Latency (engineering)

About: Latency (engineering) is a research topic. Over the lifetime, 7278 publications have been published within this topic receiving 115409 citations. The topic is also known as: lag.

In the blink of an eye: investigating latency perception during stylus interaction

Abstract: While pen computing has become increasingly more popular, device responsiveness, or latency, still plagues such interaction. Although there have been advances in digitizer technology over the last few years, commercial end-to-end latencies are unfortunately similar to those found with touchscreens, i.e., 65 - 120 milliseconds. We report on a prototype stylus-enabled device, the High Performance Stylus System (HPSS), designed to display latencies as low as one millisecond while users ink or perform dragging tasks. To understand the role of latency while inking with a stylus, psychophysical just-noticeable difference experiments were conducted using the HPSS. While participants performed dragging and scribbling tasks, very low levels of latency could be discriminated, i.e., ~1 versus 2 milliseconds while dragging and ~7 versus 40 milliseconds while scribbling. The HPSS and our experimentation have provided further motivation for the implementation of latency saving measures in pen-based hardware and software systems.

Adaptive estimation of latency changes in evoked potentials

Abstract: Changes in latency of evoked potentials (EP) may indicate clinically and diagnostically important changes in the status of the nervous system. A low signal-to-noise ratio of the EP signal makes it difficult to estimate small, transient, time-varying changes in latency, or delays. Here, the authors present an adaptive algorithm that estimates small delay (latency change) values even when EP signal amplitudes are time-varying. When the delay is time invariant, the adaptive algorithm produces an unbiased estimate with delay estimation error less than half of the sampling interval. A lower estimation error variance is obtained when, in a pair of signals, the adaptive algorithm delays the signal with the higher SNR. The adaptive delay estimation algorithm was tested on intra-operative recordings of somatosensory EP, and analysis of those recordings reveals that the anesthetic etomidate produces a step change in the amplitude and latency of the EP signals.

Cache memory exchange optimized memory organization for a computer system

Abstract: Data coherency in a multiprocessor system is improved and data latency minimized through the use of data mapping "fill" requests from any one of the multiprocessor CPUs such that the information requested is acquired through the crossbar switch from the same memory module to which the "victim" data in that CPUs cache must be rewritten. With such an arrangement rewrite latency periods for victim data within the crossbar switch is minimized and the `ships crossing in the night` problem is avoided.

Apparatus and methods for identifying and characterizing latency in a content delivery network

Abstract: Methods and apparatus for identification and characterization of latency in a content delivery network. In one embodiment, interaction of users with content is recorded via the collection of a plurality of tuning records; the latency is then utilize to adjust the timing on the tuning records to account for lapses in time for sending these from between entities of the network and the user devices, and for processing occurring at the devices as required. The latency is determined by taking into account an experimentally or manufacturer-derived device specific latency component, and a network latency component. The network latency component is determined in one variant by sending a message to the device from the network requesting a current system time (or other response). Once the timing of the tuning records is adjusted, these tuning records may be relied upon as being accurate representations of subscriber interaction with content on a second-by-second basis. Accordingly, tuning records may be obtained and analyzed for content which lasts for very short periods of time (e.g. advertisements).

Joint latency and cost optimization for erasurecoded data center storage

Abstract: Modern distributed storage systems offer large capacity to satisfy the exponentially increasing need of storage space. They often use erasure codes to protect against disk and node failures to increase reliability, while trying to meet the latency requirements of the applications and clients. This paper provides an insightful upper bound on the average service delay of such erasure-coded storage with arbitrary service time distribution and consisting of multiple heterogeneous files. Not only does the result supersede known delay bounds that only work for homogeneous files, it also enables a novel problem of joint latency and storage cost minimization over three dimensions: selecting the erasure code, placement of encoded chunks, and optimizing scheduling policy. The problem is efficiently solved via the computation of a sequence of convex approximations with provable convergence. We further prototype our solution in an open-source, cloud storage deployment over three geographically distributed data centers. Experimental results validate our theoretical delay analysis and show significant latency reduction, providing valuable insights into the proposed latency-cost tradeoff in erasure-coded storage.