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

[Wei Wang <wei.w.wang@intel.com>]

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