On Tue, 2003-12-16 at 08:14, Phil Payne wrote: > > I imagined that MVC was "atomic" in nature meaning that the second processor > > couldn't > "garble" things until the MVC had run it's course. > > I think that's "implementation-dependent", as IBM would say. Unwise to rely on it.
Phil is right. The path between memory and the processor(s) is a twisty maze of little passages, involving storage alignment, access width, local caches, interleaving, and Bog knows what else. Don't rely on atomic access to *anything* unless the PoOP guarantees it. In olden days before the compare-and-swap instructions we only had test-and-set and spin loops. (And yes, of course, they were coded on punch cards, carried miles to the computer room in four feet of snow, uphill, both ways.) -- David Andrews A. Duda and Sons, Inc. [EMAIL PROTECTED]
