Date: Thu, 30 Oct 2008 22:50:22 +0000 From: RW <fbsd06@mlists.homeunix.com> To: freebsd-questions@freebsd.org Cc: stevefranks@ieee.org Subject: Re: kqemu runs 2x faster on i386 than amd64!? Message-ID: <20081030225022.3a6d5b46@gumby.homeunix.com> In-Reply-To: <539c60b90810301508q32d6d920re36177450954e902@mail.gmail.com> References: <539c60b90810301128j2493c4c1wc9519a6fef834490@mail.gmail.com> <539c60b90810301129x58a6e5des56c062ecbb262663@mail.gmail.com> <44iqr9rfz0.fsf@be-well.ilk.org> <539c60b90810301508q32d6d920re36177450954e902@mail.gmail.com>
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On Thu, 30 Oct 2008 15:08:51 -0700 "Steve Franks" <stevefranks@ieee.org> wrote: > > "Steve Franks" <stevefranks@ieee.org> writes: > > > >> Guess I should've mentioned the target is 32-bit win2k... > > > > If the target isn't the same as the host, I think it's going to have > > to use (at least partial) emulation instead of direct execution... > > Yes, but isn't that the same for win2k regardless of wether the host > is fbsdamd64 or fbsdi386? Or are you talking 64 vs. 32 bit? As I understand it, the performance advantage of kqemu over ordinary qemu, comes from running many of the instructions in the emulation directly on the host cpu. An amd64 compatible processor can't run 32-bit code in 64-bit mode and vice-versa, so it's either doing some emulation or switching back and forth between 32/64-bit modes.
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