6238247
A Transport-Friendly NIC for Multicore/Multiprocessor Systems
Receive side scaling (RSS) is an NIC technology that provides the benefits of parallel receive processing in multiprocessing environments. However, RSS lacks a critical data steering mechanism that would automatically steer incoming network data to the same core on which its application thread resides. This absence causes inefficient cache usage if an application thread is not running on the core on which RSS has scheduled the received traffic to be processed and results in degraded performance. To remedy the RSS limitation, Intel's Ethernet Flow Director technology has been introduced. However, our analysis shows that Flow Director can cause significant packet reordering. Packet reordering causes various negative impacts in high-speed networks. We propose an NIC data steering mechanism to remedy the RSS and Flow Director limitations. This data steering mechanism is mainly targeted at TCP. We term an NIC with such a data steering mechanism “A Transport-Friendly NIC” (A-TFN). Experimental results have proven the effectiveness of A-TFN in accelerating TCP/IP performance.
60653560
A collaborative network middleware project by Lambda Station, TeraPaths, and Phoebus
The TeraPaths, Lambda Station, and Phoebus projects, funded by the US Department of Energy, have successfully developed network middleware services that establish on-demand and manage true end-to-end, Quality-of-Service (QoS) aware, virtual network paths across multiple administrative network domains, select network paths and gracefully reroute traffic over these dynamic paths, and streamline traffic between packet and circuit networks using transparent gateways. These services improve network QoS and performance for applications, playing a critical role in the effective use of emerging dynamic circuit network services. They provide interfaces to applications, such as dCache SRM, translate network service requests into network device configurations, and coordinate with each other to setup up end-to-end network paths. The End Site Control Plane Subsystem (ESCPS) builds upon the success of the three projects by combining their individual capabilities into the next generation of network middleware. ESCPS addresses challenges such as cross-domain control plane signalling and interoperability, authentication and authorization in a Grid environment, topology discovery, and dynamic status tracking. The new network middleware will take full advantage of the perfSONAR monitoring infrastructure and the Inter-Domain Control plane efforts and will be deployed and fully vetted in the Large Hadron Collider data movement environment.
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.
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.
11433371
Potential performance bottleneck in Linux TCP
TCP is the most widely used transport protocol on the Internet today. Over the years, especially recently, due to requirements of high bandwidth transmission, various approaches have been proposed to improve TCP performance. The Linux 2.6 kernel is now preemptible. It can be interrupted mid-task, making the system more responsive and interactive. However, we have noticed that Linux kernel preemption can interact badly with the performance of the networking subsystem. In this paper we investigate the performance bottleneck in Linux TCP. We systematically describe the trip of a TCP packet from its ingress into a Linux network end system to its final delivery to the application; we study the performance bottleneck in Linux TCP through mathematical modeling and practical experiments; finally we propose and test one possible solution to resolve this performance bottleneck in Linux TCP.
1290244
Statistical mechanics in a covariant gauge.
Many astrophysical and other problems require renormalizable field-theory calculations to be performed at nonzero temperature. An operator formalism is presented here for gauge fields coupled to scalars in the covariant X Hooft-Feynman gauge. It is shown that the introduction of projection operators into thermal averages can be avoided by a simple change in the definition of the trace operation. The partition function and finite-temperature propagators are derived in real time for spontaneously broken gauge theories.
120207464
Electron-Nuclear Potential Fields from Hyperfine Structure