Lightweight Kernel Operating System

A lightweight kernel (LWK) operating system is one used in a large computer with many processor cores, termed a parallel computer.

A massively parallel high-performance computing (HPC) system is particularly sensitive to operating system overhead. Traditional multi-purpose operating systems are designed to support a wide range of usage models and requirements. To support the range of needs, a large number of system processes are provided and are often inter-dependent on each other. The computing overhead of these processes leads to an unpredictable amount of processor time available to a parallel application. A very common parallel programming model is referred to as the bulk synchronous parallel model which often employs Message Passing Interface (MPI) for communication. The synchronization events are made at specific points in the application code. If one processor takes longer to reach that point than all the other processors, everyone must wait. The overall finish time is increased. Unpredictable operating system overhead is one significant reason a processor might take longer to reach the synchronization point than the others.

Custom lightweight kernel operating systems, currently used on some of the fastest computers in the world, help alleviate this problem. The IBM Blue Gene line of supercomputers runs various versions of CNK operating system. The Cray XT4 and Cray XT5 supercomputers run Compute Node Linux.Sandia National Laboratories has an almost two-decade commitment to lightweight kernels on its high-end HPC systems. Sandia and University of New Mexico researchers began work on SUNMOS for the Intel Paragon in the early 1990s. This operating system evolved into the Puma, Cougar, and Catamount operating systems deployed on ASCI Red and Red Storm. Sandia continues its work in LWKs with a new R&D effort, called kitten.

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