Re: [Qemu-devel] [question] Is there a plan to introduce a unified co-scheduling mechanism to CFS ?

[Zhang Haoyu]

>> Hi,
>>
>> Is it worthy to introduce a unified co-scheduling mechanism to CFS ?
>> Because multiple cooperating threads or tasks frequently synchronize 
with each other,
>> not executing them concurrently would only increase the latency of 
synchronization.
>> For example, a thread blocking in spinlock to waiting for another 
thread to release the same spinlock
>> might reduce its waiting time by being executed concurrently with 
the thread which hold the same spinlock.
>> In virtualization scenario, multiple vcpus (which belong to the same 
vm) co-scheduling is more desired
>> when several cooperating threads/task is running in guest.
>>
>> Is there a plane for this work?
>
> Please refer to gang scheduler.
>
Is there a mechanism to dynamically detect which vcpus belong to the 
same gang?
Maybe a cooperative degree can be used to decide the threshold of which 
vcpus belong to the same gang, just a wild thought.

> Regards,
> Wanpeng Li
>>
>> Thanks,
>> Zhang Haoyu