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] write through or write back?

To: Lei Lu <lulei.wm@xxxxxxxxx>
Subject: Re: [Xen-users] write through or write back?
From: Pasi Kärkkäinen <pasik@xxxxxx>
Date: Tue, 23 Nov 2010 21:23:13 +0200
Cc: xen-users <xen-users@xxxxxxxxxxxxxxxxxxx>
Delivery-date: Tue, 23 Nov 2010 11:30:49 -0800
Envelope-to: www-data@xxxxxxxxxxxxxxxxxxx
In-reply-to: <AANLkTimTzYdLa8sTe06z+Lv6qXawmAuNKr6A+3zUHB_f@xxxxxxxxxxxxxx>
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/mailman/listinfo/xen-users>, <mailto:xen-users-request@lists.xensource.com?subject=subscribe>
List-unsubscribe: <http://lists.xensource.com/mailman/listinfo/xen-users>, <mailto:xen-users-request@lists.xensource.com?subject=unsubscribe>
References: <AANLkTimTzYdLa8sTe06z+Lv6qXawmAuNKr6A+3zUHB_f@xxxxxxxxxxxxxx>
Sender: xen-users-bounces@xxxxxxxxxxxxxxxxxxx
User-agent: Mutt/1.5.18 (2008-05-17)
On Mon, Nov 22, 2010 at 12:18:13PM -0500, Lei Lu wrote:
> Hi everyone,
> 
> Can anybody clarify about what disk cache mechanism the current Xen
> hypervisor use? is it write through or write back? Is there a way to
> change between this two modes? As far as I know, the original linux
> kernel implements the disk cache as page cache and the flusher thread
> may periodically flush the dirty pages to the disk. Does Xen still use
> this strategy by default or not?
> 

Hey,

Actually Xen *hypervisor* itself doesn't affect this..
it depends on your dom0 setup.. ie. what disk backend you 
choose for the guest vm virtual disks.

file: backed disks use dom0 linux kernel caching, 
but tap:aio: or phy: backed disks don't..

-- Pasi


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

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