On Tue, Oct 28, 2014 at 11:56:15PM +0400, Konstantin Khlebnikov wrote:
> On Tue, Oct 28, 2014 at 9:47 PM, Matt Mullins <mmullins@mmlx.us> wrote:
> > On Sat, Sep 27, 2014 at 11:15:16PM +0400, Konstantin Khlebnikov wrote:
> >> This patch fixes all of them.
> >
> > It seems to have rendered virtio_balloon completely ineffective without
> > CONFIG_COMPACTION and CONFIG_BALLOON_COMPACTION, even for the case that I'm
> > expanding the memory available to my VM.
> 
> What do you mean by ineffective?

Ballooning does not change the amount of memory available at all.  Bisecting
the change got me back to this patch.

I'm currently using 3.18-rc2 and running in qemu-kvm-1.6.2-9.fc20.x86_64 via
libvirt-daemon-1.1.3.6-1.fc20.x86_64.

I'll attach my .config; enabling COMPACTION and BALLOON_COMPACTION makes
virtio-ballooning work again.

> That it cannot handle fragmentation? I saw that without compaction
> ballooning works even better:
> it allocates pages without GFP_MOVABLE and buddy allocator returns
> much less scattered pages.
> 
> >
> > Was this intended?  Should Kconfig be updated so that VIRTIO_BALLOON depends on
> > BALLOON_COMPACTION now?
> 
> Nope, this is independent feature.

Good to know, thanks.