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] HVM domain with write caching going on somewhere to disk

To: "Keir Fraser" <Keir.Fraser@xxxxxxxxxxxx>, <xen-devel@xxxxxxxxxxxxxxxxxxx>
Subject: RE: [Xen-devel] HVM domain with write caching going on somewhere to disk
From: "James Harper" <james.harper@xxxxxxxxxxxxxxxx>
Date: Thu, 8 Nov 2007 22:08:47 +1100
Delivery-date: Thu, 08 Nov 2007 03:09:21 -0800
Envelope-to: www-data@xxxxxxxxxxxxxxxxxx
In-reply-to: <C3589DD0.1818F%Keir.Fraser@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: <AEC6C66638C05B468B556EA548C1A77D01249E62@trantor> <C3589DD0.1818F%Keir.Fraser@xxxxxxxxxxxx>
Sender: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx
Thread-index: Acgh89hmOjf1UcT/R7S91fG2xpfbEgAAJyu6AAAMH9AAAKHtpAAACubg
Thread-topic: [Xen-devel] HVM domain with write caching going on somewhere to disk
> > Hmmm... shouldn't the DomU->qemu->device and
DomU->blkbackend->device
> > path's both have visibility to the same buffer cache though?
> 
> No, it's trickier than that. Blkback sends I/O requests direct into
the
> block subsystem, bypassing the buffer cache. You can see there's
potential
> for confusion therefore!

Ah yes. That would probably do it. So I need to make sure that the
buffer cache is flushed (eg async writes in qemu?)... or maybe get qemu
to talk direct to the block subsystem in the same way... any
suggestions? I've already butchered ioemu to get this working so far
(changed the PCI ID's of the IDE interface so Windows won't detect it)
so I'm not afraid of doing more of it :)

Thanks

James

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