The past few decades have seen software and hardware growing more heterogeneous and layered in abstractions. This trend produced many benefits for hiding complexity and increasing efficiency and modularity. But it also makes reasoning about performance and identifying its underlying factors more challenging because of the presence of performance variability. Moreover, performance variability can prevent synchronous applications from scaling and server applications from meeting service-level agreements.

Reducing the energy consumption of data centers is critical to meeting international climate goals and lowering operation costs. Container orchestration platforms can help counteract this trend by optimally placing applications across the infrastructure to increase resource utilization and reduce energy consumption. But platforms in use today are still energy-agnostic and do not offer any insights into energy consumption. In this paper, we present a monitoring framework and a new modeling approach for resource usage in data centers. The model captures heterogeneous hardware and software and acts as input for a Graph Neural Network (GNN) to predict power consumption. Based on this model, we derive a set of container scheduling algorithms that opportunistically schedule applications based on the estimated energy impact of incoming containers. Our results show that the GNN-based prediction model is very accurate and achieves an average RMSE (Root Mean Square Error) of 7.5%. We have implemented a custom scheduler to demonstrate the benefits of using our prediction, and our scheduler can decrease energy consumption on average by 6.2% without any code changes for the application and without increasing workload completion time compared to the default Kubernetes scheduler.

Summary Since the dawn of quantum computing (QC), theoretical developments like Shor's algorithm proved the conceptual superiority of QC over traditional computing. However, such quantum supremacy claims are difficult to achieve in practice because of the technical challenges of realizing noiseless qubits. In the near future, QC applications will need to rely on noisy quantum devices that offload part of their work to classical devices. One way to achieve this is by using parameterized quantum circuits in optimization or even in machine learning tasks. The energy requirements of quantum algorithms have not yet been studied extensively. In this article, we explore several optimization algorithms using both theoretical insights and numerical experiments to understand their impact on energy consumption. Specifically, we highlight why and how algorithms like quantum natural gradient descent, simultaneous perturbation stochastic approximations or circuit learning methods, are at least to more energy efficient than their classical counterparts; why feedback‐based quantum optimization is energy‐inefficient; and how techniques like Rosalin can improve the energy efficiency of other algorithms by a factor of 20. Finally, we use the NchooseK high‐level programming model to run optimization problems on both gate‐based quantum computers and quantum annealers. Empirical data indicate that these optimization problems run faster, have better success rates, and consume less energy on quantum annealers than on their gate‐based counterparts.

The growing convergence of high-performance, data analytics, and machine-learning applications is increasingly pushing computing systems toward heterogeneous processors and specialized hardware accelerators. Hardware heterogeneity, in turn, leads to finer-grained workflows. State-of-the-art server-less computing resource managers do not currently provide efficient scheduling of such fine-grained tasks on systems with heterogeneous CPUs and specialized hardware accelerators (e.g., GPUs and FPGAs). Working with fine-grained tasks presents an opportunity for more efficient energy use via new scheduling models. Our proposed scheduler enables technologies like Nvidia's Multi-Process Service (MPS) to pack multiple fine-grained tasks on GPUs efficiently. Its advantages include better co-location of jobs and better sharing of hardware resources such as GPUs that were not previously possible on container orchestration systems. We propose a Kubernetes-native energy-aware scheduler that integrates with our heterogeneous framework. Combining fine-grained resource scheduling on heterogeneous hardware and energy-aware scheduling results in up to 17.6% improvement in makespan, up to 20.16% reduction in energy consumption for CPU workloads, and up to 58.15% improvement in makespan, and up to 28.92% reduction in energy consumption for GPU workloads.

With the slowing of Moore's law and decline of Dennard scaling, computing systems increasingly rely on specialized hardware accelerators in addition to general-purpose compute units. Increased hardware heterogeneity necessitates disaggregating applications into workflows of fine-grained tasks that run on a diverse set of CPUs and accelerators. Current accelerator delivery models cannot support such applications efficiently, as (1) the overhead of managing accelerators erases performance benefits for fine-grained tasks; (2) exclusive accelerator use per task leads to underutilization; and (3) specialization increases complexity for developers.

Women are acutely underrepresented in the HPC workforce. Addressing this gap requires accurate metrics on the representation of women and its associated factors. The goal of this paper is to provide current, broad, and reproducible data on this gender gap. Specifically, this study provides in-depth statistics on women's representation in HPC conferences, especially for authors of peer-reviewed papers, who serve as the keystone for future advances in the field.

The successful development and deployment of large-scale Internet services depends critically on performance. Even small regressions in processing time can translate directly into significant energy and user experience costs. Despite the widespread use of distributed server infrastructure (e.g., in cloud computing and Web services), there is little research on how to benchmark such systems to obtain valid and precise inferences with minimal data collection costs. Correctly A/B testing distributed Internet services can be surprisingly difficult because interdependencies between user requests (e.g., for search results, social media streams, photos) and host servers violate assumptions required by standard statistical tests. We develop statistical models of distributed Internet service performance based on data from Perflab, a production system used at Facebook which vets thousands of changes to the company's codebase each day. We show how these models can be used to understand the tradeoffs between different benchmarking routines, and what factors must be taken into account when performing statistical tests. Using simulations and empirical data from Perflab, we validate our theoretical results, and provide easy-to-implement guidelines for designing and analyzing such benchmarks.

Key-value stores are a vital component in many scale-out enterprises, including social networks, online retail, and risk analysis. Accordingly, they are receiving increased attention from the research community in an effort to improve their performance, scalability, reliability, cost, and power consumption. To be effective, such efforts require a detailed understanding of realistic key-value workloads. And yet little is known about these workloads outside of the companies that operate them. This paper aims to address this gap.

Large-scale data centers consume megawatts in power and cost hundreds of millions of dollars to equip. Reducing the energy and cost footprint of servers can therefore have substantial impact. Web, Grid, and cloud servers in particular can be hard to optimize, since they are expected to operate under a wide range of workloads. For our upcoming data center, we set out to significantly improve its power efficiency, cost, reliability, serviceability, and environmental footprint. To this end, we redesigned many dimensions of the data center and servers in conjunction. This paper focuses on our new server design, combining aspects of power, motherboard, thermal, and mechanical design. We calculate and confirm experimentally that our custom-designed servers can reduce power consumption across the entire load spectrum while at the same time lower acquisition and maintenance costs. Importantly, our design does not reduce the servers' performance or portability, which would otherwise limit its applicability.

Scalable management of distributed resources is one of the major challenges when building large-scale clusters for high-performance computing. This task includes transparent fault tolerance, efficient deployment of resources and support for all the needs of parallel applications: parallel I/O, deterministic behavior and responsiveness. These challenges may seem daunting with commodity hardware and operating systems, since they were not designed to support a global, single management view of a large-scale system. In this paper we propose and demonstrate an abstract network interface in the cluster interconnect to facilitate the implementation of a simple yet powerful global operating system. This system, which can be thought of as a coarse-grain SIMD operating system, can allow commodity clusters to grow to thousands of nodes, while still retaining the usability and performance of the single-node workstation.

Although clusters are a popular form of high-performance computing, they remain more difficult to manage than sequential systems - or even symmetric multiprocessors. In this paper, we identify a small set of primitive mechanisms that are sufficiently general to be used as building blocks to solve a variety of resource-management problems. We then present STORM, a resource-management environment that embodies these mechanisms in a scalable, low-overhead, and efficient implementation. The key innovation behind STORM is a modular software architecture that reduces all resource management functionality to a small number of highly scalable mechanisms. These mechanisms simplify the integration of resource management with low-level network features. As a result of this design, STORM can launch large, parallel applications an order of magnitude faster than the best time reported in the literature and can gang-schedule a parallel application as fast as the node OS can schedule a sequential application. This paper describes the mechanisms and algorithms behind STORM and presents a detailed performance model that shows that STORM's performance can scale to thousands of nodes

Many scientific and high-performance computing applications consist of multiple processes running on different processors that communicate frequently. Because of their synchronization needs, these applications can suffer severe performance penalties if their processes are not all coscheduled to run together. Two common approaches to coscheduling jobs are batch scheduling, wherein nodes are dedicated for the duration of the run, and gang scheduling, wherein time slicing is coordinated across processors. Both work well when jobs are load-balanced and make use of the entire parallel machine. However, these conditions are rarely met and most realistic workloads consequently suffer from both internal and external fragmentation, in which resources and processors are left idle because jobs cannot be packed with perfect efficiency. This situation leads to reduced utilization and suboptimal performance. Flexible coscheduling (FCS) addresses this problem by monitoring each job's computation granularity and communication pattern and scheduling jobs based on their synchronization and load-balancing requirements. In particular, jobs that do not require stringent synchronization are identified, and are not coscheduled; instead, these processes are used to reduce fragmentation. FCS has been fully implemented on top of the STORM resource manager on a 256-processor alpha cluster and compared to batch, gang, and implicit coscheduling algorithms. This paper describes in detail the implementation of FCS and its performance evaluation with a variety of workloads, including large-scale benchmarks, scientific applications, and dynamic workloads. The experimental results show that FCS saturates at higher loads than other algorithms (up to 54 percent higher in some cases), and displays lower response times and slowdown than the other algorithms in nearly all scenarios.

Scalable management of distributed resources is one of the major challenges in deployment of large-scale clusters. Management includes transparent fault tolerance, efficient allocation of resources, and support for all the needs of parallel computing: parallel I/O, deterministic behavior, and responsiveness. Meeting these requirements with commodity hardware and operating systems is difficult because they were not designed to support global management of a large-scale system. We propose a small set of hardware mechanisms in the cluster interconnect to facilitate the implementation of a simple yet powerful global operating system. This system, inspired by concepts from the BSP and SIMD computational models, allows commodity clusters to grow to thousands of nodes while still retaining the usability and responsiveness of the single-node workstation. Our results on a software prototype show that it is possible to implement efficient and scalable system software using the proposed set of mechanisms.

Summary form only given. In the near future large-scale parallel computers will feature hundreds of thousands of processing nodes. In such systems, fault tolerance is critical as failures will occur very often. Checkpointing and rollback recovery has been extensively studied as an attempt to provide fault tolerance. However, current implementations do not provide the total transparency and full flexibility that are necessary to support the new paradigm of autonomic computing - systems able to self-heal and self-repair. We provide an in-depth evaluation of incremental checkpointing for scientific computing. The experimental results, obtained on a state-of-the art cluster running several scientific applications, show that efficient, scalable, automatic and user-transparent incremental checkpointing is within reach with current technology.

Buffered CoScheduled MPI (BCS-MPI) introduces a new approach to design the communication layer for large-scale parallel machines. The emphasis of BCS-MPI is on the global coordination of a large number of communicating processes rather than on the traditional optimization of the point-to-point performance. BCS-MPI delays the inter-processor communication in order to schedule globally the communication pattern and it is designed on top of a minimal set of collective communication primitives. In this paper we describe a prototype implementation of BCS-MPI and its communication protocols. Several experimental results, executed on a set of scientific applications, show that BCS-MPI can compete with a production-level MPI implementation, but is much simpler to implement, debug and model.

Abstract Using multiple independent networks (also known as rails) is an emerging technique which is being used to overcome bandwidth limitations and enhance fault tolerance of current high‐performance parallel computers. In this paper, we present and analyze various algorithms to allocate multiple communication rails, including static and dynamic allocation schemes. An analytical lower bound on the number of rails required for static rail allocation is shown. We also present an extensive experimental comparison of the behavior of various algorithms in terms of bandwidth and latency. We show that striping messages over multiple rails can substantially reduce network latency, depending on average message size, network load and allocation scheme. The methods compared include a static rail allocation, a basic round‐robin rail allocation, a local‐dynamic allocation based on local knowledge and a dynamic rail allocation that reserves both communication endpoints of a message before sending it. The last method is shown to perform better than the others at higher loads: up to 49% better than local‐knowledge allocation and 37% better than the round‐robin allocation. This allocation scheme also shows lower latency and it saturates at higher loads (for long enough messages). Most importantly, this proposed allocation scheme scales well with the number of rails and message size. In addition we propose a hybrid algorithm that combines the benefits of the local‐dynamic allocation for short messages with those of the dynamic algorithm for large messages. Copyright © 2003 John Wiley & Sons, Ltd.

Clusters of workstations have emerged as an important platform for building cost-effective, scalable, and highly-available computers. Although many hardware solutions are available today, the largest challenge in making largescale clusters usable lies in the system software. In this paper we present STORM, a resource management tool designed to provide scalability, low overhead, and the flexibility necessary to efficiently support and analyze a wide range of job-scheduling algorithms. STORM achieves these feats by using a small set of primitive mechanisms that are common in modern high-performance interconnects. The architecture of STORM is based on three main technical innovations. First, a part of the scheduler runs in the thread processor located on the network interface. Second, we use hardware collectives that are highly scalable both for implementing control heartbeats and to distribute the binary of a parallel job in near-constant time. Third, we use an I/O bypass protocol that allows fast data movements front the file system to the communication buffers in the network interface and vice versa. The experimental results show that STORM can launch a job with a binary of 12 MB on a 64-processor, 32-node cluster in less than 250 ms. This paper provides expert. mental and analytical evidence that these results scale to a much larger number of nodes. To the best of our knowledge, STORM significantly outperforms existing production schedulers in launching jobs, performing resource management tasks, and gang-scheduling tasks.

Although workstation clusters are a common platform for high-performance computing (HPC), they remain more difficult to manage than sequential systems or even symmetric multiprocessors. Furthermore, as cluster sizes increase, the quality of the resource-management subsystem — essentially, all of the code that runs on a cluster other than the applications — increasingly impacts application efficiency. In this paper, we present STORM, a resource-management framework designed for scalability and performance. The key innovation behind STORM is a software architecture that enables resource management to exploit low-level network features. As a result of this HPC-application-like design, STORM is orders of magnitude faster than the best reported results in the literature on two sample resource-management functions: job launching and process scheduling.

Using multiple independent networks (also known as rails) is an emerging technique to overcome bandwidth limitations and enhance fault tolerance of current high-performance clusters. We present an extensive experimental comparison of the behavior of various allocation schemes in terms of bandwidth and latency. We show that striping messages over multiple rails can substantially reduce network latency, depending on average message size, network load, and allocation scheme. The compared methods include a basic round-robin rail allocation, a local-dynamic allocation based on local knowledge, and a dynamic rail allocation that reserves both communication endpoints of a message before sending it. The last method is shown to perform better than the others at higher loads: up to 49% better than local-knowledge allocation and 37% better than the round-robin allocation. This allocation scheme also shows lower latency and it saturates on higher loads (for messages large enough). Most importantly, this proposed allocation scheme scales well with the number of rails and message sizes. In addition we propose a hybrid algorithm that combines the benefits of the local-dynamic for short messages with those of the dynamic algorithm for large messages.

The efficient implementation of collective communication patterns in a parallel machine is a challenging design effort, that requires the solution of many problems. In this paper we present an in-depth description of how the Quadrics network supports both hardware- and software-based collectives. We describe the main features of the two building blocks of this network, a network interface that can perform zero-copy user-level communication and a wormhole routing switch. We also focus our attention on the routing and flow control algorithms, deadlock avoidance and on how the processing nodes are integrated in a global, virtual shared memory. Experimental results conducted on 64-node AlphaServer cluster indicate that the time to complete the hardware-based barrier synchronization on the whole network is as low as 6 /spl mu/s, with very good scalability. Good latency and scalability are also achieved with the software-based synchronization, which takes about 15 /spl mu/s. With the broadcast, similar performance is achieved by the hardware- and software-based implementations, which can deliver messages of up to 256 bytes in 13 /spl mu/s and can get a sustained asymptotic bandwidth of 288 Mbytes/sec on all the nodes. The hardware-based barrier is almost insensitive to the network congestion, with 93% of the synchronizations taking less than 20 /spl mu/s when the network is flooded with a background traffic of unicast messages. On the other hand, the software-based implementation suffers from a significant performance degradation. With high load the hardware broadcast maintains a reasonably good latency, delivering messages up to 2KB in 200 /spl mu/s, while the software broadcast suffers from slightly higher latencies inherited from the synchronization mechanism. Both broadcast algorithms experience a significative performance degradation of the sustained bandwidth with large messages.