arXiv subjects

José L. Sánchez

Publications and source records attributed to José L. Sánchez.

6 recordsLinked to original sources

arXiv2026

On the Power Saving in High-Speed Ethernet-based Networks for Supercomputers and Data Centers

The increase in computation and storage has led to a significant growth in the scale of systems powering applications and services, raising concerns about sustainability and operational costs. In this paper, we explore power-saving techniques in high-performance computing (HPC) and datacenter networks, and their relation with performance degradation. From this premise, we propose leveraging Energy Efficient Ethernet (EEE) protocol, with the flexibility to extend to conventional Ethernet or upcoming Ethernet-derived interconnect versions of BXI and Omnipath. We analyze the PerfBound power-saving mechanism, identifying possible improvements and modeling it into a simulation framework. Through different experiments, we examine its impact on performance and determine the most appropriate interconnect. We also study traffic patterns generated by selected HPC and machine learning applications to evaluate the behavior of power-saving techniques. From these experiments, we provide an analysis of how applications affect system and network energy consumption. Based on this, we disclose the weakness of dynamic power-down mechanisms and propose an approach that improves energy reduction with minimal or no performance penalty. To the best of our knowledge, this work presents the first thorough analysis of PerfBound and an enhancement to the technique, while also targeting emerging post-exascale networks.

cs.NI↗

arXiv2026

Characterization of Real Communication Patterns and Congestion Dynamics in HPC Interconnection Networks

The interconnection network is a key component of Supercomputers and Data centers, and its design must cope with the increasing communication demands of current applications and services; otherwise, it may become a system bottleneck. The most challenging network design issues are the topology, routing algorithm, flow control, and power efficiency. However, even the most efficient interconnection networks may suffer severe performance degradation due to congestion, especially under specific network traffic patterns generated by communication operations in high-performance computing~(HPC), deep learning training, or online data-intensive services. In this context, characterizing and modeling these communication operations and the network traffic patterns they generate is a fundamental challenge for studying their impact on network performance. This paper presents a methodology, based primarily on the VEF Traces framework, to characterize, model, and simulate the communication patterns of representative computing- and data-intensive applications. More precisely, we have extended the VEF traces framework with tools that enable us to characterize network congestion, either directly from VEF traces or via simulations. We have analyzed a set of VEF traces obtained from runs of NEST, GROMACS, LAMMPS, and PATMOS on several Supercomputers. In these studies, we identify potential congestion scenarios that arise in realistic network configurations when certain collective operations are performed.

cs.NI↗

arXiv2025

Combined power management and congestion control in High-Speed Ethernet-based Networks for Supercomputers and Data Centers

The demand for computer in our daily lives has led to the proliferation of Datacenters that power indispensable many services. On the other hand, computing has become essential for some research for various scientific fields, that require Supercomputers with vast computing capabilities to produce results in reasonable time. The scale and complexity of these systems, compared to our day-to-day devices, are like comparing a cell to a living organism. To make them work properly, we need state-of-the-art technology and engineering, not just raw resources. Interconnecting the different computer nodes that make up a whole is a delicate task, as it can become the bottleneck for the whole infrastructure. In this work, we explore two aspects of the network: how to prevent degradation under heavy use with congestion control, and how to save energy when idle with power management; and how the two may interact.

cs.AR↗

arXiv2021

UPR: Deadlock-Free Dynamic Network Reconfiguration by Exploiting Channel Dependency Graph Compatibility

Deadlock-free dynamic network reconfiguration process is usually studied from the routing algorithm restrictions and resource reservation perspective. The dynamic nature yielded by the transition process from one routing function to another is often managed by restricting resource usage in a static predefined manner, which often limits the supported routing algorithms and/or inactive link patterns, or either requires additional resources such as virtual channels. Exploiting compatibility between routing functions by exploring their associated Channel Dependency Graphs (CDG) can take a great benefit from the dynamic nature of the reconfiguration process. In this paper, we propose a new dynamic reconfiguration process called Upstream Progressive Reconfiguration (UPR). Our algorithm progressively performs dependency addition/removal in a per channel basis relying on the information provided by the CDG while the reconfiguration process takes place. This gives us the opportunity to foresee compatible scenarios where both routing functions coexist, reducing the amount of resource drainage as well as packet injection halting.

cs.NI↗

arXiv2020

TDSR: Transparent Distributed Segment-Based Routing

Component reliability and performance pose a great challenge for interconnection networks. Future technology scaling such as transistor integration capacity in VLSI design will result in higher device degradation and manufacture variability. As a consequence, changes in the network arise, often rendering irregular topologies. This paper proposes a topology-agnostic distributed segment-based algorithm able to handle switch discovery in any topology while guaranteeing connectivity among switches. The proposal, known as Transparent Distributed Segment-Based Routing (TDSR), has been applied to meshes with defective link configurations.

cs.DC↗

arXiv2018

Light pollution in shallow coastal waters: aquaculture farming in the Galician Atlantic shoreline

Artificial light at night is a relevant environmental stressor whose unwanted consequences have been documented by a growing body of research. In this work we analize the loss of the natural darkness of the night in aquaculture farms located in shallow waters close to the shoreline, in the Atlantic coast of Galicia. High-luminance LED lampposts are switched-on the whole night long for surveillance purposes, significantly increasing the light levels throughout the whole water column, from the surface to the seabed. Measured in terms of the weighted radiance associated with the significant magnitude m1/3, the zenithal brightness at these locations is 125 times higher than should correspond to a pristine natural site. Given the potential severity of the environmental effects of artificial light at night, the dubious efficacy of light per se as a theft deterrence factor, and the availability of more efficient and environmentally friendly technologies for surveillance, the use of permanent floodlight sources in coastal areas is strongly discouraged and should be restricted as much as possible.

physics.ao-ph↗