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SubjectRE: swap on eMMC and other flash
On Mon, 2 Apr 2012, Luca Porzio (lporzio) wrote:
> Great topics. As per one of Rik original points:
> > 4) skip writeout of zero-filled pages - this can be a big help
> > for KVM virtual machines running Windows, since Windows zeroes
> > out free pages; simply discarding a zero-filled page is not
> > at all simple in the current VM, where we would have to iterate
> > over all the ptes to free the swap entry before being able to
> > free the swap cache page (I am not sure how that locking would
> > even work)
> >
> > with the extra layer of indirection, the locking for this scheme
> > can be trivial - either the faulting process gets the old page,
> > or it gets a new one, either way it'll be zero filled
> >
> Since it's KVMs realm here, can't KSM simply solve the zero-filled pages problem avoiding unnecessary burden for the Swap subsystem?

I would expect that KSM already does largely handle this, yes.
But it's also quite possible that I'm missing Rik's point.


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