Re: Emacs 32 -> 64 bits on Win32

Re: Emacs 32 -> 64 bits on Win32

[Fabrice Popineau]

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>
> I'm quite sure it is, but I don't have a 64-bit MinGW development
> environment installed to verify that.  I suggest to ask a question on
> emacs-devel@gnu.org.


I installed it and I can confirm it is the same size for int and long.


>  > Although, Emacs tries to virtually allocate a 2Gb heap. What should be
> done
> > on a 64bits machine ?
> > For sure, the heap could grow much further.
>
> How much physical memory would a typical 64-bit Windows box have?  I'd
> say set the reserved heap size to twice that much.  If the page file
> size is something like 1.5 to 2 times the size of physical RAM,
> Windows will probably refuse a larger reservation anyway.
>

No it doesn't.
Well, it was rather the process I find questionable when switching to a
large address space :
start trying to reserve 2Gb (hard coded value) and diminish the size up to
the point where it will fit.

With a 64 bits address space, you can reserve much more, even if after
that, you aren't able
to commit the pages. I have a 4Gb machine and I have been able to reserve
about
540Gb. So the question is : with a 64 bits emacs, where do you start ?
The 2Gb limit was half the address space for 32bits, and it makes sense to
start there.
But with 64bits, the 2Gb are honoured easily and you can even claim for
more.
So where do you start ?

I found this which may be of interest :
http://msdn.microsoft.com/en-us/library/aa384271(v=VS.85).aspx
if we prefer to stick with "small" address space.

Fabrice

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Re: Emacs 32 -> 64 bits on Win32

[Eli Zaretskii]

> From: Fabrice Popineau <fabrice.popineau@gmail.com>
> Date: Sun, 20 Nov 2011 23:16:48 +0100
> 
> > How much physical memory would a typical 64-bit Windows box have?  I'd
> > say set the reserved heap size to twice that much.  If the page file
> > size is something like 1.5 to 2 times the size of physical RAM,
> > Windows will probably refuse a larger reservation anyway.
> >
> 
> No it doesn't.  [...]  I have a 4Gb machine and I have been able to
> reserve about 540Gb. So the question is : with a 64 bits emacs,
> where do you start ?

If you can reserve 1/2 TB, let's start with that.  We can increase it
later if people complain ;-)

> if we prefer to stick with "small" address space.

We don't.  But thanks for the reference.