Re: When should ralloc.c be used?

[Eli Zaretskii]

> Cc: address@hidden, address@hidden
> From: Daniel Colascione <address@hidden>
> Date: Mon, 24 Oct 2016 09:27:43 -0700
> 
> >>> Using mmap has disadvantages: when you need to enlarge buffer text,
> >>> and that fails (because there are no more free pages/addresses after
> >>> the already allocated region), we need to copy buffer text to the new
> >>> allocation.
> 
> 64-bit address spaces are *huge*. What about just making every buffer 
> allocation 2GB long or so, marked PROT_NONE? You don't actually have to 
> commit all that memory --- all you've done is set aside that address 
> space. But because you've set aside so much address space, you'll very 
> likely be able to expand the actual allocation region (a subset of the 
> reserved region) as much as you want.

Sounds OK, although I'm not an expert on that.  But in any case, these
ideas are not baked enough to be applied to the release branch, if we
want to release Emacs 25.2 soon (as in "in a couple of months").

(Of course, there's always the case of a file larger than 2GB, it's
not unheard of, although still quite rare.)