Re: HVM disk I/O

[Manuel Bouyer <bouyer%antioche.eu.org@localhost>]

On Thu, Feb 10, 2011 at 12:50:26PM +0100, Tobias Nygren wrote:
> On Thu, 3 Feb 2011 22:14:20 -0800
> "Aaron J. Grier" <agrier%poofygoof.com@localhost> wrote:
> 
> > looking at iostat on the dom0, I see only 8k operations to the RAID.  is
> > this expected?  is xen unable to handle 64k I/O operations through the
> > virtualized hardware?
> 
> i386/conf/XEN3_DOMU has this:
> 
> options     MAXPHYS=32768   #xbd doesn't handle 64k transfers

but this doesn't apply to HVM guests. Also, the dom0 code should be fixed now
(though it stil may be more efficient to limit MAXPHYS to avoid fragmentation,
 I didn't benchmark this)

-- 
Manuel Bouyer <bouyer%antioche.eu.org@localhost>
     NetBSD: 26 ans d'experience feront toujours la difference
--