Lightweight kernel operating system: Difference between revisions

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{{Orphan|date=April 2011}}

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 [[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''' (LWK) 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—Compute Node Kernel .<ref name=bgl-cnk>{{cite paperjournal

| title = Designing a Highly-Scalable Operating System: The Blue Gene/L Story

| publisher = Proceedings of the 2006 ACM/IEEE International Conference for High-Performance Computing, Networking, Storage, and Analysis (SC’06)

| author = Moreira, Jose, et al

| date = 2006-11

}}</ref> .

The [[Cray XT4]] and [[Cray XT5]] supercomputers run [[Compute Node Linux]] .<ref name=cnl-dwb>{{cite paperjournal

| title = Compute Node Linux: Overview, progress to date, and roadmap

| publisher = Proceedings of the 2007 Cray User Group Annual Technical Conference

| author = Wallace, D.

| date = 2007-05

}}</ref> . [[Sandia National Laboratories]] has an almost two-decade commitment to Lightweight Kernels on its high-end HPC systems .<ref name=lwk-rr>{{cite paperjournal

| title = Designing and Implementing Lightweight Kernels for Capability Computing

| publisher = Concurrency and Computation: Practice and Experience

| author = Riesen, Rolf, et al

| date = 2009-04

}}</ref> .

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 .<ref name=pedretti>{{cite web

| url = https://software.sandia.gov/trac/kitten

| title = Kitten Lightweight Kernel

}}</ref> .

The design goals of these operating systems are:

* Targeted at massively parallel environments composed of thousands of processors with distributed memory and a tightly coupled network.

* Provide necessary support for scalable, performance-oriented scientific applications.

* Offer a suitable development environment for parallel applications and libraries.

* Emphasize efficiency over functionality.

* Maximize the amount of resources (e.g. CPU, memory, and network bandwidth) allocated to the application.

* Seek to minimize time to completion for the application. <ref name=cat-smk>{{cite paperjournal

| title = Software Architecture of the Light Weight Kernel, Catamount

| publisher = Proceedings of the 2005 Cray User Group Annual Technical Conference