Re: [PATCH] Add a page cache-backed balloon device driver.

On Wed, 27 Jun 2012 00:41:06 +0300, "Michael S. Tsirkin" [off-list ref] wrote:

On Tue, Jun 26, 2012 at 01:32:58PM -0700, Frank Swiderski wrote:

quoted

This implementation of a virtio balloon driver uses the page cache to
"store" pages that have been released to the host.  The communication
(outside of target counts) is one way--the guest notifies the host when
it adds a page to the page cache, allowing the host to madvise(2) with
MADV_DONTNEED.  Reclaim in the guest is therefore automatic and implicit
(via the regular page reclaim).  This means that inflating the balloon
is similar to the existing balloon mechanism, but the deflate is
different--it re-uses existing Linux kernel functionality to
automatically reclaim.

Signed-off-by: Frank Swiderski <redacted>

I'm pondering this:

Should it really be a separate driver/device ID?
If it behaves the same from host POV, maybe it
should be up to the guest how to inflate/deflate
the balloon internally?

Well, it shouldn't steal ID 10, either way :)  Either use a completely
bogus number, or ask for an id.

But AFAICT this should be a an alternate driver of for the same device:
it's not really a separate device, is it?

Cheers,
Rusty.