| 摘要 |
In accordance with one embodiment of the invention, a broadcast server system computes a feasible stretch value for use in scheduling job requests. A stretch value provides an indication of the delay experienced by each job request to complete, when the broadcast server processes many jobs concurrently. A processing time is calculated for each job request based on, the size of the job request and the bandwidth of the server downlink. Thereafter, a stretch value is proposed. The server system computes a deadline for each job to be the arrival time of the job request plus the product of the processing time and the proposed stretch value. Thereafter, each job request is scheduled, based on an "earliest deadline first" arrangement, wherein the job request that has the earliest deadline is scheduled first, the job request having the next earliest deadline is scheduled second, etc. The proposed stretch value is deemed feasible if each pending job request can be completed prior to its deadline. If the proposed stretch value is deemed not feasible, it is adjusted iteratively until a feasible stretch value is found. The feasible stretch value is then utilized to schedule the job requests to be broadcast by the system. When the broadcast of a job request is completed, all job requests for the same data item, which arrived prior to the start of the broadcast, are eliminated from the pending job requests.
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