Re: [PATCH v2 1/8] migration: do not wait for free thread

[Xiao Guangrong <guangrong.xiao@gmail.com>]

On 07/24/2018 02:36 AM, Eric Blake wrote:
> On 07/19/2018 07:15 AM, guangrong.xiao@gmail.com wrote:
>> From: Xiao Guangrong <xiaoguangrong@tencent.com>
>>
>> Instead of putting the main thread to sleep state to wait for
>> free compression thread, we can directly post it out as normal
>> page that reduces the latency and uses CPUs more efficiently
>>
>> A parameter, compress-wait-thread, is introduced, it can be
>> enabled if the user really wants the old behavior
>>
>> Signed-off-by: Xiao Guangrong <xiaoguangrong@tencent.com>
>> ---
>>   hmp.c                 |  8 ++++++++
>>   migration/migration.c | 21 +++++++++++++++++++++
>>   migration/migration.h |  1 +
>>   migration/ram.c       | 45 ++++++++++++++++++++++++++-------------------
>>   qapi/migration.json   | 23 ++++++++++++++++++-----
>>   5 files changed, 74 insertions(+), 24 deletions(-)
>>
> 
>> +++ b/qapi/migration.json
>> @@ -462,6 +462,11 @@
>>   # @compress-threads: Set compression thread count to be used in live migration,
>>   #          the compression thread count is an integer between 1 and 255.
>>   #
>> +# @compress-wait-thread: Wait if no thread is free to compress the memory page
>> +#          if it's enabled, otherwise, the page will be posted out immediately
>> +#          in the main thread without compression. It's off on default.
>> +#          (Since: 3.0)
> 
> Is this a bug fix? It's awfully late in the release cycle to be adding new features; is this something that we can live without until 3.1?
> 

It's performance improvement, i think it is not urgent. :)