RE: [PATCH v36 0/5] Virtio-balloon: support free page reporting

[Wang, Wei W]

On Friday, July 20, 2018 8:52 PM, Michael S. Tsirkin wrote:
> On Fri, Jul 20, 2018 at 04:33:00PM +0800, Wei Wang wrote:
> > This patch series is separated from the previous "Virtio-balloon
> > Enhancement" series. The new feature,
> VIRTIO_BALLOON_F_FREE_PAGE_HINT,
> > implemented by this series enables the virtio-balloon driver to report
> > hints of guest free pages to the host. It can be used to accelerate
> > live migration of VMs. Here is an introduction of this usage:
> >
> > Live migration needs to transfer the VM's memory from the source
> > machine to the destination round by round. For the 1st round, all the
> > VM's memory is transferred. From the 2nd round, only the pieces of
> > memory that were written by the guest (after the 1st round) are
> > transferred. One method that is popularly used by the hypervisor to
> > track which part of memory is written is to write-protect all the guest
> memory.
> >
> > This feature enables the optimization by skipping the transfer of
> > guest free pages during VM live migration. It is not concerned that
> > the memory pages are used after they are given to the hypervisor as a
> > hint of the free pages, because they will be tracked by the hypervisor
> > and transferred in the subsequent round if they are used and written.
> >
> > * Tests
> > - Test Environment
> >     Host: Intel(R) Xeon(R) CPU E5-2699 v4 @ 2.20GHz
> >     Guest: 8G RAM, 4 vCPU
> >     Migration setup: migrate_set_speed 100G, migrate_set_downtime 2
> > second
> 
> Can we split out patches 1 and 2? They seem appropriate for this release ...

Sounds good to me. I'm not sure if there would be comments on the first 2 patches. If no, can you just take them here? Or you need me to repost them separately?

Best,
Wei