Re: Plans for Linux ELF "i686+" ABI ? Like SPARC V8+ ?

[Andrew Haley <aph-gcc at littlepinkcloud dot COM>]

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.

Andrew.