A method, system and computer program product for avoiding unnecessary
grace period token processing while detecting a grace period without
atomic instructions in a read-copy update subsystem or other processing
environment that requires deferring removal of a shared data element
until pre-existing references to the data element are removed. Detection
of the grace period includes establishing a token to be circulated
between processing entities sharing access to the data element. A grace
period elapses whenever the token makes a round trip through the
processing entities. A distributed indicator associated with each
processing entity indicates whether there is a need to perform removal
processing on any shared data element. The distributed indicator is
processed at each processing entity before the latter engages in token
processing. Token processing is performed only when warranted by the
distributed indicator. In this way, unnecessary token processing can be
avoided when the distributed indicator does not warrant such processing.