Re: [Xen-devel] [PATCH 07/10] xen/mmu: Work with 1-1 mappings whenallocating new top/middle entries.

From: Konrad Rzeszutek Wilk
Date: Wed Dec 22 2010 - 12:48:23 EST


On Wed, Dec 22, 2010 at 08:54:31AM +0000, Ian Campbell wrote:
> On Tue, 2010-12-21 at 21:37 +0000, Konrad Rzeszutek Wilk wrote:
> > We were not properly taking under advisement the 1-1 mappings
> > when a large area of memory was ballooned out.
>
> Are we lazily allocating the p2m tree nodes for regions initially
> covered by the balloon? (perhaps we have always done this and it isn't
> new with this series)

Before: Yes
Now: Yes.
>
> Would it be simpley to always populate enough tree nodes to cover the
> ballooned area as well as nr_pages at start of day and therefore avoid
> worrying about it later on (except for memory hotplug which is special
> in this way already)?

Tried that, ran out of reserved_brk space :-) But not sure what
we would gain for this - it is not always guaranteed that we will populate
up to the memory 'maxmem' region.

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