On Fri, Oct 12, 2018 at 10:41:33AM -0700, Richard Henderson wrote: > On 10/11/18 8:24 PM, David Gibson wrote: > > When the balloon is inflated, we discard memory place in it using madvise() > > with MADV_DONTNEED. And when we deflate it we use MADV_WILLNEED, which > > sounds like it makes sense but is actually unnecessary. > > > > The misleadingly named MADV_DONTNEED just discards the memory in question, > > it doesn't set any persistent state on it in-kernel; all that's necessary > > to bring the memory back is to touch it. > > Isn't the point of deflate to free up host memory, for use by other guests or > whatever?
As Eric notes, I think you have inflate and deflate the wrong way around.
> If you do nothing upon deflate, then that doesn't actually happen. It seems
> to
> me that this is backward and you should use DONTNEED on deflate and then
> inflate should do nothing.
>
>
> r~
>
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
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