From mboxrd@z Thu Jan  1 00:00:00 1970
From: Olaf Hering <olaf@aepfle.de>
Subject: Re: [PATCH v3 3/3] tools/libxc: use superpages during
 restore of HVM guest
Date: Fri, 25 Aug 2017 16:00:15 +0200
Message-ID: <20170825140015.GO6372@aepfle.de>
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To: Wei Liu <wei.liu2@citrix.com>
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On Fri, Aug 25, Wei Liu wrote:

> Maybe a middle ground is to scan the batch to see if pfns can be fit
> into a whole super page? I don't think you can get a batch as big as 1G
> but there should be a lot of 2M batches?

I think with the new check of max_pages an overallocation can not happen
anymore. If at some point the domU still has room for a superpage, it
will be allocated. In case the batch does not fully fill the superpage,
the holes will be freed. In the next batch no superpage can be allocated
anymore, but single pages will be used.

This punching of holes might be inefficent, the win is the usage of
superpages in case of contiguous pfns.

Olaf

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