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From: Torbjorn Granlund <tg@gmplib.org>
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Date: Wed, 28 Sep 2011 02:25:43 +0200
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Subject: [Qemu-devel] Qemu varying performance
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To: qemu-devel@nongnu.org

Running Debian's vmlinux-2.6.32-5-4kc-malta under qemu-system-mips works
very well--the system is fast, and when it is idle the qemu-system-mips
process on the host system consumes insignificant CPU.  (The same is
true for qemu-system-mipsel, using the correesponding 'el' Debian
kernel.)

But running Debian's 64-bit kernel vmlinux-2.6.32-5-5kc-malta under
qemu-system-mips64 consumes 100% on the host system, whether the guest
is idle or busy.  (And for qemu-system-mips64el, the same is true for the
corresponding 64-bit el kernel.)

This cpu usage makes it somewhat inconvenient to let the qemu processes
stay running.  Is there anything that can be done about the cpu usage?
Is it a Linux problem (say, that the 64-bit kernel fails to invoke some
clever system sleep instruction when in the idle loop), or is it a qemu
problem?

Another issue I ran into what the sh4 qemu performance.  It is much
worse than other qemu ports (except perhaps ppc64).  What is the reason
behind that?  (The idle thing works well for sh4, though.)

My host system runs FreeBSD 8.2.  The Debian installs all use 6.0.2.

--=20
Torbj=F6rn