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Re: [Xen-users] Xen 4 - Page Sharing HowTo?

To: XEN Mailing List <xen-users@xxxxxxxxxxxxxxxxxxx>
Subject: Re: [Xen-users] Xen 4 - Page Sharing HowTo?
From: Andrew Lyon <andrew.lyon@xxxxxxxxx>
Date: Fri, 9 Apr 2010 13:38:12 +0100
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On Fri, Apr 9, 2010 at 1:36 PM, Andrew Lyon <andrew.lyon@xxxxxxxxx> wrote:
> On Fri, Apr 9, 2010 at 1:26 PM, Andrew Lyon <andrew.lyon@xxxxxxxxx> wrote:
>> On Fri, Apr 9, 2010 at 1:18 PM, Andrew Lyon <andrew.lyon@xxxxxxxxx> wrote:
>>> On Thu, Apr 8, 2010 at 11:01 PM, Nick Couchman <Nick.Couchman@xxxxxxxxx> 
>>> wrote:
>>>> One of the features listed as having been added to Xen 4 is page sharing 
>>>> for HVM domUs.  I was wondering if 1) this is automatic, or something that 
>>>> must be enabled, and 2) if it must be enabled, how do you go about 
>>>> enabling it?
>>>>
>>>> Thanks!
>>>> -Nick
>>>
>>> See 
>>> http://lists.xensource.com/archives/html/xen-changelog/2009-12/msg00192.html
>>>
>>> The setting you need to add is memory_sharing
>>>
>>> I think it may require hap but I am not sure yet.. just about to test it.
>>>
>>> Andy
>>>
>>
>> I added memory_sharing=1 to two hvm guests and started them up, xm log
>> shows that the setting was applied but there seems to be no change in
>> the reported memory usage, is there any way to monitor shared memory
>> performance?
>>
>> Andy
>>
>
> I don't think memory_sharing=1 works at all, the very first thing that
> should happen when it is enabled is a printk:
>
> void mem_sharing_init(void)
> {
>    printk("Initing memory sharing.\n");
>
>
> But I've not seen that at all on my 4.x system.
>
> Andy
>

Also the 4.0 release announcement mentioned page to disk, but again I
can find no reference to that... has anybody tested these new
features?

Andy

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