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Re: [Xen-devel] balloon.py unaware of pages on page_scrub_list

To: "Keir Fraser" <Keir.Fraser@xxxxxxxxxxxx>
Subject: Re: [Xen-devel] balloon.py unaware of pages on page_scrub_list
From: "Charles Coffing" <ccoffing@xxxxxxxxxx>
Date: Fri, 23 Jun 2006 12:51:26 -0600
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Keir,

Attached is a patch that makes the ballooning logic in xend aware of
pages that are on the page scrub list.  This fixes the case where
crashing/restarting a domain can cause dom0 to balloon more than
necessary.

I changed the physinfo dictionary in Python to be in KiB, rather than
MiB, to avoid accumulating ugly rounding errors.  I tried to avoid
changing units anywhere else.

The patch is against xen-unstable.  It applies and works against
xen-3.0-testing also (in fact that's where I did most of my testing) but
I don't know if you want to apply it there.  I changed the dom0_physinfo
in a non-backwards-compatible way.  Looked nicer to me to group the
*_pages fields together, but that's probably not something you'd want to
do in 3.0.2...  your call.

Thanks,
Charles

Signed-off-by: Charles Coffing <ccoffing@xxxxxxxxxx>


On Tue, Jun 20, 2006 at  1:20 AM, Keir Fraser
<Keir.Fraser@xxxxxxxxxxxx> wrote: 
> On 19 Jun 2006, at 23:15, Charles Coffing wrote:
> 
>> Would it make sense to give this information to balloon.py, and
apply 
>> some heuristics?  Perhaps xend should wait for the scrub list to go
to 
>> zero before trying to balloon.  Or maybe it should consider that 
>> memory as free, and only try to balloon (needed -  to_scrub).
>>
>> The most obvious way (to me) to get that information to xend is via

>> DOM0_PHYSINFO.  That way, the number of free pages and the number of

>> pages to scrub can be gotten atomically.
>>
>> Thoughts?
>>
>> I volunteer to code and test this if there's some agreement on how
it 
>> should be done.
> 
> Your approach sounds fine to me.
> 
>   --  Keir
> 
> 
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Attachment: xen-scrub-pages.diff
Description: Binary data

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