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.

TOFEC: Achieving Optimal Throughput-Delay Trade-off of Cloud Storage Using Erasure Codes

Abstract: Our paper presents solutions using erasure coding, parallel connections to storage cloud and limited chunking (i.e., dividing the object into a few smaller segments) together to significantly improve the delay performance of uploading and downloading data in and out of cloud storage. TOFEC is a strategy that helps front-end proxy adapt to level of workload by treating scalable cloud storage (e.g. Amazon S3) as a shared resource requiring admission control. Under light workloads, TOFEC creates more smaller chunks and uses more parallel connections per file, minimizing service delay. Under heavy workloads, TOFEC automatically reduces the level of chunking (fewer chunks with increased size) and uses fewer parallel connections to reduce overhead, resulting in higher throughput and preventing queueing delay. Our trace-driven simulation results show that TOFEC's adaptation mechanism converges to an appropriate code that provides the optimal delay-throughput trade-off without reducing system capacity. Compared to a non-adaptive strategy optimized for throughput, TOFEC delivers 2.5× lower latency under light workloads; compared to a non-adaptive strategy optimized for latency, TOFEC can scale to support over 3× as many requests. Index Terms—FEC, Cloud storage, Queueing, Delay

On the latency for information dissemination in mobile wireless networks

Abstract: In wireless networks, node mobility may be exploited to assist in information dissemination over time. We analyze the latency for information dissemination in large-scale mobile wireless networks. To study this problem, we map a network of mobile nodes to a network of stationary nodes with dynamic links. We then use results from percolation theory to show that under a constrained i.i.d. mobility model, the scaling behavior of the latency falls into two regimes. When the network is not percolated (subcritical), the latency scales linearly with the initial Euclidean distance between the sender and the receiver; when the network is percolated (supercritical), the latency scales sub-linearly with the distance.

Hermes: Latency optimal task assignment for resource-constrained mobile computing

Abstract: With mobile devices increasingly able to connect to cloud servers from anywhere, resource-constrained devices can potentially perform offloading of computational tasks to either improve resource usage or improve performance. It is of interest to find optimal assignments of tasks to local and remote devices that can take into account the application-specific profile, availability of computational resources, and link connectivity, and find a balance between energy consumption costs of mobile devices and latency for delay-sensitive applications. Given an application described by a task dependency graph, we formulate an optimization problem to minimize the latency while meeting prescribed resource utilization constraints. Different from most of existing works that either rely on an integer linear programming formulation, which is NP-hard and not applicable to general task dependency graph for latency metrics, or on intuitively derived heuristics that offer no theoretical performance guarantees, we propose Hermes, a novel fully polynomial time problem approximation scheme (FPTAS) algorithm to solve this problem. Hermes pros vides a solution with latency no more than (1 + e) times of the minimum while incurring complexity that is an polynomial in problem size and //e We evaluate the performance by using real data set collected from several benchmarks, and show that Hermes improves the latency by 16% (36% for larger scale application) compared to a previously published heuristic and increases CPU computing time by only 0.4% of overall latency.