117,855 research outputs found
Programmable reconfiguration of Physarum machines
Plasmodium of Physarum polycephalum is a large cell capable of solving
graph-theoretic, optimization and computational geometry problems due to its
unique foraging behavior. Also the plasmodium is unique biological substrate
that mimics universal storage modification machines, namely the
Kolmogorov-Uspensky machine. In the plasmodium implementation of the storage
modification machine data are represented by sources of nutrients and memory
structure by protoplasmic tubes connecting the sources. In laboratory
experiments and simulation we demonstrate how the plasmodium-based storage
modification machine can be programmed. We show execution of the following
operations with active zone (where computation occurs): merge two active zones,
multiple active zone, translate active zone from one data site to another,
direct active zone. Results of the paper bear two-fold value: they provide a
basis for programming unconventional devices based on biological substrates and
also shed light on behavioral patterns of the plasmodium
Performance Analysis of a Fibre Channel Switch supporting Node Port Identifier Virtualization
The server virtualization architecture encompassing sharing of storage subsystems among virtual machines using fibre channel fabrics, to improve server utilization and reduce the total cost of ownership, was pioneered by IBM through their System z9 mainframe and its predecessors. With the advent of sharing small computer system interface storage subsystems among host servers through fibre channel based storage area networks, has cropped up new set of security and associated performance issues when the host servers are virtual machines on a single physical server. To address the security issues and reduce the total cost of ownership, IBM introduced new storage virtualization architecture known as node port identifier virtualization enabling thousands of virtual machines on a server to share storage subsystems through a few numbers of host bus adapters.In this paper, we introduce the node port identifier virtualization architecture and the associated fibre channel switch latency performance issue that would affect virtual machine instantiation when supporting thousands of virtual machines. We first show the architectural problem in hard zoning mechanism contributing to the large fibre channel switch latency by actual performance measurements on a switch using hardware simulators. Next, we suggest a modification to the hard zoning mechanism to reduce the fabric channel switch latency significantly and demonstrate the reduction using hardware simulators. The performance issue we have identified and addressed will allow a single fibre channel switch to support thousands of virtual machines on a server using only a few numbers of host bus adapters
Evolving MultiAlgebras unify all usual sequential computation models
It is well-known that Abstract State Machines (ASMs) can simulate
"step-by-step" any type of machines (Turing machines, RAMs, etc.). We aim to
overcome two facts: 1) simulation is not identification, 2) the ASMs simulating
machines of some type do not constitute a natural class among all ASMs. We
modify Gurevich's notion of ASM to that of EMA ("Evolving MultiAlgebra") by
replacing the program (which is a syntactic object) by a semantic object: a
functional which has to be very simply definable over the static part of the
ASM. We prove that very natural classes of EMAs correspond via "literal
identifications" to slight extensions of the usual machine models and also to
grammar models. Though we modify these models, we keep their computation
approach: only some contingencies are modified. Thus, EMAs appear as the
mathematical model unifying all kinds of sequential computation paradigms.Comment: 12 pages, Symposium on Theoretical Aspects of Computer Scienc
Checkpointing as a Service in Heterogeneous Cloud Environments
A non-invasive, cloud-agnostic approach is demonstrated for extending
existing cloud platforms to include checkpoint-restart capability. Most cloud
platforms currently rely on each application to provide its own fault
tolerance. A uniform mechanism within the cloud itself serves two purposes: (a)
direct support for long-running jobs, which would otherwise require a custom
fault-tolerant mechanism for each application; and (b) the administrative
capability to manage an over-subscribed cloud by temporarily swapping out jobs
when higher priority jobs arrive. An advantage of this uniform approach is that
it also supports parallel and distributed computations, over both TCP and
InfiniBand, thus allowing traditional HPC applications to take advantage of an
existing cloud infrastructure. Additionally, an integrated health-monitoring
mechanism detects when long-running jobs either fail or incur exceptionally low
performance, perhaps due to resource starvation, and proactively suspends the
job. The cloud-agnostic feature is demonstrated by applying the implementation
to two very different cloud platforms: Snooze and OpenStack. The use of a
cloud-agnostic architecture also enables, for the first time, migration of
applications from one cloud platform to another.Comment: 20 pages, 11 figures, appears in CCGrid, 201
- âŠ