Advanced Computer Architecture
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Pipelining 2
Instruction-Level Parallelism Dynamic Scheduling CS448 1 Dynamic Scheduling • Static Scheduling – Compiler rearranging instructions to reduce stalls • Dynamic Scheduling – Hardware rearranges instruction stream to reduce stalls – Possible to account for dependencies that are only known at run time - e. g. memory reference – Simplifies the compiler – Code built for one pipeline in mind could also run efficiently on a different pipeline – minimizes the need for speculative slot filling - NP hard • Once a common tactic with supercomputers and mainframes but was too expensive for single-chip – Now fits on a desktop PC’s 2 1 Dynamic Scheduling • Dependencies that are close together stall the entire pipeline – DIVD F0, F2, F4 – ADDD F10, F0, F8 – SUBD F12, F8, F14 • The ADD needs the DIV to finish, so there is a stall… which also stalls the SUBD – Looong stall for DIV – But the SUBD is independent so there is no reason why we shouldn’t execute it – Or is there? • Precise Interrupts - Ignore for now • Compiler could rearrange instructions, but so could the hardware 3 Dynamic Scheduling • It would be desirable to decode instructions into the pipe in order but then let them stall individually while waiting for operands before issue to execution units. • Dynamic Scheduling – Out of Order Issue / Execution • Scoreboarding 4 2 Scoreboarding Split ID stage into two: Issue (Decode, check for Structural hazards) Read Operands (Wait until no data hazards, read operands) 5 Scoreboard Overview • Consider another example: – DIVD F0, F2, F4 – ADDD F10, F0, -
And Complex-Valued Multiply-Accumulate SIMD Unit for Digital Signal Processors
An Area Efficient Real- and Complex-Valued Multiply-Accumulate SIMD Unit for Digital Signal Processors Lukas Gerlach, Guillermo Paya-Vay´ a,´ and Holger Blume Cluster of Excellence Hearing4all, Institute of Microelectronic Systems Leibniz Universitat¨ Hannover, Appelstr. 4, 30167 Hannover, Germany Email: {gerlach, guipava, blume}@ims.uni-hannover.de Abstract—This paper explores a real- and complex-valued In the signal processing field, the fast Fourier transform multiply-accumulate (MAC) functional unit for digital signal pro- (FFT) is one of the mostly used transformations, which greatly cessors. MAC units with single-instruction-multiple-data (SIMD) pushes the performance requirements. The data parallelism support are often used to increase the processing performance inherent in the FFT processing allows operating with many in modern signal processing processors. Compared to a real- independent MAC operations simultaneously. Therefore, a valued SIMD-MAC units, the proposed unit uses the same performance increment can be achieved by MAC units with multipliers to also support complex-valued SIMD-MAC and butterfly operations. The area overhead for the complex mode SIMD mechanisms, but many instructions are still needed to is small. Complex-valued operations speed up signal processing operate the real- and imaginary parts of complex numbers algorithms and make the execution more efficient in terms of separately. The use of single instructions in DSPs, executing power consumption. As a case study, a fast Fourier transform operations with complex numbers, can lead to a significant (FFT) is implemented for a VLIW-processor with a complex- performance gain in many signal processing algorithms. valued SIMD butterfly extension. The proposed functional unit is quantitatively evaluated in terms of performance, silicon area, A SIMD-MAC unit that can handle both complex and and power consumption. -
EECS 570 Lecture 5 GPU Winter 2021 Prof
EECS 570 Lecture 5 GPU Winter 2021 Prof. Satish Narayanasamy http://www.eecs.umich.edu/courses/eecs570/ Slides developed in part by Profs. Adve, Falsafi, Martin, Roth, Nowatzyk, and Wenisch of EPFL, CMU, UPenn, U-M, UIUC. 1 EECS 570 • Slides developed in part by Profs. Adve, Falsafi, Martin, Roth, Nowatzyk, and Wenisch of EPFL, CMU, UPenn, U-M, UIUC. Discussion this week • Term project • Form teams and start to work on identifying a problem you want to work on Readings For next Monday (Lecture 6): • Michael Scott. Shared-Memory Synchronization. Morgan & Claypool Synthesis Lectures on Computer Architecture (Ch. 1, 4.0-4.3.3, 5.0-5.2.5). • Alain Kagi, Doug Burger, and Jim Goodman. Efficient Synchronization: Let Them Eat QOLB, Proc. 24th International Symposium on Computer Architecture (ISCA 24), June, 1997. For next Wednesday (Lecture 7): • Michael Scott. Shared-Memory Synchronization. Morgan & Claypool Synthesis Lectures on Computer Architecture (Ch. 8-8.3). • M. Herlihy, Wait-Free Synchronization, ACM Trans. Program. Lang. Syst. 13(1): 124-149 (1991). Today’s GPU’s “SIMT” Model CIS 501 (Martin): Vectors 5 Graphics Processing Units (GPU) • Killer app for parallelism: graphics (3D games) Tesla S870 What is Behind such an Evolution? • The GPU is specialized for compute-intensive, highly data parallel computation (exactly what graphics rendering is about) ❒ So, more transistors can be devoted to data processing rather than data caching and flow control ALU ALU Control ALU ALU CPU GPU Cache DRAM DRAM • The fast-growing video game industry -
Computer Architecture: Dataflow (Part I)
Computer Architecture: Dataflow (Part I) Prof. Onur Mutlu Carnegie Mellon University A Note on This Lecture n These slides are from 18-742 Fall 2012, Parallel Computer Architecture, Lecture 22: Dataflow I n Video: n http://www.youtube.com/watch? v=D2uue7izU2c&list=PL5PHm2jkkXmh4cDkC3s1VBB7- njlgiG5d&index=19 2 Some Required Dataflow Readings n Dataflow at the ISA level q Dennis and Misunas, “A Preliminary Architecture for a Basic Data Flow Processor,” ISCA 1974. q Arvind and Nikhil, “Executing a Program on the MIT Tagged- Token Dataflow Architecture,” IEEE TC 1990. n Restricted Dataflow q Patt et al., “HPS, a new microarchitecture: rationale and introduction,” MICRO 1985. q Patt et al., “Critical issues regarding HPS, a high performance microarchitecture,” MICRO 1985. 3 Other Related Recommended Readings n Dataflow n Gurd et al., “The Manchester prototype dataflow computer,” CACM 1985. n Lee and Hurson, “Dataflow Architectures and Multithreading,” IEEE Computer 1994. n Restricted Dataflow q Sankaralingam et al., “Exploiting ILP, TLP and DLP with the Polymorphous TRIPS Architecture,” ISCA 2003. q Burger et al., “Scaling to the End of Silicon with EDGE Architectures,” IEEE Computer 2004. 4 Today n Start Dataflow 5 Data Flow Readings: Data Flow (I) n Dennis and Misunas, “A Preliminary Architecture for a Basic Data Flow Processor,” ISCA 1974. n Treleaven et al., “Data-Driven and Demand-Driven Computer Architecture,” ACM Computing Surveys 1982. n Veen, “Dataflow Machine Architecture,” ACM Computing Surveys 1986. n Gurd et al., “The Manchester prototype dataflow computer,” CACM 1985. n Arvind and Nikhil, “Executing a Program on the MIT Tagged-Token Dataflow Architecture,” IEEE TC 1990. -
A Dataflow Architecture for Beamforming Operations
A dataflow architecture for beamforming operations Msc Assignment by Rinse Wester Supervisors: dr. ir. Andr´eB.J. Kokkeler dr. ir. Jan Kuper ir. Kenneth Rovers Anja Niedermeier, M.Sc ir. Andr´eW. Gunst dr. Albert-Jan Boonstra Computer Architecture for Embedded Systems Faculty of EEMCS University of Twente December 10, 2010 Abstract As current radio telescopes get bigger and bigger, so does the demand for processing power. General purpose processors are considered infeasible for this type of processing which is why this thesis investigates the design of a dataflow architecture. This architecture is able to execute the operations which are common in radio astronomy. The architecture presented in this thesis, the FlexCore, exploits regularities found in the mathematics on which the radio telescopes are based: FIR filters, FFTs and complex multiplications. Analysis shows that there is an overlap in these operations. The overlap is used to design the ALU of the architecture. However, this necessitates a way to handle state of the FIR filters. The architecture is not only able to execute dataflow graphs but also uses the dataflow techniques in the implementation. All communication between modules of the architecture are based on dataflow techniques i.e. execution is triggered by the availability of data. This techniques has been implemented using the hardware description language VHDL and forms the basis for the FlexCore design. The FlexCore is implemented using the TSMC 90 nm tech- nology. The design is done in two phases, first a design with a standard ALU is given which acts as reference design, secondly the Extended FlexCore is presented. -
14 Superscalar Processors
UNIT- 5 Chapter 14 Instruction Level Parallelism and Superscalar Processors What is Superscalar? • Use multiple independent instruction pipeline. • Instruction level parallelism • Identify dependencies in program • Eliminate Unnecessary dependencies • Use additional registers & renaming of register references in original code. • Branch prediction improves efficiency What is Superscalar? • RISC-like instructions, one per word • Multiple parallel execution units • Reorders and optimizes instruction stream at run time • Branch prediction with speculative execution of one path • Loads data from memory only when needed, and tries to find the data in the caches first Why Superscalar? • In 1987, scalar instruction • Most operations are on scalar quantities • Improving these operations to get an overall improvement • High performance microprocessors. General Superscalar Organization Superscalar V/S Superpipelined • Ordinary:- • One instruction/clock cycle & can perform one pipeline stage per clock cycle. • Superpipelined:- • 2 pipeline stage per cycle • Execution time:-half a clock cycle • Double internal clock speed gets two tasks per external clock cycle • Superscalar :- • allows parallel fetch execute • Start of the program & at branch target it performs better than above said. Superscalar v Superpipeline Limitations • Instruction level parallelism • Compiler based optimisation • Hardware techniques • Limited by —True data dependency —Procedural dependency —Resource conflicts —Output dependency —Antidependency True Data Dependency • ADD r1, -
Concepts Introduced in Chapter 3 Instruction Level Parallelism (ILP)
Intro Compiler Techs Branch Pred Dynamic Sched Speculation Multi Issue ILP Limits MT Intro Compiler Techs Branch Pred Dynamic Sched Speculation Multi Issue ILP Limits MT Concepts Introduced in Chapter 3 Instruction Level Parallelism (ILP) introduction Pipelining is the overlapping of dierent portions of instruction compiler techniques for ILP execution. advanced branch prediction Instruction level parallelism is the parallel execution of a dynamic scheduling sequence of instructions associated with a single thread of speculation execution. multiple issue scheduling approaches to exploit ILP static (compiler) limits of ILP dynamic (hardware) multithreading Intro Compiler Techs Branch Pred Dynamic Sched Speculation Multi Issue ILP Limits MT Intro Compiler Techs Branch Pred Dynamic Sched Speculation Multi Issue ILP Limits MT Data Dependences Control Dependences An instruction is control dependent on a branch instruction if the instruction will only be executed when the branch has a specic result. An instruction that is control dependent on a branch cannot be moved before the branch so that its execution is not controlled by the branch. Instructions must be independent to be executed in parallel. instruction types of data dependences branch branch True dependences can lead to RAW hazards. name dependences instruction Antidependences can lead to WAR hazards. before transformation after transformation Output dependences can lead to WAW hazards. An instruction that is not control dependent on a branch cannot be moved after the branch so that its execution is controlled by the branch. instruction branch branch instruction before transformation after transformation Intro Compiler Techs Branch Pred Dynamic Sched Speculation Multi Issue ILP Limits MT Intro Compiler Techs Branch Pred Dynamic Sched Speculation Multi Issue ILP Limits MT Static Scheduling Latencies of FP Operations Used in This Chapter The latency here indicates the number of intervening independent instructions that are needed to avoid a stall. -
Arxiv:1801.05178V1 [Cs.AR] 16 Jan 2018 Single-Instruction Multiple Threads (SIMT) Model
Inter-thread Communication in Multithreaded, Reconfigurable Coarse-grain Arrays Dani Voitsechov1 and Yoav Etsion1;2 Electrical Engineering1 Computer Science2 Technion - Israel Institute of Technology {dani,yetsion}@tce.technion.ac.il ABSTRACT the order of scheduling of the threads within a CTA is un- Traditional von Neumann GPGPUs only allow threads to known, a synchronization barrier must be invoked before communicate through memory on a group-to-group basis. consumer threads can read the values written to the shared In this model, a group of producer threads writes interme- memory by their respective producer threads. diate values to memory, which are read by a group of con- Seeking an alternative to the von Neumann GPGPU model, sumer threads after a barrier synchronization. To alleviate both the research community and industry began exploring the memory bandwidth imposed by this method of commu- dataflow-based systolic and coarse-grained reconfigurable ar- nication, GPGPUs provide a small scratchpad memory that chitectures (CGRA) [1–5]. As part of this push, Voitsechov prevents intermediate values from overloading DRAM band- and Etsion introduced the massively multithreaded CGRA width. (MT-CGRA) architecture [6,7], which maps the compute In this paper we introduce direct inter-thread communica- graph of CUDA kernels to a CGRA and uses the dynamic tions for massively multithreaded CGRAs, where intermedi- dataflow execution model to run multiple CUDA threads. ate values are communicated directly through the compute The MT-CGRA architecture leverages the direct connectiv- fabric on a point-to-point basis. This method avoids the ity between functional units, provided by the CGRA fab- need to write values to memory, eliminates the need for a ric, to eliminate multiple von Neumann bottlenecks includ- dedicated scratchpad, and avoids workgroup-global barriers. -
A Many-Core Architecture for In-Memory Data Processing
A Many-core Architecture for In-Memory Data Processing Sandeep R Agrawal Sam Idicula Arun Raghavan [email protected] [email protected] [email protected] Oracle Labs Oracle Labs Oracle Labs Evangelos Vlachos Venkatraman Govindaraju Venkatanathan Varadarajan [email protected] [email protected] venkatanathan.varadarajan@oracle. Oracle Labs Oracle Labs com Oracle Labs Cagri Balkesen Georgios Giannikis Charlie Roth [email protected] [email protected] [email protected] Oracle Labs Oracle Labs Oracle Labs Nipun Agarwal Eric Sedlar [email protected] [email protected] Oracle Labs Oracle Labs ABSTRACT ACM Reference format: For many years, the highest energy cost in processing has been Sandeep R Agrawal, Sam Idicula, Arun Raghavan, Evangelos Vlachos, Venka- traman Govindaraju, Venkatanathan Varadarajan, Cagri Balkesen, Georgios data movement rather than computation, and energy is the limiting Giannikis, Charlie Roth, Nipun Agarwal, and Eric Sedlar. 2017. A Many-core factor in processor design [21]. As the data needed for a single Architecture for In-Memory Data Processing. In Proceedings of MICRO-50, application grows to exabytes [56], there is clearly an opportunity Cambridge, MA, USA, October 14–18, 2017, 14 pages. to design a bandwidth-optimized architecture for big data compu- https://doi.org/10.1145/3123939.3123985 tation by specializing hardware for data movement. We present the Data Processing Unit or DPU, a shared memory many-core that is specifically designed for high bandwidth analytics workloads. 1 INTRODUCTION The DPU contains a unique Data Movement System (DMS), which A large number of data analytics applications in areas varying provides hardware acceleration for data movement and partition- from business intelligence, health sciences and real time log and ing operations at the memory controller that is sufficient to keep telemetry analysis already benefit from working sets that span up with DDR bandwidth. -
Intro Evolution of Superscalar Processor
Superscalar Processors Superscalar Processors vs. VLIW • 7.1 Introduction • 7.2 Parallel decoding • 7.3 Superscalar instruction issue • 7.4 Shelving • 7.5 Register renaming • 7.6 Parallel execution • 7.7 Preserving the sequential consistency of instruction execution • 7.8 Preserving the sequential consistency of exception processing • 7.9 Implementation of superscalar CISC processors using a superscalar RISC core • 7.10 Case studies of superscalar processors TECH Computer Science CH01 Superscalar Processor: Intro Emergence and spread of superscalar processors • Parallel Issue • Parallel Execution • {Hardware} Dynamic Instruction Scheduling • Currently the predominant class of processors 4Pentium 4PowerPC 4UltraSparc 4AMD K5- 4HP PA7100- 4DEC α Evolution of superscalar processor Specific tasks of superscalar processing Parallel decoding {and Dependencies check} Decoding and Pre-decoding • What need to be done • Superscalar processors tend to use 2 and sometimes even 3 or more pipeline cycles for decoding and issuing instructions • >> Pre-decoding: 4shifts a part of the decode task up into loading phase 4resulting of pre-decoding f the instruction class f the type of resources required for the execution f in some processor (e.g. UltraSparc), branch target addresses calculation as well 4the results are stored by attaching 4-7 bits • + shortens the overall cycle time or reduces the number of cycles needed The principle of perdecoding Number of perdecode bits used Specific tasks of superscalar processing: Issue 7.3 Superscalar instruction issue • How and when to send the instruction(s) to EU(s) Instruction issue policies of superscalar processors: Issue policies ---Performance, tread-----Æ Issue rate {How many instructions/cycle} Issue policies: Handing Issue Blockages • CISC about 2 • RISC: Issue stopped by True dependency Issue order of instructions • True dependency Æ (Blocked: need to wait) Aligned vs. -
NVIDIA Bluefield-2 Datasheet
NVIDIA BLUEFIELD-2 DPU DATA CENTER INFRASTRUCTURE ON A CHIP The NVIDIA® BlueField®-2 data processing unit (DPU) is the world’s first data center Key Features infrastructure-on-a-chip optimized for traditional enterprises’ modern cloud workloads and high performance computing. It delivers a broad set of accelerated software- Security defined networking, storage, security, and management services with the ability to > Hardened isolation layer offload, accelerate and isolate data center infrastructure. With its 200Gb/s Ethernet or > Hardware root of trust > IPsec/TLS and AES-XTS encryption InfiniBand connectivity, the BlueField-2 DPU enables organizations to transform their IT acceleration infrastructures into state-of-the-art data centers that are accelerated, fully > Connection tracking for stateful firewall and programmable, and armed with “zero trust” security to prevent data breaches and IDS/IPS cyber attacks. > Regular expression (RegEx) matching processor ® By combining the industry-leading NVIDIA ConnectX -6 Dx network adapter with an Storage ® array of Arm cores and infrastructure-specific offloads, BlueField-2 offers purpose- > NVIDIA GPUDirect® Storage built, hardware-acceleration engines with full software programmability. Sitting at the > Elastic block storage enabled by BlueField edge of every server, BlueField-2 empowers agile, secured and high-performance cloud SNAP storage virtualization > Compression and decompression and artificial intelligence (AI) workloads, all while reducing the total cost of ownership acceleration and increasing data center efficiency. > NVMe-oF acceleration > VirtIO-blk acceleration The NVIDIA DOCA™ software framework enables developers to rapidly create applications and services for the BlueField-2 DPU. NVIDIA DOCA makes it easy to Networking leverage DPU hardware accelerators, providing breakthrough data center performance, > RoCE, Zero Touch RoCE efficiency and security. -
Simty: Generalized SIMT Execution on RISC-V Caroline Collange
Simty: generalized SIMT execution on RISC-V Caroline Collange To cite this version: Caroline Collange. Simty: generalized SIMT execution on RISC-V. CARRV 2017: First Work- shop on Computer Architecture Research with RISC-V, Oct 2017, Boston, United States. pp.6, 10.1145/nnnnnnn.nnnnnnn. hal-01622208 HAL Id: hal-01622208 https://hal.inria.fr/hal-01622208 Submitted on 7 Oct 2020 HAL is a multi-disciplinary open access L’archive ouverte pluridisciplinaire HAL, est archive for the deposit and dissemination of sci- destinée au dépôt et à la diffusion de documents entific research documents, whether they are pub- scientifiques de niveau recherche, publiés ou non, lished or not. The documents may come from émanant des établissements d’enseignement et de teaching and research institutions in France or recherche français ou étrangers, des laboratoires abroad, or from public or private research centers. publics ou privés. Simty: generalized SIMT execution on RISC-V Caroline Collange Inria [email protected] ABSTRACT and programming languages to target GPU-like SIMT cores. Be- We present Simty, a massively multi-threaded RISC-V processor side simplifying software layers, the unification of CPU and GPU core that acts as a proof of concept for dynamic inter-thread vector- instruction sets eases prototyping and debugging of parallel pro- ization at the micro-architecture level. Simty runs groups of scalar grams. We have implemented Simty in synthesizable VHDL and threads executing SPMD code in lockstep, and assembles SIMD synthesized it for an FPGA target. instructions dynamically across threads. Unlike existing SIMD or We present our approach to generalizing the SIMT model in SIMT processors like GPUs or vector processors, Simty vector- Section 2, then describe Simty’s microarchitecture is Section 3, and izes scalar general-purpose binaries.