109107038
Lambda Station: Alternate network path forwarding for production SciDAC applications
The LHC era will start very soon, creating immense data volumes capable of demanding allocation of an entire network circuit for task-driven applications. Circuit-based alternate network paths are one solution to meeting the LHC high bandwidth network requirements. The Lambda Station project is aimed at addressing growing requirements for dynamic allocation of alternate network paths. Lambda Station facilitates the rerouting of designated traffic through site LAN infrastructure onto so-called 'high-impact' wide-area networks. The prototype Lambda Station developed with Service Oriented Architecture (SOA) approach in mind will be presented. Lambda Station has been successfully integrated into the production version of the Storage Resource Manager (SRM), and deployed at US CMS Tier1 center at Fermilab, as well as at US-CMS Tier-2 site at Caltech. This paper will discuss experiences using the prototype system with production SciDAC applications for data movement between Fermilab and Caltech. The architecture and design principles of the production version Lambda Station software, currently being implemented as Java based web services, will also be presented in this paper.
15821307
The performance analysis of linux networking - Packet receiving
The computing models for high-energy physics experiments are becoming ever more globally distributed and grid-based, both for technical reasons (e.g., to place computational and data resources near each other and the demand) and for strategic reasons (e.g., to leverage equipment investments). To support such computing models, the network and end systems, computing and storage, face unprecedented challenges. One of the biggest challenges is to transfer scientific data sets - now in the multi-petabyte (10^1^5 bytes) range and expected to grow to exabytes within a decade - reliably and efficiently among facilities and computation centers scattered around the world. Both the network and end systems should be able to provide the capabilities to support high bandwidth, sustained, end-to-end data transmission. Recent trends in technology are showing that although the raw transmission speeds used in networks are increasing rapidly, the rate of advancement of microprocessor technology has slowed down. Therefore, network protocol-processing overheads have risen sharply in comparison with the time spent in packet transmission, resulting in degraded throughput for networked applications. More and more, it is the network end system, instead of the network, that is responsible for degraded performance of network applications. In this paper, the Linux system's packet receive process is studied from NIC to application. We develop a mathematical model to characterize the Linux packet receiving process. Key factors that affect Linux systems' network performance are analyzed.
10630563
Lambda Station: On-Demand Flow Based Routing for Data Intensive Grid Applications Over Multitopology Networks
Lambda Station is an ongoing project of Fermi National Accelerator Laboratory and the California Institute of Technology. The goal of this project is to design, develop and deploy network services for path selection, admission control and flow based forwarding of traffic among data- intensive Grid applications such as are used in High Energy Physics and other communities. Lambda Station deals with the last-mile problem in local area networks, connecting production clusters through a rich array of wide area networks. Selective forwarding of traffic is controlled dynamically at the demand of applications. This paper introduces the motivation of this project, design principles and current status. Integration of Lambda Station client API with the essential Grid middleware such as the dCache/SRM Storage Resource Manager is also described. Finally, the results of applying Lambda Station services to development and production clusters at Fermilab and Caltech over, advanced networks such as DOE's UltraScience Net and NSF's UltraLight is covered.
203169
An evaluation of parallel optimization for OpenSolaris® network stack
Computing is now shifting towards multiprocessing. The fundamental goal of multiprocessing is improved performance through the introduction of additional hardware threads or cores (referred to as “cores” for simplicity). Modern network stacks can exploit parallel cores to allow either message-based parallelism or connection-based parallelism as a means to enhance performance. OpenSolaris has redesigned and parallelized to better utilize additional cores. Three special technologies, named Softring Set, Soft ring and Squeue are introduced in OpenSolaris for stack parallelization. In this paper, we study the OpenSolaris packet receiving process and its core parallelism optimization techniques. Experiment results show that these techniques allow OpenSolaris to achieve better network I/O performance in multiprocessing environments; however, network stack parallelization has also brought extra overheads for system. An effective and efficient network I/O optimization in multiprocessing environments is required to cross all levers of the network stack from network interface to application.
6103735
Sorting Reordered Packets with Interrupt Coalescing
TCP performs poorly in networks with serious packet reordering. Processing reordered packets in the TCP-layer is costly and inefficient, involving interaction of the sender and receiver. Motivated by the interrupt coalescing mechanism that delivers packets upward for protocol processing in blocks, we propose a new strategy, Sorting Reordered Packets with Interrupt Coalescing (SRPIC), to reduce packet reordering in the receiver. SRPIC works in the network device driver; it makes use of the interrupt coalescing mechanism to sort the reordered packets belonging to the same TCP stream in a block of packets before delivering them upward; each sorted block is internally ordered. Experiments have proven the effectiveness of SRPIC against forward path reordering.
55533633
Building global HEP systems on Kerberos
As an underpinning of AFS and Windows 2000, and as a formally proven security protocol [1] in its own right, Kerberos is ubiquitous among HEP sites. Fermilab and users from other sites have taken advantage of this and built a diversity of distributed applications over Kerberos v5. We present several projects in which this security infrastructure has been leveraged to meet the requirements of geographically dispersed collaborations. These range from straightforward ''Kerberization'' of applications such as database and batch services, to quick tricks like simulating a user-authenticated web service with AFS and the ''file'': schema, to more complex systems. Examples of the latter include experiment control room operations and the Central Analysis Farm (CAF). We present several use cases and their security models, and examine how they attempt to address some of the outstanding problems of secure distributed computing: delegation of the least necessary privilege; establishment of trust between a user and a remote processing facility; credentials for long-queued or long-running processes, and automated processes running without any user's presence; security of remotely-stored credentials; and ability to scale to the numbers of sites, machines and users expected in the collaborations of the coming decade.
120207464
Electron-Nuclear Potential Fields from Hyperfine Structure