Time Management in the Quest-V RTOS ∗

Quest-V is a new system currently under development for multicore processors. It comprises a collection of separate kernels operating together as a distributed system on a chip. Each kernel is isolated from others using virtualization techniques, so that faults do not propagate through out the entire system. This multikernel design supports online fault recovery of compromised or misbehaving services without the need for full system reboots. While the system is designed for high-confidence computing environments that require dependability, Quest-V is also designed to be predictable. It treats time as a first-class resource, requiring that all operations are properly accounted and handled in real-time. This paper focuses on the design aspects of Quest-V that relate to how time is managed. Special attention is given to how Quest-V manages time in four key areas: (1) scheduling and migration of threads and virtual CPUs, (2) I/O management, (3) communication, and (4) fault re-