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Re: semaphore and spin locks

On Sun, Aug 05, 2001 at 11:51:37AM -0400, w.us@verizon.net wrote:
> Spin locks only work in a multiprocessor environment.

Right.  (at least in the Linux kernel..)

> If you use it in a unprocessor environment, then the waiting process would
> keep running in a spin and have no chance to release it and the whole
> kernel would hang.

No.  What waiting processes?

As spinlock are not allowed to be held over a blocking call there is no
way a process holding a spinlock can ever be schedule().  That way _no_
spinlock can be held at all in a UP kernel.

That's why their are optimized away.

	Christoph

-- 
Whip me.  Beat me.  Make me maintain AIX.
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