Re: Balloon driver.

["Cherry G. Mathew" <cherry.g.mathew%gmail.com@localhost>]

Hi Eric,

On 6 July 2010 22:43, Eric Haszlakiewicz <erh%nimenees.com@localhost> wrote:
> On Tue, Jul 06, 2010 at 09:19:57AM +0530, Cherry G. Mathew wrote:
>> On 28 June 2009 19:56, Cherry G. Mathew 
>> <cherry.g.mathew%gmail.com@localhost> wrote:
>> > Hi,
>> >
>> > Quick note to say that I hacked up a little balloon driver from
>> > scratch for fun. It just about works on a XEN3 dom0 but that's it. I'm
>> > posting it here as an FYI as suggested by jym@
>>
>> jym@ and I made a few more changes to this.
>> Have a look here:
>> ftp://ftp.netbsd.org/pub/NetBSD/misc/cherry/balloon/
>>
>> Any feedback would be much appreciated. If things go well, I'm hoping
>> to commit this marked "EXPERIMENTAL" "soon".
>
> A little more verbose comment in the source to explain how this is actually
> used might be nice.  Is there a man page?
>
> I'm guessing this is to implement ballooning as described at:
> http://www.usenix.org/events/osdi02/tech/waldspurger/waldspurger_html/node6.html

That's correct, although this is obviously a Xen specific
implementation. I'll get around to writing a man page for this soon
enough.

This is still experimental, and I don't have any benchmark results.

Briefly, there are two methods to play with this now.

From dom0:

# xm mem-set $domid $newmemsz

or, from within the domU

# sysctl -w kern.xen.balloon.target=$newtargetinpages

kern.xen.balloon.current gives you the current total memory page
reservation of the domU.

Both are equivalent, however, using the sysctl does not reflect in the
dom0 when you use # xm list

I hope this helps.

Cheers,

-- 
~Cherry