Patent ID: 6195699
Filing Date: 2001-02-27
Classification: G06F,H04L

Abstract:
A method for the real-time scheduling of access to a resource in a system, said system including at least one channel requiring periodic access to said resource for a predetermined access interval I, said real-time scheduling being performed during successive occurrences of a scheduling period P having a duration equal to an integer multiple of said access interval I, said periodic access occurring at a frequency specified by a channel period, each of said channels having a channel value representing when said periodic access is to next occur, said channel value including a fine value and a coarse value, said coarse value representing an integer multiple of said scheduling period, and said fine value representing an integer multiple of said access interval in the range of 0 to P-I, said method comprising the steps of:(a) counting said access intervals during said scheduling period to provide a value indicating a current access interval;(b) executing a coarse process during said scheduling period, said coarse process including subtracting one from each of said coarse values that is not zero at the beginning of said scheduling period; and(c) executing a fine process repeatedly during said scheduling period, said fine process including the steps of (i) determining a set of current fine values consisting of those of said fine values corresponding to said coarse values that indicate that said periodic access is to occur during said current scheduling period, (ii) determining a smallest current fine value of said set of current fine values, (iii) determining a selected channel from said channels corresponding to said smallest current fine value, (iv) waiting until said smallest current fine value is less than or equal to said current access interval value, (v) triggering said selected channel, and (vi) adjusting said channel value corresponding to said selected channel using said channel period corresponding to said selected channel.