Re: [PATCH v1 6/6] virtio-balloon: Add support for aerating memory via hinting

Michael S. Tsirkin
2019-07-18T20:38:00Z

On Thu, Jul 18, 2019 at 01:29:14PM -0700, Alexander Duyck wrote:
> So one thing that is still an issue then is that my approach would
> only work on the first migration. The problem is the logic I have
> implemented assumes that once we have hinted on a page we don't need
> to do it again. However in order to support migration you would need
> to reset the hinting entirely and start over again after doing a
> migration.

Well with precopy at least it's simple: just clear the
dirty bit, it won't be sent, and then on destination
you get a zero page and later COW on first write.
Right?

With precopy it is tricker as destination waits until it gets
all of memory. I think we could use some trick to
make source pretend it's a zero page, that is cheap to send.

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MST