Efficient exploitation of kernel access to Infiniband: a software DSM example

The Infiniband (IB) system area network (SAN) enables applications to access hardware directly from the user level, reducing the overhead of user-kernel crossings during data transfer. However, distributed applications that exhibit close coupling between network and OS services may benefit from accessing IB from the kernel through IB's native verbs interface, which permits tight integration of these services. We assess this approach using a sequential-consistency distributed shared memory (DSM) system as an example. We first develop primitives that abstract the low-level communication and kernel details, and efficiently serve the application's communication, memory,and scheduling needs. Next, we combine the primitives to form a kernel DSM protocol. The approach is evaluated using our full-fledged Linux kernel DSM implementation over Infiniband.