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


Re: [Xen-devel] [PATCH] enforce dom0 cpus and balloon out memory

To: Mark Williamson <mark.williamson@xxxxxxxxxxxx>
Subject: Re: [Xen-devel] [PATCH] enforce dom0 cpus and balloon out memory
From: Ryan Harper <ryanh@xxxxxxxxxx>
Date: Fri, 29 Jul 2005 10:43:24 -0500
Cc: Ian Pratt <m+Ian.Pratt@xxxxxxxxxxxx>, xen-devel@xxxxxxxxxxxxxxxxxxx, Ryan Harper <ryanh@xxxxxxxxxx>
Delivery-date: Fri, 29 Jul 2005 15:41:56 +0000
Envelope-to: www-data@xxxxxxxxxxxxxxxxxxx
In-reply-to: <200507291624.53418.mark.williamson@xxxxxxxxxxxx>
List-help: <mailto:xen-devel-request@lists.xensource.com?subject=help>
List-id: Xen developer discussion <xen-devel.lists.xensource.com>
List-post: <mailto:xen-devel@lists.xensource.com>
List-subscribe: <http://lists.xensource.com/cgi-bin/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=subscribe>
List-unsubscribe: <http://lists.xensource.com/cgi-bin/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=unsubscribe>
References: <9cde8bff05072820043a496e14@xxxxxxxxxxxxxx> <20050729151720.GF8702@xxxxxxxxxx> <200507291624.53418.mark.williamson@xxxxxxxxxxxx>
Sender: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx
User-agent: Mutt/1.5.6+20040907i
* Mark Williamson <mark.williamson@xxxxxxxxxxxx> [2005-07-29 10:25]:
> > You could use vcpu-hotplug to drop the extra cpus from dom0 instead of
> > writing directly into sysfs.  The only stopper to that approach is the
> > fact that dom0's self.channel is not initialized when xend starts and
> > subsequently doesn't send the control message.  Channels are initialized
> > when a domain is built, but since dom0 is built by xen, the routine
> > which sets up channels isn't called for dom0.  Haven't found a good place
> > for xend to initialized the channel for dom0 yet either.
> Hmmm.  Is the channel never set up then?  It'd certainly be nice if it were: 

Correct.  As mentioned above, this is only a problem for dom0 since the
xend contruct_image() code isn't called for dom0 as xen is the builder.
The fix is as simple as calling create_channel() from dom0's XendDomInfo
object.  I've not determined the appropriate location to issue the call.

> then you can use "xm balloon" to set dom0's memory footprint, which is 
> preferable to using the /proc interface directly.

Indeed.  Same goes for using vcpu_hotplug() versus sysfs

Ryan Harper
Software Engineer; Linux Technology Center
IBM Corp., Austin, Tx
(512) 838-9253   T/L: 678-9253

Xen-devel mailing list