[Omp] A question about OpenMP 2.5

[Jakub Jelinek]

On Wed, Mar 21, 2007 at 05:00:29AM -0700, Bronis R. de Supinski wrote:
> Note that it is not clear where to define the hardware
> aromicity level, which is why the specification has tried
> to avoid doing so. I could easily argue that the right
> level of write atomicity for a DSM implementation is at
> the page granularity. While I don't think anyone would
> accept that, it is very unclear where we stop. If Brad's
> example used a char array, does it work? I would hope so...

Not everywhere.  E.g. older Alpha CPUs (without BWX extension, like
ev4, ev45 or ev5) couldn't write 8 and 16-bit quantities atomically, only
32-bit and above, so for 8 and 16-bit accesses it would need to read
old 32-bit word, update the byte in question in it and store it again.

	Jakub