Re: [Xen-devel] Memory overcommit

[Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>]

Even better, if each domain is only used occasionally, then you could 
save them to disc and restore them on demand. Then they consume no 
memory when not in use. You could combine this with use of the balloon 
driver to implement an allocation policy for in-use domains (as Kip 
suggests) --- e.g., if X domains are active, each gets 1/X of available 
memory.
 -- Keir

On 11 Dec 2005, at 02:00, Kip Macy wrote:

> The balloon driver provides a mechanism for reducing a guest's memory 
> allocation at run-time. At least in principle, it would not be 
> difficult to write a small app that provided policy to slim down idle 
> domUs.
>                  -Kip
>
> On 12/9/05, Tracy R Reed <treed@xxxxxxxxxxxxxxxxxxxxx > wrote:
> > critical) machine for a number of months now. It's looking really 
> > good.
> > One thing that I have not yet seen anyone mention as a feature that I
> > would really like to see is the ability to overcommit memory. I have 
> > 2G
> > of RAM in my machine. I would like to give a developer his own virtual
> > domain to sandbox his application development without having to 
> > dedicate
> > a whole piece of hardware to just him. But I know he won't really log 
> > in
> > and use it all that often. If I give him 512M of my 2G that's 25% of 
> > my
> > memory that will likely be unutilized most of the time. It would be
> > great if I could assign more memory to domains than I actually have 
> > and
> > just let it swap out idle pages. I bet there are a lot of boxes out
> > there, especially in webserver colo's, that really don't get much
> > traffic and really don't need as much RAM as they have in them for
> > normal day to day operations. Just let them swap everything back in 
> > and
> > use up to the maximum RAM configured for that domain if they get busy
> > and need it but let it swap out the rest of the time so other busier
> > domains can use the physical RAM.
> >
> > This is feature #1 on my Xen wishlist. Is there any work going into 
> > this
> > area?
> >
> > --
> > Tracy R Reed
> > http://copilotconsulting.com
> > 1-877-MY-COPILOT
> >
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