Generalized rate monotonic schedulability bounds using relative period ratios

Comments on “Generalized rate monotonic schedulability bounds using relative period ratios”

“…In the proof of Theorem 3 in [7], the authors implicitly assume that if a task set is not schedulable, then the task with the longest period, which has the lowest priority, would miss its deadline. It is not always correct, especially when the maximum period ratio is very large.…”

“…(5) can be applied by applying the concept of virtual period for task sets with period ratio greater than or equal to 2 (that is, T n 2T 1 ). However, the claim made in [7] is not exactly correct. In this Letter, a counter-example is presented showing the above claim is not applicable to all task sets.…”

“…Recently, this result is further generalized in [7]. They introduced the concept of conditional bound CB(Z x ), where Z x is a tuple of x period ratios.…”

“…, r n−1 ) for 1 x n − 1. In [7], it is shown that 0020-0190/$ -see front matter © 2010 Elsevier B.V. All rights reserved. …”

“…It was claimed in [7] that the schedulability conditions given in Eq. (5) can be applied by applying the concept of virtual period for task sets with period ratio greater than or equal to 2 (that is, T n 2T 1 ).…”