In accordance with one embodiment of the invention, a central server
system computes a feasible stretch value for use in scheduling the
servicing of job requests by a plurality of communication channels. A
stretch value provides an indication of the delay experienced by each job
request to complete, when the central 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 channel.
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. According to the EDF methodology, the central server
schedules for service, via k local channel servers, the job requests,
such that the k job requests which have the earliest deadlines are
serviced first by the k local channel servers and the remaining job
requests are subsequently serviced as the local channel servers become
available. 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 serviced by the channels.