Re: [Qemu-devel] [PATCH v2 0/3] virtio-balloon: free page hint reporting support

[Wei Wang]

On 02/07/2018 08:02 AM, Michael S. Tsirkin wrote:
> On Tue, Feb 06, 2018 at 07:08:16PM +0800, Wei Wang wrote:
> > This is the deivce part implementation to add a new feature,
> > VIRTIO_BALLOON_F_FREE_PAGE_HINT to the virtio-balloon device. The device
> > receives the guest free page hints from the driver and clears the
> > corresponding bits in the dirty bitmap, so that those free pages are
> > not transferred by the migration thread to the destination.
> >
> > Please see the driver patch link for test results:
> > https://lkml.org/lkml/2018/2/4/60
> >
> > ChangeLog:
> > v1->v2:
> >      1) virtio-balloon
> >          - use subsections to save free_page_report_cmd_id;
> >          - poll the free page vq after sending a cmd id to the driver;
> >          - change the free page vq size to VIRTQUEUE_MAX_SIZE;
> >          - virtio_balloon_poll_free_page_hints: handle the corner case
> >            that the free page block reported from the driver may cross
> >            the RAMBlock boundary.
> >      2) migration/ram.c
> >          - use balloon_free_page_poll to start the optimization
> >
> > Wei Wang (3):
> >    virtio-balloon: VIRTIO_BALLOON_F_FREE_PAGE_HINT
> >    migration: use the free page reporting feature from balloon
> >    virtio-balloon: add a timer to limit the free page report waiting time
> This feature needs in-tree documentation about possible ways to use it,
> tradeoffs involved etc.

OK. I plan to add the documentation in later versions after we mostly 
finalize the QEMU part design.

Best,
Wei