Applications of SRPT Scheduling with Inaccurate Information

The Shortest Remaining Processing Time (SRPT) scheduling policy was proven, in the 1960s, to yield the smallest mean response time, and recently it was proven its performance gain over Processor Sharing (PS) usually does not come at the expense of large jobs. However, despite the many advantages of SRPT scheduling, it is not widely applied. One important reason for the sporadic application of SRPT scheduling is that accurate job size information is often unavailable. Our previous work addressed the performance and fairness issues of SRPT scheduling when job size information is inaccurate. We found that SRPT (and FSP) scheduling outperforms PS as long as there exists a (rather small) amount of correlation between the estimated job size and the actual job size. In the work we summarize here, we have developed job size estimation techniques to support the application of SRPT to web server and Peer-to-Peer server side scheduling. We have evaluated our techniques with extensive simulation studies and real world implementation