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

[Xen-users] Re: Memory resizing

To: Anthony Liguori <aliguori@xxxxxxxxxx>
Subject: [Xen-users] Re: Memory resizing
From: Jiri Denemark <jirka@xxxxxxxxxxx>
Date: Sat, 7 Oct 2006 12:03:22 +0200
Cc: xen-users@xxxxxxxxxxxxxxxxxxx
Delivery-date: Sat, 07 Oct 2006 03:04:16 -0700
Envelope-to: www-data@xxxxxxxxxxxxxxxxxx
In-reply-to: <4526CB49.80803@xxxxxxxxxx>
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: <20061006093403.GA7141@xxxxxxxx> <4526CB49.80803@xxxxxxxxxx>
Sender: xen-users-bounces@xxxxxxxxxxxxxxxxxxx
User-agent: Mutt/1.5.11
Thanks for explaining how the balloon driver actually works.

> What's really going on here, is that you create a domain with 7800MB, and
> then the balloon driver tells the kernel that it's allocated (7800-160)MBs.
> The kernel really doesn't know that the balloon driver gave that memory back
> to Xen--it just thinks it's a greedy kernel module.
So the kernel still has 7800MB of memory, (7800-160)MBs eaten up by balloon
driver and 160MBs available to userspace, right? In that case, it seems it's
rather an issue of VM subsystem in Linux.

It's strange the kernel is not willing to swap out a process and kills it even
if there is enough free swap space. But I guess that's somehow connected with
those (7800-160)MBs "held" by ballon driver which kernel cannot swap out.
Anyway it would be nice if the kernel could behave in exactly the same way
regardless of whether a domain is started with limited memory or its memory is
ballooned down.

I wonder if playing with altering kernel's swappiness would help in that... I
tried to make 8GB swap but that didn't help much.

Jirka

-- 
The reason computer chips are so small is computers don't eat much.

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

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