Re: [Qemu-devel] [PATCH -V3 09/32] virtio-9p: Implement P9_TWRITE/ Thread model in QEMU

[Avi Kivity <avi@redhat.com>]

On 04/01/2010 04:14 PM, Paul Brook wrote:
>
>>> On a philosophical note, threads may be easier to model complex
>>> hardware that includes a processor, for example our scsi card (and how
>>> about using tcg as a jit to boost it :)
>>>        
>> Yeah, it's hard to argue that script evaluation shouldn't be done in a
>> thread.  But that doesn't prevent me from being very cautious about how
>> and where we use threading :-)
>>      
> I agree that making script execution asynchronous is a good thing, however I'm
> not convinced that (3) is the best way to do this. It's certainly the most
> flexible model, however it also places responsibility for locking/correctness
> on the device developer.
>
> A more limited scheme (e.g. asynchronous callbacks) can actually be
> significant advantage. By forcing the developer to solve the problem in a
> particular way we significantly reduce the scope for race conditions, and
> hopefully restrict all locking concerns to common code/APIs.
>    

Can you elaborate?  When would the callbacks be called?  When would the 
callbacks yield back?

If the script isn't run to completion (a halt instruction), there isn't 
really a good answer to these questions.

> [1] This issue may come from accidental misuse of terminology, but it's an
> important distinction.
>    

Missing reference to footnote.

-- 
error compiling committee.c: too many arguments to function