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/
Home Products Support Community News


[Xen-users] Xen and distributing memory

To: xen-users@xxxxxxxxxxxxxxxxxxx
Subject: [Xen-users] Xen and distributing memory
From: Marduk <xen@xxxxxxxxxxxxxxxxxxxxxx>
Date: Wed, 21 Feb 2007 11:11:46 -0600
Delivery-date: Wed, 21 Feb 2007 09:11:16 -0800
Envelope-to: www-data@xxxxxxxxxxxxxxxxxx
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>
Sender: xen-users-bounces@xxxxxxxxxxxxxxxxxxx
I'm trying to understand how Xen's memory balloon driver works.  IIRC
VMware's is "dynamic" so if my host has, say, 2 GB memory to spare then
I can still have 3 guests with 1GB of memory assigned each and so long
as all 3 aren't actually *using* all the memory then VMware will
dynamically shuffle the hosts memory around between guests (actually I
think VMware even preserves host swap space for guest RAM so
theoretically they could all could be using 1GB).

>From my understanding with Xen, this is also possible for the most part
but it has to be done manually with 'xm mem-set'.  Is this true?

The reason I am asking is because I have a few domUs that pretty much
run idle except for certain parts of the day.  For example, my backup
server is on a domU.  When it's idle it's only using about 33MB of it's
assigned ram, but once a day when backups are run it uses up to 233MB.
When it's idle I'd like it so the unused RAM is available to other
guests.  Do I have to manually do a 'xm mem-set' and guesstimate how
much memory is going to be used for each guest at certain times of the
day or is there a way that Xen can do this dynamically (a la VMware)?

Xen-users mailing list

<Prev in Thread] Current Thread [Next in Thread>