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Re: [Xen-devel] Xen Memory de-duplication

On Thu, Apr 21, 2016 at 9:13 AM, Maryam Masoudian <maryammasoudian@xxxxxxxxx> wrote:

On Thu, Apr 21, 2016 at 5:17 PM, Dario Faggioli <dario.faggioli@xxxxxxxxxx> wrote:
On Wed, 2016-04-20 at 13:01 -0600, Tamas K Lengyel wrote:
> On Apr 20, 2016 12:34, "Dario Faggioli" <dario.faggioli@xxxxxxxxxx>
> wrote:
> > On Wed, 2016-04-20 at 10:25 -0600, Tamas K Lengyel wrote:
> > > On Wed, Apr 20, 2016 at 7:24 AM, Wei Liu <wei.liu2@xxxxxxxxxx>
> wrote:
> > > > Not sure. You can check xl manpage for those commands.
> > > xl doesn't have any command that shows you a breakdown of sharing
> > > among VMs,

Well, I didn't find any useful description for xl sharing : it just shows the shared memory.
What I really want is seeing the deduplicated memory among VMs.
I ran two windows VMs and thought of the kernel memory to be shared among them if the memory de-duplication is enabled in Xen.
But the result of xl sharing for these VMs was 0 .

Xen won't magically share memory across VMs for you, you need to decide what pages want to share and among what VMs. Take a look at https://github.com/tklengyel/drakvuf/blob/master/src/xen_helper/xen_helper.c#L197 for an example on how you can dedup the entire memory of two identical VMs. And as I already mentioned, you can see memory shared across VMs by using the libxc library, as you can see at https://github.com/tklengyel/drakvuf/blob/master/src/xen_helper/xen_helper.c#L245.


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