Scheduling Tasks with Exponential Service Times on Non-Identical Processors to Minimize Various Cost Functions
نویسندگان
چکیده
We consider preemptive scheduling of N tasks on m processors; processors have different speeds, tasks require amounts of work which are exponentially distributed, with different parameters. The policies of assigning at every moment the task with shortest (longest) expected processing time among those not yet completed to the fastest processor available, second shortest (longest) to the second fastest etc., are examined, and shown to minimize expected values of various cost functions. As special cases we obtain policies which minimize expected flowtime, expected makespan and expected lifetime of a series system with m component locations and N spares. EXPONENTIAL DISTRIBUTION; DYNAMIC PROGRAMMING; MULTIPROCESSORS; STOCHASTIC PREEMPTIVE SCHEDULING; RELIABILITY OF SERIES SYSTEM WITH SPARES
منابع مشابه
The Power of Choice in Scheduling Parallel Tasks
A malleable parallel task is one that can be executed on any number of processors, with its execution time being a function of the number of processors allotted to it. A nonmalleable parallel task is one that requires a speciic number of processors. Given n independent parallel tasks and m identical processors, we consider the problem of scheduling these tasks to minimize average completion tim...
متن کاملScheduling multiprocessor tasks on two parallel processors
In this work scheduling multiprocessor tasks on two parallel identical processors is considered. Multiprocessor tasks can be executed by more than one processor at the same moment of time. We analyze scheduling unit execution time and preemptable tasks to minimize schedule length and maximum lateness. Cases with ready times, due-dates and precedence constraints are discussed.
متن کاملMakespan Minimization of task graphs with random task running times
The problem of scheduling a set of tasks on two parallel and identical processors is considered. The executions of tasks are constrained by precedence relations. The running times of the tasks are independent random variables with a common exponential distribution. The goal of scheduling is to minimize the makespan, i.e. the maximum task completion time. A simple optimal preemptive policy is pr...
متن کاملOptimal Two Stages Specially Structured Flow Shop Scheduling: Minimize the Rental Cost with Independent Setup Time
One of the earliest results in flow shop scheduling theory is an algorithm given by Johnson’s [1] for scheduling jobs on two or three machines to minimize the total elapsed time whenever the processing times of jobs are random. The present paper is an attempt to develop a heuristic algorithm for two stages specially structured flow shop scheduling in which the processing times of the jobs a...
متن کاملبهینه سازی زمان بندی الگوریتم های موازی با استفاده از الگوریتم ژنتیک
In scheduling, a set of machines in parallel is a setting that is important, from both the theoretical and practical points of view. From the theoretical viewpoint, it is a generalization of the single machine scheduling problem. From the practical point of view the occurrence of resources in parallel is common in real-world. When machines are computers, a parallel program can be conceived as a...
متن کامل