Re: [Qemu-devel] RAM overcomittment

[James Oakley]

On Wednesday 27 September 2006 6:59 pm, The MoonSeeker wrote:
> Le 27 sept. 06 à 23:41, Paul Brook a écrit :
> > qemu is just like any other application. It is only limited by how
> > much
> > virtual memory your OS can provide. ie. if you have sufficient swap
> > you can
> > have as many qemu instances using as much memory as you want.
> >
> > qemu is currently limits each guest to 2Gb ram. This is independent
> > of how
> > much physical memory the host has.
> >
> > Note that modern OS (everything except DOS) generally use all
> > available ram.
> > Telling qemu to use more memory than you have physical ram is
> > liable to cause
> > heavy swapping.
>
> Ok but some virtual solution like openVZ allow you run more VM than
> the memory installed. By example, with openVZ I can create 10 Virtual
> Machine who have a limite fixe to 200 MB but have guaranteed RAM of
> 20MB. With qemu I need to have 10 X 200MB for VM's + 128 MB host of
> RAM installed on the work station...
>
> I think we can Save ressource because in the most case, the VM's will
> never use the 200MB. I think it will be a nice if qemu implemented a
> tool that let use exceed this limitation.

Only Windows guests. The Virtuozzo guys don't advertise the fact that Linux 
*uses all available RAM*.

Overselling RAM for Linux guests as a terrible idea.

-- 
James Oakley
Engineering - SolutionInc Ltd.
address@hidden
http://www.solutioninc.com

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