On Wed, 9 May 2012 11:59:17 +0300
Gleb Natapov <[email protected]> wrote:
> Hmm, yes if it is file backed it may work. Setting up qemu to use file
> backed memory is one more complication while running the test though.
> I haven't checked by I am not sure that MADV_DONTNEED will drop page
> immediately though. It probably puts it on some list to be freed later.
> Hmm actually looking at the comments it seems like this is what happens:
>
> /*
> * Application no longer needs these pages. If the pages are dirty,
> * it's OK to just throw them away. The app will be more careful about
> * data it wants to keep. Be sure to free swap resources too. The
> * zap_page_range call sets things up for shrink_active_list to actually
> * free
> * these pages later if no one else has touched them in the meantime,
> * although we could add these pages to a global reuse list for
> * shrink_active_list to pick up before reclaiming other pages.
> */
zap_page_range() actually frees these pages, no?
Virtio balloon seems to rely on this.
Thanks,
Takuya
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