Re: [Qemu-devel] About the Thread model in Qemu【 Is it one thread per vcpu?】

[解壁伟 <xiebiwei@ict.ac.cn>]

I read the article again, and I get the answer to my question in that 
paragraph.
Thank you very much.
As you've said, TCG's not thread-safe.
Is it only the shared data structure(e.g TB) that prevent TCG to be 
thread-safe? I'm seeking a method to parallize TCG in order to parallize 
Qemu.

And,how do the multi-thread in kvm mode Qemu synchronize to each other? 
For some threads maybe excute faster or slower than others, how do they 
synchronize the clock with each other? Using a huge lock or a global clock?

I'll be appreciate if you can give me some hints for further exploration.

For now, I need a emulator to emulate more cores efficiently.I want to 
analyze whether Qemu can be faster when it emulate more cores, while 
parallelism maybe a good choice.


puck




于 2013/3/13 16:45, Stefan Hajnoczi 写道:
> On Tue, Mar 12, 2013 at 05:34:24PM +0800, 解壁伟 wrote:
>> Hi there:
>>
>> I've read this an article discribe the thread model in Qemu.
>> http://blog.vmsplice.net/2011/03/qemu-internals-overall-architecture-and.html
>> Is there really one thread per vcpu in qemu?
>>
>> When I run the qemu using "-smp 16", I can see only two threads using
>> "ps -xH".
> "Note that TCG is not thread-safe so even under the iothread model it
> multiplexes vcpus across a single QEMU thread. Only KVM can take
> advantage of per-vcpu threads."
>
> If you do not have -enable-kvm then you're probably using TCG.
>
> Stefan
>