qemu on a recent -current, slow like a 486 !

[Doug Kelly]

On Sep 2, 2007, at 10:56 PM, Nenhum_de_Nos wrote:

> hail,
>
> I have a Turion X2 1.8GHz and created a SMP 64bits VM just for running
> folding at home. I'm now compiling linux kernel source for gentoo
> distro, and it takes a century for each module (.o) to be compiled.
>
> FreeBSD xxx.apartnet 7.0-CURRENT FreeBSD 7.0-CURRENT #0: Thu Aug  9
> 01:44:04 BRT 2007     root at xxx.apartnet:/usr/obj/usr/src/sys/xxx  i386
>
> and
>
> QEMU PC emulator version 0.9.0, Copyright (c) 2003-2007 Fabrice  
> Bellard
>
> any more info, just ask ...
>
> is it always this slow ?!

Well, I know -CURRENT's kernel has a ton of debug options enabled by  
default, which will adversely impact performance.  You can disable  
them in the kernel's config file (you'll need to rebuild the kernel,  
though), and the GENERIC config has some notes about them.  Also,  
qemu is a full emulator--although there is a kernel module for Linux  
to allow some type of virtualization, I'm not sure if it's been  
ported to any other OSes.

In short, yes, it will be slow.  I'm sure "a century" is hyperbole,  
but yes, even though you are on a rather fast machine, it will be  
slow, as every single instruction on your qemu VM is going to be  
emulated.

--Doug Kelly