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-devel

Re: [Xen-devel] questions about ballooning

To: "Daniel Stodden" <stodden@xxxxxxxxxx>
Subject: Re: [Xen-devel] questions about ballooning
From: weiming <zephyr.zhao@xxxxxxxxx>
Date: Sun, 4 Nov 2007 10:37:14 -0500
Cc: Steve Kemp <steve@xxxxxxxxxxxx>, Xen Developers <xen-devel@xxxxxxxxxxxxxxxxxxx>
Delivery-date: Sun, 04 Nov 2007 07:38:09 -0800
Dkim-signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=beta; h=domainkey-signature:received:received:message-id:date:from:to:subject:cc:in-reply-to:mime-version:content-type:references; bh=GPa8gawQCF0bwnGoNQ5UU8B5+jMhg92hT0n1q6LSMYc=; b=F/s1z6a1A6zJ8DOLdxAU2STJhnlq0g4T3wOLG47njiU343yEYAhkkefJXjYpDGSMO7j8tc1obsN2rrOsoz3YHYtkjx1OqE2gJiOGf9UQoYTRLOgYnKpxF/Ffu9BCT92JEn5Pmm286eaOc3eDFcJaEH3uX/l6G1NtnJ9fzwNIjjI=
Domainkey-signature: a=rsa-sha1; c=nofws; d=gmail.com; s=beta; h=received:message-id:date:from:to:subject:cc:in-reply-to:mime-version:content-type:references; b=aSuoiWgctXLEQIK1BDpVCEX2o5oVlCVsefiV6jyHxjBbEb7zLRDziUNfgENqR2dPcEVGQqVd5TkwsoYCxHyDB9sKMluJAJPR5G4dYLdKokfoq2nPEtRzblFuLU+apAaWuQy3o/BF9FPq0XpsdjfqhvO2I7iIUDrnP50E7YD5zGk=
Envelope-to: www-data@xxxxxxxxxxxxxxxxxx
In-reply-to: <1194190202.15096.16.camel@xxxxxxxxxxxxxxxxxxxx>
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: <add59a3f0711031831x71006b1cl190aacd57156133b@xxxxxxxxxxxxxx> <1194187887.15096.1.camel@xxxxxxxxxxxxxxxxxxxx> <20071104150432.GA20812@xxxxxxxxxxxx> <1194190202.15096.16.camel@xxxxxxxxxxxxxxxxxxxx>
Sender: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx
Thanks, Daniel. You answered my first question perfectly that I just post 2 minutes ago. :D

On 11/4/07, Daniel Stodden < stodden@xxxxxxxxxx> wrote:

On Sun, 2007-11-04 at 15:04 +0000, Steve Kemp wrote:
> I have been confused about ballooning on dom0 for a while, so
>  this looks like a good time to ask it.
>
>   I have dom0 with ~1Gb of memory.  (About 900Mb as shown in 'xm list'
>  once it is freshly booted.)
>
>   I start a guest, and that gets decreased as the memory is allocated
>  to domU:
>
>  Name                                        ID   Mem
>  Domain-0                                     0   735
>  etch32-builder.my.flat                      24   128
>
>   After a while I shutdown that guest and I expect the memory to
>  be available to dom0 again - but it never is.  I see dom0 left
>  with the reduced ~700Mb.
>
>   Is that expected?

a leak of that size would not go unnoticed :)

outline, but no warranties, as i didn't build it:

- in the beginng, .. well, all memory belongs to xen.

- dom0, unless otherwise configured (mem=), gets a map of up to the
  whole amount of memory. so anything beyond the VMM can be in dom0.

- lacking any other domain beyond dom0 on boot, the initial reservation
  of dom0 is filled with all pages beyond the VMM allocation. 900MB.

- creating a domU requires dom0 to return part of its
  reservation (decrease_reservation()). 128MB.

- destroying domU is up to the VMM. these pages are not automagically
  reclaimed by dom0. there is also to 'pushing' of pages in a domain,
  as there is no point in doing so. dom0 needs to ask (via
  increase_reservation()).

- dom0, rather idle, is as happy with 735MB as it used to be with
  900MB.
  so the freed domU memory stays on the xen heap for the time being.

regards,
daniel



--
Daniel Stodden
LRR     -      Lehrstuhl für Rechnertechnik und Rechnerorganisation
Institut für Informatik der TU München             D-85748 Garching
http://www.lrr.in.tum.de/~stodden         mailto:stodden@xxxxxxxxxx
PGP Fingerprint: F5A4 1575 4C56 E26A 0B33  3D80 457E 82AE B0D8 735B



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

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