Re: [Qemu-devel] [PATCH 07/12] qemu-thread: add QemuSemaphore

[Jan Kiszka]

On 2012-07-16 15:20, Paolo Bonzini wrote:
> Il 16/07/2012 14:00, Jan Kiszka ha scritto:
>> On 2012-07-16 12:42, Paolo Bonzini wrote:
>>> The new thread pool will use semaphores instead of condition
>>> variables, because QemuCond does not have qemu_cond_timedwait.
>>
>> I'll post an updated patch (according to last round's review comments)
>> that adds this service for POSIX. I bet you'll find a way to extend it
>> to Win32 if that is required. ;)
> 
> I can do that (or just use pthreads-win32), but only at the cost of
> making cond_wait() slower and more complex.

Why will it affect cond_wait? WaitForSingleObject can time out as well.

> 
>>> (I also like it more this way, since semaphores model well the
>>> producer-consumer problem).
>>
>> Let's not introduce another synchronization mechanism unless there is a
>> real need. Semaphores tend to be misused for things they don't fit, so
>> better keep them out of reach.
> 
> That's what patch review is for...

But even better is avoiding the temptation.

Jan

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