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Re: [Qemu-devel] precompiled qemu-system-x86_64 is 32 bit instead of 64b

From: Andrew Warkentin
Subject: Re: [Qemu-devel] precompiled qemu-system-x86_64 is 32 bit instead of 64bit
Date: Thu, 21 Feb 2008 02:07:54 -0700
User-agent: Mozilla Thunderbird 0.8 (X11/20040918)

Laurent Desnogues wrote:

On 2/21/08, Andrew Warkentin <address@hidden> wrote:
Why does it matter if it is 64-bit or not? Most programs at the moment
don't benefit from being compiled 64-bit. I don't get the obsession with
64-bitness that most Linux and BSD people seem to have.

I have programs that run significantly faster when targetting x86_64
(Othello back-end solver, various prime sieves, interpreted simulator,
MAME [cf. http://aarongiles.com/pix/benchmarks.png])., where
significantly means >10%.  I agree I can't qualify my list as "most
programs", but on the other hand I have yet to see one of my
programs running slower as x86_64 bit mode (though I guess some
programs with heavy usage of pointers could be in trouble).

Did anyone compare qemu ia32 vs x86_64?


I guess on x86, there is somewhat of a benefit, because of the extra registers. On any decent architecture, 32- and 64-bit programs would run at the same speed. Still, I don't think that it's worth having separate 32- and 64-bit versions of operating systems over, even on x86.

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