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Re: [Xen-devel] [PATCH] increase initial memory reservation for stubdom

To: Keir Fraser <keir.fraser@xxxxxxxxxxxxx>
Subject: Re: [Xen-devel] [PATCH] increase initial memory reservation for stubdom based HVM domains
From: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
Date: Thu, 15 Jan 2009 17:08:29 +0000
Cc: xen-devel <xen-devel@xxxxxxxxxxxxxxxxxxx>
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Keir Fraser wrote:

> On 15/01/2009 16:46, "Stefano Stabellini" <stefano.stabellini@xxxxxxxxxxxxx>
> wrote:
> 
>> this patch requests 32 additional MB of free RAM from dom0 when an HVM
>> domain is started, if the device model for the domain is provided by a
>> stubdom.
>> This way there is no risk that a stubdom fails to populate the videoram
>> because the RAM freed for the videoram by dom0 has already been used to
>> create the stubdom.
> 
> Does this mean you're giving up on 'properly' fixing the auto ballooner? :-)
> 
> At least the +32 needs a comment. Perhaps abstraction into a function or
> variable as well as a comment. Is the value 32 as arbitrary as it seems?
> 

This fix is not as bad as it seems: I am only increasing the memory
freed by the autoballoner when a stubdom based HVM domain is created, in
order to also take into account the memory used by the stubdom.
In facts 32MB is exactly the size currently needed by a stubdom, it can
probably be reduced, but I preferred making one step at a time.
The memory actually used to create the HVM domain is still the same as
before.


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