Re: [RFC] Add support for semaphore-like structure with support for asynchronous I/O

[David Howells]

Benjamin LaHaise <bcrl@xxxxxxxxx> wrote:

> 
> What about the use of atomic operations on frv?  Are they more lightweight 
> than a semaphore, making for a better fastpath?

What do you mean? Atomic ops don't compare to semaphores.

On FRV atomic ops don't disable interrupts; they reserve one of the eight
conditional execution flags at compile time and that flag is cleared by entry
to an exception, thus aborting the write instruction. See:

	Documentation/fujitsu/frv/atomic-ops.txt

I could try and improve the fastpath on the semaphores for FRV - and perhaps
should - but I implemented the semaphores before I'd thought of the clever way
to do atomic ops.

David
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