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Date: Fri, 14 Sep 2012 14:24:57 +0200
From: Aurelien Jarno <aurelien@aurel32.net>
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Subject: Re: [Qemu-devel] qemu-system-i386 vs qemu-system-x86_64 ?
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To: Michael Tokarev <mjt@tls.msk.ru>
Cc: Jan Kiszka <jan.kiszka@siemens.com>, qemu-devel <qemu-devel@nongnu.org>

On Fri, Sep 14, 2012 at 02:03:58PM +0400, Michael Tokarev wrote:
> On 14.09.2012 14:00, Jan Kiszka wrote:
> []
> > The major difference in qemu-system-i386 vs. qemu-system-x86_64 is on
> > the TCG side: We measured noticeable performance benefits when running
> > 32/16 bit OSes against qemu-system-i386 vs. using qemu-system-x86_64. I
> > don't have numbers at hand, but colleagues decided to use the 32-bit
> > version for that reason (when no KVM is available).
> 
> Interesting.  Maybe someone should look at the difference on TCG side
> and merge interesting bits from i386 to x86_64... :)

Most of the code between i386 and x86_64 is basically the same. For
improving TCG performances, the only interesting thing to merge from i386 to
x86_64 would be the use 32-bit registers instead of 64-bit registers. Oh
wait...

-- 
Aurelien Jarno                          GPG: 1024D/F1BCDB73
aurelien@aurel32.net                 http://www.aurel32.net