A task that suspends itself to wait for an I/O completion or to wait for an event from another node in distributed environments is called an I/O blocking task. In conventional hard real-time scheduling theories, there exist several approaches to schedule such I/O blocking tasks within the conventional framework of rate monotonic analysis (RMA). However, most of them are pessimistic. In this paper, we propose effective algorithms that can schedule a task set which includes I/O blocking tasks under dynamic priority assignment. We present a new critical instant theorem for multi-frame task set under dynamic priority assignment. The schedulability is analyzed under the new critical instant theorem. For the schedulability analysis , this paper presents saturation summation which is used to calculate maximum interference function (MIF). With the saturation summation, the schedulability of a task set including I/O blocking tasks can be analyzed more accurately. We propose an algorithm which ...