Application-specific quantum for multi-core platform scheduler.

Scheduling has a significant influence on application performance. Deciding on a quantum length can be very tricky, especially when concurrent applications have various characteristics. This is actually the case in virtualized cloud computing environments where virtual machines from different users are colocated on the same physical machine. We claim that in a multi-core virtualized platform, different quantum lengths should be associated with different application types. We apply this principle in a new scheduler called AQL_Sched. We identified 5 main application types and experimentally found the best quantum length for each of them. Dynamically, AQL_Sched associates an application type with each virtual CPU (vCPU) and schedules vCPUs according to their type on physical CPU (pCPU) pools with the best quantum length. Therefore, each vCPU is scheduled on a pCPU with the best quantum length. We implemented a prototype of AQL_Sched in Xen and we evaluated it with various reference benchmarks (SPECweb2009, SPECmail2009, SPEC CPU2006, and PARSEC). The evaluation results show that AQL_Sched outperforms Xen's credit scheduler. For instance, up to 20%, 10% and 15% of performance improvements have been obtained with SPECweb2009, SPEC CPU2006 and PARSEC, respectively.