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> The following is from the Priority and Fairness section. > > > When two threads A and B are blocked on a given mutex or condition > > variable, and A blocked before B, then > > 1. if A's priority is not less than B's priority, A will wakeup before > > B > > 2. otherwise, A will wakeup before or after B. > > For RT support, the highest priority task should wake up first. If the > priorities are the same, then it really doesn't matter so I would > suggest that the thread blocked first wakes first. > > Thus to not preclude the future RT-SRFI, the section should read: > > 1. The highest priority thread will wake first. > 2. If multiple threads have the same priority, the first to block > will be the first to wake. > > Although this does not produce the same schedule of tasks as the above > definition, I can't envision an application where this behavior is not > preferable. Perhaps Marc or someone else can give an example of an > application where blocking order should take precedence over priority > when it comes to waking a task. The current specification in the Priority and Fairness section is sufficiently weak to allow a FIFO implementation, i.e. an implementation can ignore priorities but not arrival time. FIFO is simple to implement and efficient and provides a certain fairness guarantee, but it is not particularly useful in a real-time context. A priority queue based implementation which would be useful in a real-time context is not excluded by the specification. Your specification requires a priority queue based implementation. It's the specification I would expect in a RT-SRFI. Marc