PUMA: An Operating System for Massively Parallel Systems

This paper presents an overview of PUMA, (Performanceoriented, User-managed Messaging Architecture), a message passing kernel. Message passing in PUMA is based on portals—an opening in the address space of an application process. Once an application process has established a portal, other processes can write values into the portal using a simple send operation. Because messages are written directly into the address space of the receiving process, there is no need to buffer messages in the PUMA kernel and later copy them into the applications address space. PUMA consists of two components: the quintessential kernel (Q-Kernel) and the process control thread (PCT). While the PCT provides management decisions, the QKernel controls access and implements the policies specified by the PCT.