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][PATCH]ioemu:

To: Ian Jackson <Ian.Jackson@xxxxxxxxxxxxx>
Subject: RE: [Xen-devel][PATCH]ioemu:
From: "Zhang, Yang" <yang.zhang@xxxxxxxxx>
Date: Sun, 1 Mar 2009 14:13:45 +0800
Accept-language: en-US
Acceptlanguage: en-US
Cc: "xen-devel@xxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxx>, "keir.fraser@xxxxxxxxxxxxx" <keir.fraser@xxxxxxxxxxxxx>
Delivery-date: Sat, 28 Feb 2009 22:15:42 -0800
Envelope-to: www-data@xxxxxxxxxxxxxxxxxxx
In-reply-to: <18856.9652.22197.350512@xxxxxxxxxxxxxxxxxxxxxxxx>
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/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=subscribe>
List-unsubscribe: <http://lists.xensource.com/mailman/listinfo/xen-devel>, <mailto:xen-devel-request@lists.xensource.com?subject=unsubscribe>
References: <10C63FAD690C13458F0B32BCED571F1406D07CBB@xxxxxxxxxxxxxxxxxxxxxxxxxxxx> <18856.9652.22197.350512@xxxxxxxxxxxxxxxxxxxxxxxx>
Sender: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx
Thread-index: AcmZAphxCZeaFpcsRvKIw2L8LJV8QgBL2lmA
Thread-topic: [Xen-devel][PATCH]ioemu:
>I'm slightly puzzled by this because the effect is to add O_DSYNC to
>the flags passed to open().  But this should effectively be the
>default for us anyway because we implement IDE cache control, which
>defaults to cacheing off.  Does your guest enable the IDE cache ?
I use the default configure to boot my guest. I don't know whether the IDE 
cache is enable default or how to disable it.And i can see that guest boots 
more slowly than before with qcow image when I using the write-through. And I 
see the upstream qemu also has the problem and it has changed to write-back. 
But the code about the cache-mode seems doesn't been executed in qemu-unstable. 

>However I agree that passing BDRV_O_CACHE_WB, to disable O_DSYNC,
>would be correct at least for the non-stubdom case.  Does O_DSYNC even
>have any effect in stubdom ?  I would have expected not.
I doesn't test if it is effect in stubdom. May be you are right. I should not 
change it in stubdom

>Why did you set BDRV_O_RDONLY as well ?  That seems wrong to me.  In
>fact, it worries me that your guest could boot at all with
>BDRV_O_RDONLY forced on.  Also your comment seems somewhat confused;
>the code path your patching is used for all disk opens and not just
>snapshots.
The arg default is zero. And I see the BDRV_O_RDONLY is defined as zero too in 
"block.h". So I think I can change the zero to BDRV_O_RDONLY. There are nothing 
different in essentially. But I think you are right. I should only add the 
BDRV_O_CACHE_WB.



Best Regards
--yang


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

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