RE: [Xen-devel] poor domU VBD performance.

["Ian Pratt" <m+Ian.Pratt@xxxxxxxxxxxx>]

> I found out that dom0 does file-system IO and raw IO ( using 
> dd as a tool to test
> throughput from the disk ) is about exactly the same as when 
> using a standard 
> linux kernel without XEN. But the raw IO from DomU to an 
> unused disk ( a second
> disk in the system ) is limited to fourty percent of the 
> speed I get within Dom0.

Just to be clear: you're doing a dd performance test within dom0 to the
exact same partition on the 2nd disk that you're using when you start
the domU and finding that the domU 'dd' performance is 40% of the dom0
performance?

I've not heard of anyone else having problems like this. What happens if
you use a partition on the 1st disk?

What chipset is the IDE controller? What device (e.g. sda1) are you
exporting the disk partition into the domU as?

Are you sure dom 0 is idle when doing the dd test in the domU?

Ian


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