CRState: checkpoint/restart of OpenCL program for in-kernel applications

Abstract

The checkpoint/restart mechanism is critical in a preemptive system because clusters with this mechanism will be improved in terms of fault tolerance, load balance, and resource utilization. As graphics processing units (GPUs) have more recently become commonplace with the advent of general-purpose computation, and open computing language (OpenCL) programs are portable across various CPUs and GPUs, it is increasingly important to set up checkpoint/restart mechanism in OpenCL programs. However, due to the complexity of the internal computational state of the GPU, there is currently no effective and reasonable checkpoint/restart scheme for OpenCL applications. This paper proposes a feasible system, checkpoint/restart state (CRState), to achieve checkpoint/restart in GPU kernels. The computation states including heap, data segments, local memory, stack and code segments in the underlying hardware are identified and concretized in order to establish an association between the underlying level state and the application level representation. Then, a pre-compiler is developed to insert primitives into OpenCL programs at compile time so that major components of the computation state will be extracted at runtime. Since the computation state is duplicated at application level, such OpenCL programs can be preempted and ported across heterogeneous devices. A comprehensive example and ten authoritative benchmark programs are selected to demonstrate the feasibility and effectiveness of the proposed system.