Re: [Xen-devel] detecting paging inside of VMs

[Keir Fraser <Keir.Fraser@xxxxxxxxxxxx>]

On 21 Jun 2006, at 16:10, Tim Wood wrote:

> I'd like to be able to detect when a VM is pressed for memory without 
> doing anything inside of the VM. 
> My idea is to add some code in the hypervisor that would try to detect 
> paging in each domU, or maybe just monitor the rate at which memory 
> pages are being requested and released.
> I know that the guest OSes are responsible for managing their own page 
> tables, but I suspect that some of this still goes through the VMM.
If you know the domU has a swap partition then you could modify blkback 
driver in dom0 (or pull stats out of it somehow) to detect swap 
activity. Dom0 seems a better probe point than Xen -- it knows about 
I/O and it will also be the place where you implement policy to decide 
who gets what memory.
 -- Keir


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