There was no performance cost to of making NI, OI, and XI atomic. The implementation of the newer machines already happened to work that way, and the engineers were willing to commit to maintaining that behavior on future machines, so the behavior was added to the architecture.
Jim Mulder z/OS Diagnosis, Design, Development, Test IBM Corp. Poughkeepsie NY > What was the performance cost of making NI, OI, and XI block-concurrent? > I suspect many programs will never rely on this behavior, and have never > used tne NIL and OIL macros, yet will bear the burden of any overhead.
