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Re: Plans for Linux ELF "i686+" ABI ? Like SPARC V8+ ?
Darryl Miles writes:
> Andrew Haley wrote:
> > This doesn't sound very different from the small memory model. With
> > the small model, the program and its symbols must be linked in the
> > lower 2 GB of the address space, but pointers are still 64 bits. This
> > is the default model for gcc on GNU/Linux. It would be possible in
> > theory to have a `smaller' memory model that only allowed 32-bit
> > pointers, I suppose.
> Small memory model ? I don't understand the point of the "small memory
> model" nor can I substantiate anything you are saying from the
> littlepickcloud, LOL what a domain.
> I'm not aware of a small memory model until now, let alone that I maybe
> actually using it already and that its already what I'm making an
> inquiry about.
Reading the gcc documentation would help you here. Section 3.17.13,
Intel 386 and AMD x86-64 Options.
> > This is amazing! There is no way that going from the ia32 to
> > (presumably) the x86_64 small model should more than double
> > memory consumption. Where has all that memory gone? I think
> > some analysis of memory consumption is needed.
> I presume all the memory is eaten up dealing with 64bit issues both
> Mozilla (using XPCom) and Eclipse (running in a Java JVM) make
> extensive use of pointers. Although Mozilla is a little harder for
> me to measure comparatively but I've never gotten it over 1Gb
> Resident Set Size (with no swap in use).
That's interesting. I certainly have seen some increase in memory
consumption goinf from 32-bit to 64-bit applications on x86_64, but
the fact that in your case it more than doubles is come cause for
concern. Even if pointers were 50% of the allocated memory pool,
which is a pretty extreme assumption, that would only increase memory
use by 50%. In your case, however, memory use has increased by 150%.
This needs explanation.