On Wednesday 24 November 2010 22:25:45 Tom Lane wrote:
> Robert Haas <robertmhaas@gmail.com> writes:
> > On Nov 24, 2010, at 4:05 PM, Andres Freund <andres@anarazel.de> wrote:
> >> Yes, but only once. Also scrubbing a page is faster than copying it...
> >> (and there were patches floating around to do that in advance, not sure
> >> if they got integrated into mainline linux)
> >
> > I'm not following - can you elaborate?
>
> I think Andres is saying that bss space isn't optimized during a fork
> operation: it'll be propagated to the child as copy-on-write pages.
> Dunno if that's true or not, but if it is, it'd be a good reason to
> avoid the scheme you're suggesting.
Afair nearly all pages are propagated with copy-on-write semantics.
Andres