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Date: Tue, 03 Aug 2010 23:13:41 +0200
From: Paolo Bonzini <pbonzini@redhat.com>
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Subject: Re: [Qemu-devel] Anyone seeing huge slowdown launching qemu with
	Linux 2.6.35?
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To: Anthony Liguori <anthony@codemonkey.ws>
Cc: qemu-devel@nongnu.org, kvm@vger.kernel.org, "Richard W.M. Jones" <rjones@redhat.com>, Gleb Natapov <gleb@redhat.com>, Avi Kivity <avi@redhat.com>

On 08/03/2010 10:49 PM, Anthony Liguori wrote:
>> On the other hand we end up with stuff like only being able to add 29
>> virtio-blk devices to a single guest.  As best as I can tell, this
>> comes from PCI
>
> No, this comes from us being too clever for our own good and not
> following the way hardware does it.
>
> All modern systems keep disks on their own dedicated bus.  In
> virtio-blk, we have a 1-1 relationship between disks and PCI devices.
> That's a perfect example of what happens when we try to "improve" things.

Comparing (from personal experience) the complexity of the Windows 
drivers for Xen and virtio shows that it's not a bad idea at all.

Paolo