Latency (engineering)

About: Latency (engineering) is a research topic. Over the lifetime, 3729 publications have been published within this topic receiving 39210 citations. The topic is also known as: lag.

On the design of fast IEEE floating-point adders

Abstract: We present an IEEE floating-point adder (FP-adder) design. The adder accepts normalized numbers, supports all four IEEE rounding modes, and outputs the correctly normalized rounded sum/difference in the format required by the IEEE standard. The latency of the design for double precision is roughly 24 logic levels, not including delays of latches between pipeline stages. Moreover, the design can be easily partitioned into 2 stages consisting of 12 logic levels each, and hence, can be used with clock periods that allow for 12 logic levels between latches. The FP-adder design achieves low latency by combining various optimization techniques such as: a non-standard separation into two paths, a simple rounding algorithm, unifying rounding cases for addition and subtraction, sign-magnitude computation of a difference based on complement subtraction, compound adders, and fast circuits for approximate counting of leading zeros from borrow-save representation. A comparison of our design with other implementations suggests a reduction in the latency by at least two logic levels as well as simplified rounding implementation. A reduced precision version of our algorithm has been verified by exhaustive testing.

Dynamic Control Plane for SDN at Scale

Abstract: As SDN migrates to wide area networks and 5G core networks, a scalable, highly reliable, low latency distributed control plane becomes a key factor that differentiates operator solutions for network control and management. In order to meet the high reliability and low latency requirements under time-varying volume of control traffic, the distributed control plane, consisting of multiple controllers and a combination of out-of-band and in-band control channels, needs to be managed dynamically. To this effect, we propose a novel programmable distributed control plane architecture with a dynamically managed in-band control network, where in-band mode switches communicate with their controllers over a virtual overlay to the data plane with dynamic topology. We dynamically manage the number of controllers, switches, and control flows assigned to each controller as well as traffic over control channels achieving both controller and control traffic load-balancing. We introduce “control flow table” (rules embedded in the flow table of a switch to manage in-band control flows) in order to implement the proposed distributed dynamic control plane. We propose methods for off-loading congested controllers and congested in-band control channels using control flow tables. A validation test-bed and experimental results over multiple topologies are presented to demonstrate the scalability and performance improvements achieved by the proposed dynamic control plane management procedures when the controller CPU and/or availability or throughput of in-band control channels becomes bottlenecks.

Online Parallelized Service Function Chain Orchestration in Data Center Networks

Abstract: In recent years, much attention has been focused on deploying service function chains (SFCs), each of which is composed of a set of virtual network functions (VNFs) in a specified order. This is a promising approach for enabling cloud service providers to deploy user service requests more flexibly while saving costs. However, less effort has been directed toward meeting heterogeneous needs, such as high throughput or low latency of user service requests with heterogeneous bandwidth demands, especially in data center networks (DCNs). In this paper, we propose an efficient orchestration algorithm for online SFC requests. It first splits a large flow into a number of subflows and replicates the same number of sub-SFCs. Each subflow is redirected to one of these “parallelized” sub-SFCs, which is termed a sub-user request. Then, each sub-user request is deployed based on a worst-fit strategy, and VNFs in the same SFC are instantiated on the same server to the greatest possible extent. Our algorithm is expected to enable network load balancing, reducing the delay experienced by small flows while improving the acceptance ratio for user requests. Finally, the simulation results show that the proposed algorithm outperforms other comparable algorithms.

Parallel low latency awareness

Abstract: Methods, systems, and devices for wireless communication are described. A receiving device may detect a signal associated with low latency transmissions and decode a non-low latency communication accordingly. The receiving device may receive an indicator from a transmitting device that indicates where and when low latency communications occur. The indication may specify frequency resources or symbols used by the low latency communication. The indicator may be transmitted during the same subframe as the low latency communication, at the end of a subframe, or during a subsequent subframe. The receiving device may use the indicator to mitigate low latency interference, generate channel estimates, and reliably decode the non-low latency communication. In some cases, the interfering low latency communication may occur within the serving cell of the receiving device; or the interfering low latency communication may occur in a neighboring cell.

A class of highly scalable optical crossbar-connected interconnection networks (SOCNs) for parallel computing systems

Abstract: A class of highly scalable interconnect topologies called the Scalable Optical Crossbar-Connected Interconnection Networks (SOCNs) is proposed. This proposed class of networks combines the use of tunable Vertical Cavity Surface Emitting Lasers (VCSEL's), Wavelength Division Multiplexing (WDM) and a scalable, hierarchical network architecture to implement large-scale optical crossbar based networks. A free-space and optical waveguide-based crossbar interconnect utilizing tunable VCSEL arrays is proposed for interconnecting processor elements within a local cluster. A similar WDM optical crossbar using optical fibers is proposed for implementing intercluster crossbar links. The combination of the two technologies produces large-scale optical fan-out switches that could be used to implement relatively low cost, large scale, high bandwidth, low latency, fully connected crossbar clusters supporting up to hundreds of processors. An extension of the crossbar network architecture is also proposed that implements a hybrid network architecture that is much more scalable. This could be used to connect thousands of processors in a multiprocessor configuration while maintaining a low latency and high bandwidth. Such an architecture could be very suitable for constructing relatively inexpensive, highly scalable, high bandwidth, and fault-tolerant interconnects for large-scale, massively parallel computer systems. This paper presents a thorough analysis of two example topologies, including a comparison of the two topologies to other popular networks. In addition, an overview of a proposed optical implementation and power budget is presented, along with analysis of proposed media access control protocols and corresponding optical implementation.