On 7/30/17, Phil Smith <[email protected]> wrote: > Charles Mills wrote, in part: >>The effect of multiple CPUs on a multi-task program is even worse than the >>load, add, store example above. With two CPUs, it is possible for even >>single machine instructions to interleave. So if one task executes MVC >>FOO,=C'Now is the time for all good men to come to the aid of the party' >> and >>another CPU executes MVC FOO,=C'The quick brown fox jumps over the lazy >> dog' >>it is at least in theory* possible for FOO to end up containing 'Now is >> the >>time fox jumps over the lazy dog the aid of the party'. > > 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 > Not sure, but is not MVCL interruptible?
-- Bob Netzlof a/k/a Sweet Old Bob
