Re: [Qemu-devel] Anyone seeing huge slowdown launching qemu with Linux 2.6.35?

[Alexander Graf]

On 04.08.2010, at 18:46, Anthony Liguori wrote:

> On 08/04/2010 11:44 AM, Avi Kivity wrote:
>> On 08/04/2010 03:53 PM, Anthony Liguori wrote:
>>> 
>>> So how do we enable support for more than 20 disks?  I think a virtio-scsi 
>>> is inevitable..
>> 
>> Not only for large numbers of disks, also for JBOD performance.  If you have 
>> one queue per disk you'll have low queue depths and high interrupt rates.  
>> Aggregating many spindles into a single queue is important for reducing 
>> overhead.
> 
> Right, the only question is, to you inject your own bus or do you just reuse 
> SCSI.  On the surface, it seems like reusing SCSI has a significant number of 
> advantages.  For instance, without changing the guest's drivers, we can 
> implement PV cdroms or PC tape drivers.

What exactly would keep us from doing that with virtio-blk? I thought that 
supports scsi commands already.


Alex