Re: GCC 4.8 out of memory

[Frank Wille <frank%phoenix.owl.de@localhost>]

Michael van Elst wrote:

> On Tue, Jun 02, 2015 at 04:16:48PM +0200, Frank Wille wrote:
> > On Mon, 1 Jun 2015 20:28:13 +0200
> > Michael van Elst <mlelstv%serpens.de@localhost> wrote:
> > > It is just a limit. The only constraint is that the text+data+stack
> > > address space must be handled by pmap which is limited to 512MB.
> > 
> > Wasn't that 224MB for 040/060?
>
> that was apparently fixed:
>
> revision 1.41
> date: 2010-12-28 19:31:05 +0100;  author: mhitch;  state: Exp;  lines: +2
-3;
> branches:  1.41.2;  1.41.4;
> Raise address of user stack to the highest safe (for 68040 mmu) address,
> which increases available user address space by 256MB.  One file in
> pkgsrc/lang/php53 was too large for the amiga.  Also remove an old
> presumably outdated comment.

There is still a strange 224MB limit somewhere. The last vmparam.h patch,
which extends MAXDSIZ to 416MB, does not work!

I noticed that programs are now running out of memory after allocating not
much more than 30MB, although I have 128MB RAM and 512MB swap.

So I made a series of tests with kernels having a different MAXDSIZ and
wrote a small test program which tries to allocate as much memory as
possible with malloc(). This is the result:

MAXDSIZ   max. malloc-size
416       63
260       186
256       190
240       206

Seem like the optimal value for MAXDSIZ would be arround 224MB, which gives
a maximum data segment of 224MB.

Can somebody explain that?

-- 
Frank Wille