x32 abi support?

[Lennart Poettering]

On Wed, 16.05.12 15:30, Matthew Garrett (mjg59 at srcf.ucam.org) wrote:

Heya,

(added hpa to CC, who appears to be behind x32 upstream)

> On Wed, May 16, 2012 at 04:28:31PM +0200, Lennart Poettering wrote:
> 
> > Mhmm, so I was under the impression that x32 was mostly about increasing
> > the scalability of virtualized systems. i.e. run a higher number of
> > x32 containers/VM on an x86_64 host. Most server software that is run in
> > containers/VMs does not require 64bit address space, and hence using x32
> > for them should be quite benificial so that you can run more
> > containers/VMs per host. After all this would reduce memory and CPU
> > consumption of each, and due to smaller memory usage also result in less
> > IO?
> 
> I was under the impression that it was to make Android work better on 
> Intel. Scalable VMs are an interesting idea, but for a typical session 
> how much RAM are we talking about?

I have no idea. hpa did a talk about it last year at LPC, where the
one line  summary is:

"A work-in-progress new ABI for x86 combines the memory footprint of a
32-bit process with the enhanced capabilities of the x86-64 ISA."

http://www.linuxplumbersconf.org/2011/ocw/sessions/531

I didn't attend the talk, but I figure if hpa claims it lowers memory
footprint (and puts this in the oneline summary) then he has some
statistics and other data to back it up?

Peter, can you give us some background? What's the influence of x32 on
the memory consumption, in comparison to x86_64? Is x32 useful as a
technology to increase scalability on virtualized systems?

Thanks,

Lennart

-- 
Lennart Poettering - Red Hat, Inc.