WARNING - OLD ARCHIVES

This is an archived copy of the Xen.org mailing list, which we have preserved to ensure that existing links to archives are not broken. The live archive, which contains the latest emails, can be found at http://lists.xen.org/
   
 
 
Xen 
 
Home Products Support Community News
 
   
 

xen-users

Re: [Xen-users] Disable memory balloon in dom0

To: xen-users@xxxxxxxxxxxxxxxxxxx
Subject: Re: [Xen-users] Disable memory balloon in dom0
From: Mark Williamson <mark.williamson@xxxxxxxxxxxx>
Date: Thu, 8 May 2008 21:20:18 +0100
Cc: Nick Anderson <nick@xxxxxxxxxxxx>
Delivery-date: Thu, 08 May 2008 14:10:14 -0700
Envelope-to: www-data@xxxxxxxxxxxxxxxxxx
In-reply-to: <4821A886.3070101@xxxxxxxxxxxx>
List-help: <mailto:xen-users-request@lists.xensource.com?subject=help>
List-id: Xen user discussion <xen-users.lists.xensource.com>
List-post: <mailto:xen-users@lists.xensource.com>
List-subscribe: <http://lists.xensource.com/cgi-bin/mailman/listinfo/xen-users>, <mailto:xen-users-request@lists.xensource.com?subject=subscribe>
List-unsubscribe: <http://lists.xensource.com/cgi-bin/mailman/listinfo/xen-users>, <mailto:xen-users-request@lists.xensource.com?subject=unsubscribe>
References: <4820C835.40107@xxxxxxxxxxxx> <VA.000031d8.001c8545@xxxxxxxxxxxxxxxxxx> <4821A886.3070101@xxxxxxxxxxxx>
Sender: xen-users-bounces@xxxxxxxxxxxxxxxxxxx
User-agent: KMail/1.8.2
> So I take that to mean setting dom0-min-mem to 0 disables memory
> ballooning(for dom0). I just want to clarify if that is the way to
> disable memory ballooning from dom0. I had been told in ##xen that
> booting with dom0_mem=X effectively disables ballooning.

I'm not sure that dom0_mem=X will disable ballooning completely on it's own; 
I'd expect that Xend will still autoballoon dom0 in order to make space for 
new domUs, if the dom0-min-mem setting allows it to.  So you should disable 
autoballooning even when using dom0_mem=X if you want it not to happen.

> Or is all of this mute if I never allocate more memory that what I have
> in the physical machine total?

If your domU's memory allocations can be satisfied without ballooning dom0 
then I believe it won't get ballooned.  I'd still advise explicitly disabling 
it if you really want it not to happen (and I've been in the habit of 
recommending this as a good practice for a server, since you don't need 
autoballooning there, typically).  This ensures a "safety catch" that 
prevents dom0 accidentally getting shrunk if you start more domUs than 
expected without thinking about the available memory.

Cheers,
Mark

_______________________________________________
Xen-users mailing list
Xen-users@xxxxxxxxxxxxxxxxxxx
http://lists.xensource.com/xen-users