Re: [PATCH unit-tests] Add async page fault test

[Avi Kivity <avi@redhat.com>]

On 05/09/2012 04:18 PM, Takuya Yoshikawa wrote:
> On Wed, 9 May 2012 11:59:17 +0300
> Gleb Natapov <gleb@redhat.com> 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.
>

The pages are removed from the user address space.  But if they're not
anonymous, the pages still live in the page cache.

-- 
error compiling committee.c: too many arguments to function