Process Group Management in Cross-Layer Adaptation

Our previous MMCN03 paper reported a cross-layer adaptation framework, GRACE-1, that coordinates the adaptation of CPU frequency/voltage, CPU scheduling, and application quality. GRACE-1 assumes that all application processes (or threads) are independent from each other and adapt individually. This assumption, however, is invalid for multithreaded applications that include dependent and cooperative processes. To support the joint performance requirements of such dependent processes, this paper extends GRACE-1 with a process group management mechanism. The enhanced framework, called GRACE-grp, introduces a new OS abstraction, group control block, to provide the OS-level recognition and support of process groups. Through a group control block, dependent processes can explicitly set up a group and specify their dependency in the OS kernel. Consequently, GRACE-grp schedules and adapts them in a synchronized and consistent manner, thereby delivering joint performance guarantees. We have implemented and evaluated the GRACE-grp framework. Our experimental results show that compared to GRACE-1, GRACE-grp provides better support for the joint quality of dependent processes and reduces CPU energy consumption by 6.2% to 8.7% for each process group.