Re: [Xen-users] poor harddisk performance HVM domain (Windows 2003 guest)

[Javier Guerra <javier@xxxxxxxxxxx>]

On Sunday 07 May 2006 8:37 am, Joost van den Broek wrote:
> It even gets worse when installing and using Ubuntu HVM, can't enable DMA
> for the QEMU harddisk, resulting in a very slow +-3.5MB/s read. Isn't there
> any way to resolve this?

qemu's HD emulation is very primitive; no DMA, no LBA48.  but it shouldn't be 
such slow, since the real device (in dom0) does have DMA.  of course, the 
best solution is still in the future, when a HVM domain would accept special 
paravirtualized drivers for HD and network.  those will be needed to get 
better performance for windows.

PD, the newest version of qemu does have both DMA and LBA48, but i think 
nobody has bothered porting it to Xen

-- 
Javier

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