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Machine learning is widely used in our daily lives. Large amounts of data have been continuously produced and transmitted to the cloud for model training and data processing, which raises a problem: how to preserve the security of the data. Recently, a secure machine learning system named SecureML has been proposed to solve this issue using two-party computation. However, due to the excessive computation expenses of two-party computation, the secure machine learning is about 2× slower than the original machine learning methods. Previous work on secure machine learning mostly focused on novel protocols or improving accuracy, while the performance metric has been ignored. In this article, we propose a GPU-based framework ParSecureML to improve the performance of secure machine learning algorithms based on two-party computation. The main challenges of developing ParSecureML lie in the complex computation patterns, frequent intra-node data transmission between CPU and GPU, and complicated inter-node data dependence. To handle these challenges, we propose a series of novel solutions, including profiling-guided adaptive GPU utilization, fine-grained double pipeline for intra-node CPU-GPU cooperation, and compressed transmission for inter-node communication. Moreover, we integrate architecture specific optimizations, such as Tensor Cores, into ParSecureML. As far as we know, this is the first GPU-based secure machine learning framework. Compared to the state-of-the-art framework, ParSecureML achieves an average of 33.8× speedup. ParSecureML can also be applied to inferences, which achieves 31.7× speedup on average.

There has been a remarkable increase in the speed of AI development over the past few years. Artificial intelligence and deep learning techniques are blooming and expanding in all forms to every sector possible. With the emerging intelligent autonomous navigation systems, both memory allocation and data movement are becoming the main bottlenecks in inter-process communication procedures, especially in supporting various types of messages between multiple programming languages. To reduce significant memory allocation and data movement cost, we propose a novel memory-centric mechanism, which includes a virtual layer based architecture and a pre-record memory allocation algorithm. Furthermore, we implement a memory-centric communication framework named Z-framework based on the proposed mechanism to achieve high efficient IPC procedures in autonomous navigation systems. Experimental results show that Z-framework is able to gain up to 41% and 35% performance improvement compared with the approach used in ROS2, which is an industry standard and the state-of-the-art approach used in CyberRT, respectively.

Machine learning has been widely used in our daily lives. Large amounts of data have been continuously produced and transmitted to the cloud for model training and data processing, which raises a problem: how to preserve the security of the data. Recently, a secure machine learning system named SecureML has been proposed to solve this issue using two-party computation. However, due to the excessive computation expenses of two-party computation, the secure machine learning is about 2x slower than the original machine learning methods. Previous work on secure machine learning mostly focused on novel protocols or improving accuracy, while the performance metric has been ignored. In this paper, we propose a GPU-based framework ParSecureML to improve the performance of secure machine learning algorithms based on two-party computation. The main challenges of developing ParSecureML lie in the complex computation patterns, frequent intra-node data transmission between CPU and GPU, and complicated inter-node data dependence. To handle these challenges, we propose a series of novel solutions, including profiling-guided adaptive GPU utilization, fine-grained double pipeline for intra-node CPU-GPU cooperation, and compressed transmission for inter-node communication. As far as we know, this is the first GPU-based secure machine learning framework. Compared to the state-of-the-art framework, ParSecureML achieves an average of 32.2x speedup. ParSecureML can be downloaded from https://github.com/ZhengChenCS/ParSecureML.

Scaling a parallel program to modern supercomputers is challenging due to inter-process communication, code serialization, and resource contention. Performance analysis tools for finding such scaling bottlenecks either base on profiling or tracing. Profiling incurs lower overheads but does not capture detailed dependencies needed for root-cause analyses. Tracing collects all information at prohibitive overheads. In this work, we develop ScalAna that uses static analysis techniques to achieve the best of both worlds---it enables the analyzability of traces at a cost similar to profiling. We leverage compiler and runtime lightweight techniques to generate performance graph and perform graph analysis algorithm to detect the root cause of scaling issues. We evaluate ScalAna with real applications on the Tianhe-2 supercomputer. Results show that our approach can effectively locate the root cause of scalability bottlenecks for real applications and incur less than 6.38% overhead (1.89% on average) for up to 2,048 processes.

Scaling a parallel program to modern supercomputers is challenging due to inter-process communication, Amdahl's law, and resource contention. Performance analysis tools for finding such scaling bottlenecks either base on profiling or tracing. Profiling incurs low overheads but does not capture detailed dependencies needed for root-cause analysis. Tracing collects all information at prohibitive overheads. In this work, we design SCALANA that uses static analysis techniques to achieve the best of both worlds - it enables the analyzability of traces at a cost similar to profiling. SCALANA first leverages static compiler techniques to build a Program Structure Graph, which records the main computation and communication patterns as well as the program's control structures. At runtime, we adopt lightweight techniques to collect performance data according to the graph structure and generate a Program Performance Graph. With this graph, we propose a novel approach, called backtracking root cause detection, which can automatically and efficiently detect the root cause of scaling loss. We evaluate SCALANA with real applications. Results show that our approach can effectively locate the root cause of scaling loss for real applications and incurs 1.73parcent overhead on average for up to 2,048 processes. We achieve up to 11.11parcent performance improvement by fixing the root causes detected by SCALANA on 2,048 processes. © 2020 IEEE, SC20: International Conference for High Performance Computing, Networking, Storage and Analysis, ISBN:978-1-7281-9998-6, ISBN:978-1-7281-9999-3

Graph Neural Network (GNN) has recently drawn a rapid increase of interest in many domains for its effectiveness in learning over graphs. Maximizing its performance is essential for many tasks, but remains preliminarily understood. In this work, we provide an in-depth examination of the state-of-the-art GNN frameworks, revealing five major gaps in the current frameworks in optimizing GNN performance, especially in handling the special complexities of GNN over traditional graph or DNN operations. Based on the insights, we put together a set of optimizations to fill the gaps. These optimizations leverage the state-of-the-art GPU optimization techniques and tailor them to the special properties of GNN. Experimental results show that these optimizations achieve 1.37×--15.5× performance improvement over the state-of-the-art frameworks on various GNN models.

Performance variance becomes increasingly challenging on current large-scale HPC systems. Even using a fixed number of computing nodes, the execution time of several runs can vary significantly. Many parallel programs executing on supercomputers suffer from such variance. Performance variance not only causes unpredictable performance requirement violations, but also makes it unintuitive to understand the program behavior. Despite prior efforts, efficient on-line detection of performance variance remains an open problem. In this paper, we propose vS ensor , a novel approach for light-weight and on-line performance variance detection. The key insight is that, instead of solely relying on an external detector, the source code of a program itself could reveal the runtime performance characteristics. Specifically, many parallel programs contain code snippets that are executed repeatedly with an invariant quantity of work. Based on this observation, we use compiler techniques to automatically identify these fixed-workload snippets and use them as performance variance sensors (v-sensors) that enable effective detection. We evaluate vS ensor with a variety of parallel programs on the Tianhe-2 system. Results show that vS ensor can effectively detect performance variance on HPC systems. The performance overhead is smaller than 4% with up to 16,384 processes. In particular, with vS ensor , we found a bad node with slow memory that slowed a program's performance by 21%. As a showcase, we also detected a severe network performance problem that caused a 3.37X slowdown for an HPC kernel program on the Tianhe-2 system.

Traditional batch job schedulers adopt the Compact-n-Exclusive (CE) strategy, packing processes of a parallel job into as few compute nodes as possible. While CE minimizes inter-node network communication, it often brings self-contention among tasks of a resource-intensive application. Recent studies have used virtual containers to balance CPU utilization and memory capacity across physical nodes, but the imbalance in cache and memory bandwidth usage is still under-investigated. In this work, we propose Spread-n-Share (SNS): a new batch scheduling strategy that automatically scales resource-bound applications out onto more nodes to alleviate their performance bottleneck, and co-locate jobs in a resource compatible manner. We implement Uberun, a prototype scheduler to validate SNS, considering shared-cache capacity and memory bandwidth as two types of performance-critical shared resources. Experimental results using 12 diverse cluster workloads show that SNS improves the overall system throughput by 19.8% on average over CE, while achieving an average individual job speedup of 1.8%.

Pipeline is a parallel computing model underpinning a class of important applications running on CPU-GPU heterogeneous systems. A critical aspect for the efficiency of such applications is the support of communications among pipeline stages that may reside on CPU and different parts of a GPU. Existing libraries of concurrent data structures do not meet the needs, due to the massive parallelism on GPU and the complexities in CPU-GPU memory and connections. This work gives an in-depth study on the communication problem. It identifies three key issues, namely, slow and error-prone detection of the end of pipeline processing, intensive queue contentions on GPU, and cumbersome inter-device data movements. This work offers solutions to each of the issues, and integrates all together to form a unified library named HiWayLib. Experiments show that HiWayLib significantly boosts the efficiency of pipeline communications in CPU-GPU heterogeneous applications. For real-world applications, HiWayLib produces 1.22~2.13× speedups over the state-of-art implementations with little extra programming effort required.

Recent studies have shown promising performance benefits when multiple stages of a pipelined stencil application are mapped to different parts of a GPU to run concurrently. An important factor for the computing efficiency of such pipelines is the granularity of a task. In previous programming frameworks that support true pipelined computations on GPU, the choice has to be made by the programmers during the application development time. Due to many difficulties, programmers' decisions are often far from optimal, causing inferior performance and performance portability. This paper presents GOPipe, a granularity-oblivious programming framework for efficient pipelined stencil executions on GPU. With GOPipe, programmers no longer need to specify the appropriate task granularity. GOPipe automatically finds it, and dynamically schedules tasks of that granularity for efficiency while observing all inter-task and inter-stage data dependencies. In our experiments on six real-life applications and various scenarios, GOPipe outperforms the state-of-the-art system by 1.39X on average with a much better programming productivity.

Recent studies have found cloud environments increasingly appealing for executing HPC applications, including tightly coupled parallel simulations. At the same time, while public clouds offer elastic, on-demand resource provisioning and pay-as-you-go pricing, individual users setting up their on-demand virtual clusters may not be able to take full advantage of common cost-saving opportunities, such as reserved instances. In this paper, we propose a Semi-Elastic Cluster (SEC) computing model for organizations to reserve and dynamically resize a virtual cloud-based cluster. We present a set of integrated batch scheduling plus resource scaling strategies uniquely enabled by SEC, as well as an online reserved instance provisioning algorithm based on job history. Our trace-driven simulation results show that such a model has a 61.0 percent cost saving than individual users acquiring and managing cloud resources without causing longer average job wait time. Moreover, to exploit the advantages of different public clouds, we also extend SEC to a multi-cloud environment, where SEC can get a lower cost than on any single cloud. We design and implement a prototype system of the SEC model and evaluate it in terms of management overhead and average job wait time. Experimental results show that the management overhead is negligible with respect to the job wait time.

Traditionally, complex engineering applications (CEAs), which consist of numerous components (software) and require a large amount of computing resources, usually run in dedicated clusters or high performance computing (HPC) centers. Nowadays, Cloud computing system with the ability of providing massive computing resources and customizable execution environment is becoming an attractive option for CEAs. As a new type on Cloud applications, CEA also brings the challenges of dealing with Cloud resources. In this paper, we provide a comprehensive survey of Cloud resource management research for CEAs. The survey puts forward two important questions: 1) what are the main challenges for CEAs to run in Clouds? and 2) what are the prior research topics addressing these challenges? We summarize and highlight the main challenges and prior research topics. Our work can be probably helpful to those scientists and engineers who are interested in running CEAs in Cloud environment.

Today's rapidly growing document volumes pose pressing challenges to modern document analytics frameworks, in both space usage and processing time. Recently, a promising method, called text analytics directly on compressed data (TADOC), was proposed for improving both the time and space efficiency of text analytics. The main idea of the technique is to enable direct document analytics on compressed data. This paper focuses on the programming challenges for developing efficient TADOC programs. It presents Zwift, the first programming framework for TADOC, which consists of a Domain Specific Language, a compiler and runtime, and a utility library. Experiments show that Zwift significantly improves programming productivity, while effectively unleashing the power of TADOC, producing code that reduces storage usage by 90.8% and execution time by 41.0% on six text analytics problems.

Recently, various applications including data analytics and machine learning have been developed for geo-distributed cloud data centers. For those applications, the ways to map parallel processes to physical nodes (i.e., "process mapping") could significantly impact the performance of the applications because of non-uniform communication cost in such geo-distributed environments. While process mapping has been widely studied in grid/cluster environments, few of the existing studies have considered the problem in geo-distributed cloud environments. In this paper, we propose a novel model to formulate the geo-distributed process mapping problem and develop a new method to efficiently find the near optimal solution. Our algorithm considers both the network communication performance of geo-distributed data centers as well as the communication matrix of the target application. Evaluation results with real experiments on Amazon EC2 and simulations demonstrate that our proposal achieves significant performance improvement (50% on average) compared to the state-of-the-art algorithms.

Pipeline is an important programming pattern, while GPU, designed mostly for data-level parallel executions, lacks an efficient mechanism to support pipeline programming and executions. This paper provides a systematic examination of various existing pipeline execution models on GPU, and analyzes their strengths and weaknesses. To address their shortcomings, this paper then proposes three new execution models equipped with much improved controllability, including a hybrid model that is capable of getting the strengths of all. These insights ultimately lead to the development of a software programming framework named VersaPipe. With VersaPipe, users only need to write the operations for each pipeline stage. VersaPipe will then automatically assemble the stages into a hybrid execution model and configure it to achieve the best performance. Experiments on a set of pipeline benchmarks and a real-world face detection application show that VersaPipe produces up to $6.90 \times (2.88 \times$ on average) speedups over the original manual implementations. CCS CONCEPTS • General and reference $\rightarrow$ Performance; • Computing methodologies $\rightarrow$ Parallel computing methodologies; • Computer systems organization $\rightarrow$ Heterogeneous (hybrid) systems

Recent studies have found cloud environments increasingly appealing for executing HPC applications, including tightly coupled parallel simulations. While public clouds offer elastic, on-demand resource provisioning and pay-as-you-go pricing, individual users setting up their on-demand virtual clusters may not be able to take full advantage of common cost-saving opportunities, such as reserved instances. In this paper, we propose a Semi-Elastic Cluster (SEC) computing model for organizations to reserve and dynamically resize a virtual cloud-based cluster. We present a set of integrated batch scheduling plus resource scaling strategies uniquely enabled by SEC, as well as an online reserved instance provisioning algorithm based on job history. Our trace-driven simulation results show that such a model has a 61.0% cost saving than individual users acquiring and managing cloud resources without causing longer average job wait time. Meanwhile, the overhead of acquiring/maintaining shared cloud instances is shown to take only a few seconds.

The FCFS-based backfill algorithm is widely used in scheduling high-performance computer systems. The algorithm relies on runtime estimate of jobs which is provided by users. However, statistics show the accuracy of user-provided estimate is poor. Users are very likely to provide a much longer runtime estimate than its real execution time.

The emergence of cloud services brings new possibilities for constructing and using HPC platforms. However, while cloud services provide the flexibility and convenience of customized, pay-as-you-go parallel computing, multiple previous studies in the past three years have indicated that cloud-based clusters need a significant performance boost to become a competitive choice, especially for tightly coupled parallel applications. In this work, we examine the feasibility of running HPC applications in clouds. This study distinguishes itself from existing investigations in several ways: 1) We carry out a comprehensive examination of issues relevant to the HPC community, including performance, cost, user experience, and range of user activities. 2) We compare an Amazon EC2-based platform built upon its newly available HPC-oriented virtual machines with typical local cluster and supercomputer options, using benchmarks and applications with scale and problem size unprecedented in previous cloud HPC studies. 3) We perform detailed performance and scalability analysis to locate the chief limiting factors of the state-of-the-art cloud based clusters. 4) We present a case study on the impact of per-application parallel I/O system configuration uniquely enabled by cloud services. Our results reveal that though the scalability of EC2-based virtual clusters still lags behind traditional HPC alternatives, they are rapidly gaining in overall performance and cost-effectiveness, making them feasible candidates for performing tightly coupled scientific computing. In addition, our detailed benchmarking and profiling discloses and analyzes several problems regarding the performance and performance stability on EC2.

There is a trend to migrate HPC (High Performance Computing) applications to cloud platforms, such as the Amazon EC2 Cluster Compute Instances (CCIs). While existing research has mainly focused on the performance impact of virtualized environments and interconnect technologies on parallel programs, we suggest that the configurability enabled by clouds is another important dimension to explore.Unlike on traditional HPC platforms, on a cloud-resident virtual cluster it is easy to change the I/O configurations, such as the choice of file systems, the number of I/O nodes, and the types of virtual disks, to fit the I/O requirements of different applications. In this paper, we discuss how cloud platforms can be employed to form customized and balanced I/O subsystems for individual I/O-intensive MPI applications. Through our preliminary evaluation, we demonstrate that different applications will benefit from individually tailored I/O system configurations. For a given I/O-intensive application, different I/O settings may lead to significant overall application performance or cost difference (up to 2.5-fold). Our exploration indicates that customized system configuration for HPC applications in the cloud is important and non-trivial.

International audience; Xen is one of the most popular virtualization platforms nowadays, which has been broadly used by the industry. Credit scheduler, the default scheduler of Xen, was initially designed for serial jobs, which achieves good performance overall for serial jobs. Unfortunately, the parallel jobs are likely to co-exist with serial jobs in the same host in practice, the resource contention between virtual machines results in severe performance degradation of the parallel jobs. In this paper, we propose vGrouper, a progressive solution to enhance the performance of the parallel jobs. The vGrouper focuses on synchronizing the execution time of the parallel nodes in order to achieve the best performance of the parallel job. Moreover, the vGrouper guarantees that the parallel job nodes are able to run concurrently on pCPUs for the entire time slice, which maximizes the efficiency of communication between parallel nodes. A prototype of vGrouper is implemented, the experimental results demonstrate that the performance of the parallel job and resource utilization in Xen have been significantly improved.

International audience; The training process of a neural network is the most time-consuming procedure before being deployed to applications. In this paper, we investigate the loss trend of the training data during the training process. We find that given a fixed set of hyper-parameters, pruning specific types of training data can reduce the time consumption of the training process while maintaining the accuracy of the neural network. We developed a data fine-pruning approach, which can monitor and analyse the loss trend of training instances at real-time, and based on the analysis results, temporarily pruned specific instances during the training process basing on the analysis. Furthermore, we formulate the time consumption reduced by applying our data fine-pruning approach. Extensive experiments with different neural networks are conducted to verify the effectiveness of our method. The experimental results show that applying the data fine-pruning approach can reduce the training time by around 14.29% while maintaining the accuracy of the neural network.