PGAS (UPC/Openshmem/CAF) Programming Models Through a Unified Runtime: an MVAPICH2-X Approach
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Mellanox Scalableshmem Support the Openshmem Parallel Programming Language Over Infiniband
SOFTWARE PRODUCT BRIEF Mellanox ScalableSHMEM Support the OpenSHMEM Parallel Programming Language over InfiniBand The SHMEM programming library is a one-side communications library that supports a unique set of parallel programming features including point-to-point and collective routines, synchronizations, atomic operations, and a shared memory paradigm used between the processes of a parallel programming application. SHMEM Details API defined by the OpenSHMEM.org consortium. There are two types of models for parallel The library works with the OpenFabrics RDMA programming. The first is the shared memory for Linux stack (OFED), and also has the ability model, in which all processes interact through a to utilize Mellanox Messaging libraries (MXM) globally addressable memory space. The other as well as Mellanox Fabric Collective Accelera- HIGHLIGHTS is a distributed memory model, in which each tions (FCA), providing an unprecedented level of FEATURES processor has its own memory, and interaction scalability for SHMEM programs running over – Use of symmetric variables and one- with another processors memory is done though InfiniBand. sided communication (put/get) message communication. The PGAS model, The use of Mellanox FCA provides for collective – RDMA for performance optimizations or Partitioned Global Address Space, uses a optimizations by taking advantage of the high for one-sided communications combination of these two methods, in which each performance features within the InfiniBand fabric, – Provides shared memory data transfer process has access to its own private memory, including topology aware coalescing, hardware operations (put/get), collective and also to shared variables that make up the operations, and atomic memory multicast and separate quality of service levels for global memory space. -
Scalable and Distributed Deep Learning (DL): Co-Design MPI Runtimes and DL Frameworks
Scalable and Distributed Deep Learning (DL): Co-Design MPI Runtimes and DL Frameworks OSU Booth Talk (SC ’19) Ammar Ahmad Awan [email protected] Network Based Computing Laboratory Dept. of Computer Science and Engineering The Ohio State University Agenda • Introduction – Deep Learning Trends – CPUs and GPUs for Deep Learning – Message Passing Interface (MPI) • Research Challenges: Exploiting HPC for Deep Learning • Proposed Solutions • Conclusion Network Based Computing Laboratory OSU Booth - SC ‘18 High-Performance Deep Learning 2 Understanding the Deep Learning Resurgence • Deep Learning (DL) is a sub-set of Machine Learning (ML) – Perhaps, the most revolutionary subset! Deep Machine – Feature extraction vs. hand-crafted Learning Learning features AI Examples: • Deep Learning Examples: Logistic Regression – A renewed interest and a lot of hype! MLPs, DNNs, – Key success: Deep Neural Networks (DNNs) – Everything was there since the late 80s except the “computability of DNNs” Adopted from: http://www.deeplearningbook.org/contents/intro.html Network Based Computing Laboratory OSU Booth - SC ‘18 High-Performance Deep Learning 3 AlexNet Deep Learning in the Many-core Era 10000 8000 • Modern and efficient hardware enabled 6000 – Computability of DNNs – impossible in the 4000 ~500X in 5 years 2000 past! Minutesto Train – GPUs – at the core of DNN training 0 2 GTX 580 DGX-2 – CPUs – catching up fast • Availability of Datasets – MNIST, CIFAR10, ImageNet, and more… • Excellent Accuracy for many application areas – Vision, Machine Translation, and -
Parallel Programming
Parallel Programming Parallel Programming Parallel Computing Hardware Shared memory: multiple cpus are attached to the BUS all processors share the same primary memory the same memory address on different CPU’s refer to the same memory location CPU-to-memory connection becomes a bottleneck: shared memory computers cannot scale very well Parallel Programming Parallel Computing Hardware Distributed memory: each processor has its own private memory computational tasks can only operate on local data infinite available memory through adding nodes requires more difficult programming Parallel Programming OpenMP versus MPI OpenMP (Open Multi-Processing): easy to use; loop-level parallelism non-loop-level parallelism is more difficult limited to shared memory computers cannot handle very large problems MPI(Message Passing Interface): require low-level programming; more difficult programming scalable cost/size can handle very large problems Parallel Programming MPI Distributed memory: Each processor can access only the instructions/data stored in its own memory. The machine has an interconnection network that supports passing messages between processors. A user specifies a number of concurrent processes when program begins. Every process executes the same program, though theflow of execution may depend on the processors unique ID number (e.g. “if (my id == 0) then ”). ··· Each process performs computations on its local variables, then communicates with other processes (repeat), to eventually achieve the computed result. In this model, processors pass messages both to send/receive information, and to synchronize with one another. Parallel Programming Introduction to MPI Communicators and Groups: MPI uses objects called communicators and groups to define which collection of processes may communicate with each other. -
Introduction to Parallel Programming
Introduction to Parallel Programming Martin Čuma Center for High Performance Computing University of Utah [email protected] Overview • Types of parallel computers. • Parallel programming options. • How to write parallel applications. • How to compile. • How to debug/profile. • Summary, future expansion. 3/13/2009 http://www.chpc.utah.edu Slide 2 Parallel architectures Single processor: • SISD – single instruction single data. Multiple processors: • SIMD - single instruction multiple data. • MIMD – multiple instruction multiple data. Shared Memory Distributed Memory 3/13/2009 http://www.chpc.utah.edu Slide 3 Shared memory Dual quad-core node • All processors have BUS access to local memory CPU Memory • Simpler programming CPU Memory • Concurrent memory access Many-core node (e.g. SGI) • More specialized CPU Memory hardware BUS • CHPC : CPU Memory Linux clusters, 2, 4, 8 CPU Memory core nodes CPU Memory 3/13/2009 http://www.chpc.utah.edu Slide 4 Distributed memory • Process has access only BUS CPU to its local memory Memory • Data between processes CPU Memory must be communicated • More complex Node Network Node programming Node Node • Cheap commodity hardware Node Node • CHPC: Linux clusters Node Node (Arches, Updraft) 8 node cluster (64 cores) 3/13/2009 http://www.chpc.utah.edu Slide 5 Parallel programming options Shared Memory • Threads – POSIX Pthreads, OpenMP – Thread – own execution sequence but shares memory space with the original process • Message passing – processes – Process – entity that executes a program – has its own -
An Open Standard for SHMEM Implementations Introduction
OpenSHMEM: An Open Standard for SHMEM Implementations Introduction • OpenSHMEM is an effort to create a standardized SHMEM library for C , C++, and Fortran • OpenSHMEM is a Partitioned Global Address Space (PGAS) library and supports Single Program Multiple Data (SPMD) style of programming • SGI’s SHMEM API is the baseline for OpenSHMEM Specification 1.0 • One-sided communication is achieved through Symmetric variables • globals C/C++: Non-stack variables Fortran: objects in common blocks or with the SAVE attribute • dynamically allocated and managed by the OpenSHMEM Library Figure 1. Dynamic allocation of symmetric variable ‘x’ OpenSHMEM API • OpenSHMEM Specification 1.0 provides support for data transfer operations, collective and point- to-point synchronization mechanisms (barrier, fence, quiet, wait), collective operations (broadcast, collection, reduction), atomic memory operations (swap, fetch/add, increment), and distributed locks. • Open to the community for reviews and contributions. Current Status • University of Houston has developed a portable reference OpenSHMEM library. • OpenSHMEM Specification 1.0 man pages are available. • OpenSHMEM mailing list for discussions and contributions can be joined by emailing [email protected] • Website for OpenSHMEM and a Wiki for community use are available. Figure 2. University of Houston http://www.openshmem.org/ Implementation Future Work and Goals • Develop OpenSHMEM Specification 2.0 with co-operation and contribution from the OpenSHMEM community • Discuss and extend specification with important new capabilities • Improve on the OpenSHMEM reference implementation by providing support for scalable collective algorithms • Explore innovative hardware platforms . -
Parallel Computer Architecture
Parallel Computer Architecture Introduction to Parallel Computing CIS 410/510 Department of Computer and Information Science Lecture 2 – Parallel Architecture Outline q Parallel architecture types q Instruction-level parallelism q Vector processing q SIMD q Shared memory ❍ Memory organization: UMA, NUMA ❍ Coherency: CC-UMA, CC-NUMA q Interconnection networks q Distributed memory q Clusters q Clusters of SMPs q Heterogeneous clusters of SMPs Introduction to Parallel Computing, University of Oregon, IPCC Lecture 2 – Parallel Architecture 2 Parallel Architecture Types • Uniprocessor • Shared Memory – Scalar processor Multiprocessor (SMP) processor – Shared memory address space – Bus-based memory system memory processor … processor – Vector processor bus processor vector memory memory – Interconnection network – Single Instruction Multiple processor … processor Data (SIMD) network processor … … memory memory Introduction to Parallel Computing, University of Oregon, IPCC Lecture 2 – Parallel Architecture 3 Parallel Architecture Types (2) • Distributed Memory • Cluster of SMPs Multiprocessor – Shared memory addressing – Message passing within SMP node between nodes – Message passing between SMP memory memory nodes … M M processor processor … … P … P P P interconnec2on network network interface interconnec2on network processor processor … P … P P … P memory memory … M M – Massively Parallel Processor (MPP) – Can also be regarded as MPP if • Many, many processors processor number is large Introduction to Parallel Computing, University of Oregon, -
Parallel Programming Using Openmp Feb 2014
OpenMP tutorial by Brent Swartz February 18, 2014 Room 575 Walter 1-4 P.M. © 2013 Regents of the University of Minnesota. All rights reserved. Outline • OpenMP Definition • MSI hardware Overview • Hyper-threading • Programming Models • OpenMP tutorial • Affinity • OpenMP 4.0 Support / Features • OpenMP Optimization Tips © 2013 Regents of the University of Minnesota. All rights reserved. OpenMP Definition The OpenMP Application Program Interface (API) is a multi-platform shared-memory parallel programming model for the C, C++ and Fortran programming languages. Further information can be found at http://www.openmp.org/ © 2013 Regents of the University of Minnesota. All rights reserved. OpenMP Definition Jointly defined by a group of major computer hardware and software vendors and the user community, OpenMP is a portable, scalable model that gives shared-memory parallel programmers a simple and flexible interface for developing parallel applications for platforms ranging from multicore systems and SMPs, to embedded systems. © 2013 Regents of the University of Minnesota. All rights reserved. MSI Hardware • MSI hardware is described here: https://www.msi.umn.edu/hpc © 2013 Regents of the University of Minnesota. All rights reserved. MSI Hardware The number of cores per node varies with the type of Xeon on that node. We define: MAXCORES=number of cores/node, e.g. Nehalem=8, Westmere=12, SandyBridge=16, IvyBridge=20. © 2013 Regents of the University of Minnesota. All rights reserved. MSI Hardware Since MAXCORES will not vary within the PBS job (the itasca queues are split by Xeon type), you can determine this at the start of the job (in bash): MAXCORES=`grep "core id" /proc/cpuinfo | wc -l` © 2013 Regents of the University of Minnesota. -
Enabling Efficient Use of UPC and Openshmem PGAS Models on GPU Clusters
Enabling Efficient Use of UPC and OpenSHMEM PGAS Models on GPU Clusters Presented at GTC ’15 Presented by Dhabaleswar K. (DK) Panda The Ohio State University E-mail: [email protected] hCp://www.cse.ohio-state.edu/~panda Accelerator Era GTC ’15 • Accelerators are becominG common in hiGh-end system architectures Top 100 – Nov 2014 (28% use Accelerators) 57% use NVIDIA GPUs 57% 28% • IncreasinG number of workloads are beinG ported to take advantage of NVIDIA GPUs • As they scale to larGe GPU clusters with hiGh compute density – hiGher the synchronizaon and communicaon overheads – hiGher the penalty • CriPcal to minimize these overheads to achieve maximum performance 3 Parallel ProGramminG Models Overview GTC ’15 P1 P2 P3 P1 P2 P3 P1 P2 P3 LoGical shared memory Shared Memory Memory Memory Memory Memory Memory Memory Shared Memory Model Distributed Memory Model ParPPoned Global Address Space (PGAS) DSM MPI (Message PassinG Interface) Global Arrays, UPC, Chapel, X10, CAF, … • ProGramminG models provide abstract machine models • Models can be mapped on different types of systems - e.G. Distributed Shared Memory (DSM), MPI within a node, etc. • Each model has strenGths and drawbacks - suite different problems or applicaons 4 Outline GTC ’15 • Overview of PGAS models (UPC and OpenSHMEM) • Limitaons in PGAS models for GPU compuPnG • Proposed DesiGns and Alternaves • Performance Evaluaon • ExploiPnG GPUDirect RDMA 5 ParPPoned Global Address Space (PGAS) Models GTC ’15 • PGAS models, an aracPve alternave to tradiPonal message passinG - Simple -
An Overview of the PARADIGM Compiler for Distributed-Memory
appeared in IEEE Computer, Volume 28, Number 10, October 1995 An Overview of the PARADIGM Compiler for DistributedMemory Multicomputers y Prithvira j Banerjee John A Chandy Manish Gupta Eugene W Ho dges IV John G Holm Antonio Lain Daniel J Palermo Shankar Ramaswamy Ernesto Su Center for Reliable and HighPerformance Computing University of Illinois at UrbanaChampaign W Main St Urbana IL Phone Fax banerjeecrhcuiucedu Abstract Distributedmemory multicomputers suchasthetheIntel Paragon the IBM SP and the Thinking Machines CM oer signicant advantages over sharedmemory multipro cessors in terms of cost and scalability Unfortunately extracting all the computational p ower from these machines requires users to write ecientsoftware for them which is a lab orious pro cess The PARADIGM compiler pro ject provides an automated means to parallelize programs written using a serial programming mo del for ecient execution on distributedmemory multicomput ers In addition to p erforming traditional compiler optimizations PARADIGM is unique in that it addresses many other issues within a unied platform automatic data distribution commu nication optimizations supp ort for irregular computations exploitation of functional and data parallelism and multithreaded execution This pap er describ es the techniques used and pro vides exp erimental evidence of their eectiveness on the Intel Paragon the IBM SP and the Thinking Machines CM Keywords compilers distributed memorymulticomputers parallelizing compilers parallel pro cessing This research was supp orted -
Concepts from High-Performance Computing Lecture a - Overview of HPC Paradigms
Concepts from High-Performance Computing Lecture A - Overview of HPC paradigms OBJECTIVE: The clock speeds of computer processors are topping out as the limits of traditional computer chip technology are being reached. Increased performance is being achieved by increasing the number of compute cores on a chip. In order to understand and take advantage of this disruptive technology, one must appreciate the paradigms of high-performance computing. The economics of technology Technology is governed by economics. The rate at which a computer processor can execute instructions (e.g., floating-point operations) is proportional to the frequency of its clock. However, 2 power ∼ (voltage) × (frequency), voltage ∼ frequency, 3 =⇒ power ∼ (frequency) e.g., a 50% increase in performance by increasing frequency requires 3.4 times more power. By going to 2 cores, this performance increase can be achieved with 16% less power1. 1This assumes you can make 100% use of each core. Moreover, transistors are getting so small that (undesirable) quantum effects (such as electron tunnelling) are becoming non-negligible. → Increasing frequency is no longer an option! When increasing frequency was possible, software got faster because hardware got faster. In the near future, the only software that will survive will be that which can take advantage of parallel processing. It is already difficult to do leading-edge computational science without parallel computing; this situation can only get worse. Computational scientists who ignore parallel computing do so at their own risk! Most of numerical analysis (and software in general) was designed for the serial processor. There is a lot of numerical analysis that needs to be revisited in this new world of computing. -
In Reference to RPC: It's Time to Add Distributed Memory
In Reference to RPC: It’s Time to Add Distributed Memory Stephanie Wang, Benjamin Hindman, Ion Stoica UC Berkeley ACM Reference Format: D (e.g., Apache Spark) F (e.g., Distributed TF) Stephanie Wang, Benjamin Hindman, Ion Stoica. 2021. In Refer- A B C i ii 1 2 3 ence to RPC: It’s Time to Add Distributed Memory. In Workshop RPC E on Hot Topics in Operating Systems (HotOS ’21), May 31-June 2, application 2021, Ann Arbor, MI, USA. ACM, New York, NY, USA, 8 pages. Figure 1: A single “application” actually consists of many https://doi.org/10.1145/3458336.3465302 components and distinct frameworks. With no shared address space, data (squares) must be copied between 1 Introduction different components. RPC has been remarkably successful. Most distributed ap- Load balancer Scheduler + Mem Mgt plications built today use an RPC runtime such as gRPC [3] Executors or Apache Thrift [2]. The key behind RPC’s success is the Servers request simple but powerful semantics of its programming model. client data request cache In particular, RPC has no shared state: arguments and return Distributed object store values are passed by value between processes, meaning that (a) (b) they must be copied into the request or reply. Thus, argu- ments and return values are inherently immutable. These Figure 2: Logical RPC architecture: (a) today, and (b) with a shared address space and automatic memory management. simple semantics facilitate highly efficient and reliable imple- mentations, as no distributed coordination is required, while then return a reference, i.e., some metadata that acts as a remaining useful for a general set of distributed applications. -
Parallel Breadth-First Search on Distributed Memory Systems
Parallel Breadth-First Search on Distributed Memory Systems Aydın Buluç Kamesh Madduri Computational Research Division Lawrence Berkeley National Laboratory Berkeley, CA {ABuluc, KMadduri}@lbl.gov ABSTRACT tions, in these graphs. To cater to the graph-theoretic anal- Data-intensive, graph-based computations are pervasive in yses demands of emerging \big data" applications, it is es- several scientific applications, and are known to to be quite sential that we speed up the underlying graph problems on challenging to implement on distributed memory systems. current parallel systems. In this work, we explore the design space of parallel algo- We study the problem of traversing large graphs in this rithms for Breadth-First Search (BFS), a key subroutine in paper. A traversal refers to a systematic method of explor- several graph algorithms. We present two highly-tuned par- ing all the vertices and edges in a graph. The ordering of allel approaches for BFS on large parallel systems: a level- vertices using a \breadth-first" search (BFS) is of particular synchronous strategy that relies on a simple vertex-based interest in many graph problems. Theoretical analysis in the partitioning of the graph, and a two-dimensional sparse ma- random access machine (RAM) model of computation indi- trix partitioning-based approach that mitigates parallel com- cates that the computational work performed by an efficient munication overhead. For both approaches, we also present BFS algorithm would scale linearly with the number of ver- hybrid versions with intra-node multithreading. Our novel tices and edges, and there are several well-known serial and hybrid two-dimensional algorithm reduces communication parallel BFS algorithms (discussed in Section2).