Re: [Qemu-devel] RAM overcomittment

[Paul Brook <paul@codesourcery.com>]

> 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...

Nonsense.

> 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.

Like I said, qemu is just like any other application. It's up to your host OS 
to handle management of physical RAM. There's no need for additional tools.

> For my diploma project, I have to create a network simulator but with  
> these limitation I can't use qemu. Because if would like to simulate  
> 20 workstions I need 20 X 128 MB = 2560 MB of RAM... + host RAM!!!  
> But in the simulation, the VM's never will use all of ressource..

Just add a few Gb swap. Even the oldest of machines shouldn't have any problem 
adding say 4Gb swap. Depending on your OS settings you may not even need to 
do that.

Besides which modern entry-level PCs should be able to take 2Gb ram without 
significant problems. Workstations with 8Gb aren't that hard to come by.

Paul