001, Tom Lane wrote:

> > Forgive me if I posted it to the wrong place -- I was far from
> > proposing this for inclusion.
>
> Diffs posted to pgsql-patches are generally considered to be requests
> for application of a patch.  If this is only an experiment it had best
> be clearly labeled as such.

OK.  Is there are better place for discussion of such?

> > It is but a small step on the way to my plan of mmap()ifying all
> > of the WAL stuff (which may also prove a waste of effort).
>
> Very probably.  What are your grounds for thinking that's a good idea?
> I can't see any reason to think that mmap is more efficient than write
> for simple sequential writes, which is what we need to do.

Potential pros:

a. msync(MS_ASYNC) seems to be exactly
b. Potential to reduce contention
c. Removing syscalls is rarely a bad thing
d. Fewer copies, better cache behaviour

Potential cons:

a. Portability
b. A bad pointer can cause a scribble on the log

Matthew.