Re: [Qemu-devel] [PATCH v2 3/3] virtio-balloon: add a timer to limit the free page report waiting time

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

On 02/27/2018 09:08 PM, Liang Li wrote:
> On Tue, Feb 27, 2018 at 06:10:47PM +0800, Wei Wang wrote:
>> On 02/27/2018 08:50 AM, Michael S. Tsirkin wrote:
>>> On Mon, Feb 26, 2018 at 12:35:31PM +0800, Wei Wang wrote:
>>>> On 02/09/2018 08:15 PM, Dr. David Alan Gilbert wrote:
>>>>> * Wei Wang (wei.w.wang@intel.com) wrote:
>>> I think all this is premature optimization. It is not at all clear that
>>> anything is gained by delaying migration. Just ask for hints and start
>>> sending pages immediately.  If guest tells us a page is free before it's
>>> sent, we can skip sending it.  OTOH if migration is taking less time to
>>> complete than it takes for guest to respond, then we are better off just
>>> ignoring the hint.
>> OK, I'll try to create a thread for the free page optimization. We create
>> the thread to poll for free pages at the beginning of the bulk stage, and
>> stops at the end of bulk stage.
>> There are also comments about postcopy support with this feature, I plan to
>> leave that as the second step (that support seems not urgent for now).
>>
>>
>> Best,
>> Wei
> you can make use the current migration thread instead of creating a new one.
>

This is what this version is doing - we make the optimization 
implementation be part of the migration thread. To make the optimization 
go in parallel with the the migration thread, we need another thread for 
the optimization.

Best,
Wei