Design of Kernel-Level Asynchronous Collective Communication

Overlapping computation and communication, not only pointto-point but also collective communications, is an important technique to improve the performance of parallel programs. Since the current nonblocking collective communications have been mostly implemented using an extra thread to progress communication, they have extra overhead due to thread scheduling and context switching. In this paper, a new nonblocking communication facility, called KACC is proposed to provide fast asynchronous collective communications. KACC is implemented in the OS kernel interrupt context to perform non-blocking asynchronous collective operations without an extra thread. The experimental results show that the CPU time cost of this method is sufficiently small. keywords: Non-blocking collective communication, Linux kernel