[Qemu-devel] Re: scheduling of qemu threads

[Anthony Liguori]

David S. Ahern wrote:
> Last week or so Anthony made a comment about qemu basically being single
> threaded given its global mutex. What are the impacts to simultaneous
> scheduling of qemu threads? As I understand it, qemu has a main thread,
> a monitor thread, an IO thread and a thread for each vcpu. Can 2 or more
> vcpu threads run concurrently? Can a vcpu thread and an IO thread run
> concurrently? Does kvm alter the concurrency?
>   

All threads run in lock-step except when a VCPU is running (via 
kvm_run).  So a VCPU can run while the IO thread is active.  Only one 
VCPU can execute IO at a given time though.

Regards,

Anthony Liguori

> david
>