I believe the only true atomic instructions are CS and CSD. PLO is considered atomic when using the same lock. Concurrency is only guaranteed with some sort of lock which is to expensive to implement for every instruction and for storage being referenced / modified. The odds of a single instruction concurrency issue is extremely low (essentially 0) but still possible. CPU's, storage, and pipelines are exactly the same. Using MVC example, the speed of movement would be exactly the same therefore you should never experience a problem. If on the other hand, there was something to make one MVC operate at a different speed (e.g. pipeline algorithm), then you would have a concurrency issue. Regards, Jon. On Sunday, July 30, 2017 5:50 PM, Phil Smith <[email protected]> wrote: Mmm...I'm pretty sure a single instruction is still atomic. I'm sure Peter Relson or one of the other IBMers will chime in, but it there has to be some sort of interlock at some level. And I've debugged plenty of concurrency problems, never seen a mixture from a single instruction!
...phsiii
