[Qemu-devel] The relationship between main thread, monitor thread and migration thread?

[jz4]

Hi,

I am confused about the main thread, monitor thread and migration  
thread. Hope somebody can give me a help.

I observe that when a VM (smp=1, which is a file server) boots up,  
there are two threads for qemu (e.g. i use "top" and "ps" to monitor).  
I think one thread is for the vcpu. The other thread is for the main  
thread. Is the main thread the same as monitor thread? When clients  
connect to the server and start running workload, one more thread is  
generated. I think this one is I/O thread.
Am I right for understanding these 3 threads?

When migration (memory and block) starts , 3 more threads are  
generated. What are those 3 threads? From the code, it seems there is  
no new thread generated for migration. In the mail list, there is a  
series of discussion about whether migration-tcp should be threaded.  
The conclusion is no. Is migration using the same thread as monitor?

Is qemu-kvm or linux kernel responsible for thread scheduling? Does  
KVM has its own algorithm or it only let Linux kernel to handle? If I  
want to understand the thread creation details, where is the code? I  
search in the qemu-git tree and only see the VCPU thread is created in  
qemu-kvm.c. Any other portion that i should look into?

Thanks a lot!

-Jie