Using mmap on MS-Windows

Using mmap on MS-Windows

[Eli Zaretskii]

The MS-Windows build of Emacs currently uses ralloc.c for allocation
of buffer memory, whereas most of the Posix platforms use mmap.  Using
ralloc.c has disadvantages, of which the most important and painful
one is that we must sometimes prevent buffer memory relocation when
xmalloc is called, and ralloc.c is not well equipped for such
situations, which at best leads to loss of free memory (and at worst
causes random crashes).

OTOH, it should be possible to implement mmap on Windows, at least for
the features that Emacs needs, judging by the mmap flags used by
Emacs.

Would someone please volunteer to work on converting the Windows port
to using mmap?  I can point to a couple of existing implementations of
mmap for Windows, which are GPL or PD, and so can be used at least as
starting points.  The goal would be to use mmap instead of ralloc.c
for buffer memory, and switch to the system malloc (instead of using
gmalloc.c) for all the other needs.

TIA

Re: Using mmap on MS-Windows

[Stefan Monnier]

> Would someone please volunteer to work on converting the Windows port
> to using mmap?

That would be welcome, indeed.  Especially, since I think it would let
us get rid of ralloc.c since I don't think it's used on any
other system.


        Stefan

Re: Using mmap on MS-Windows

[Eli Zaretskii]

> From: Stefan Monnier <monnier@IRO.UMontreal.CA>
> Cc: emacs-devel@gnu.org
> Date: Wed, 15 May 2013 15:10:45 -0400
> 
> > Would someone please volunteer to work on converting the Windows port
> > to using mmap?
> 
> That would be welcome, indeed.  Especially, since I think it would let
> us get rid of ralloc.c since I don't think it's used on any
> other system.

It's used on *BSD systems, I think.