The document summarizes different types of pipeline hazards that can occur in a processor pipeline: structural hazards which occur due to limited hardware resources and prevent certain combinations of instructions from executing simultaneously; data hazards which occur when instructions depend on results of previous instructions in a way exposed by pipelining; and control hazards which occur due to pipelining of branches whose target may not be known until later in the pipeline. It describes techniques for handling these hazards such as forwarding, stalling, and instruction scheduling to minimize performance impacts.
Pipelining is a technique where the instruction execution process is divided into multiple stages that can operate in parallel. This allows subsequent instructions to begin processing before previous ones have finished. For example, with laundry, pipelining allows washing, drying, and folding different loads simultaneously to complete all the laundry faster. In processors, pipelining overlaps the stages of instruction fetch, decode, execute, and writeback to improve throughput. While pipelining improves performance, it can introduce hazards like structural, data, and control hazards that must be addressed.
1) Arithmetic pipelines divide arithmetic operations like multiplication and floating point addition into multiple stages to perform the operations concurrently and increase computational speed.
2) Vector and array processors use multiple processing elements that can perform the same operation on multiple data items simultaneously, further increasing speed.
3) Pipelining helps throughput by allowing new tasks to begin before previous ones finish, but does not reduce the latency of individual tasks. The pipeline rate is limited by its slowest stage.
Faster microprocessor design presentation in American International University-Bangladesh (AIUB). Presentation was taken under the subject "SELECTED TOPICS IN ELECTRICAL AND ELECTRONIC ENGINEERING (PROCESSOR AND DSP HARDWARE DESIGN WITH SYSTEM VERILOG, VHDL AND FPGAS) [MEEE]", as a final semester student of M.Sc at AIUB.
This document discusses deadlocks in operating systems. It defines a deadlock as when a set of processes are blocked because each process is holding a resource and waiting for another resource held by another process. Four conditions must be met simultaneously for a deadlock to occur: mutual exclusion, hold and wait, no preemption, and circular wait. An example of a deadlock between two processes, Process 1 and Process 2, is provided. Methods for handling deadlocks include prevention/avoidance, detection and recovery, and ignoring the problem. Prevention negates one of the necessary conditions, while avoidance uses strategies like Banker's algorithm to ensure deadlocks are avoided.
Defined instruction set architecture, discussed different types of instructions in the MIPS architecture, e.g., arithmetic, logical, shift etc. Discussed different types of registers in MIPS, R-format, I-format and j-format instructions have been explained with examples. Further assembly language code for conditional operations e.g., if..else, swap operation, loop operation are demonstrated.
Pipelining is a technique where the instruction execution process is divided into multiple stages that can operate in parallel. This allows subsequent instructions to begin processing before previous ones have finished. For example, with laundry, pipelining allows washing, drying, and folding different loads simultaneously to complete all the laundry faster. In processors, pipelining overlaps the stages of instruction fetch, decode, execute, and writeback to improve throughput. While pipelining improves performance, it can introduce hazards like structural, data, and control hazards that must be addressed.
1) Arithmetic pipelines divide arithmetic operations like multiplication and floating point addition into multiple stages to perform the operations concurrently and increase computational speed.
2) Vector and array processors use multiple processing elements that can perform the same operation on multiple data items simultaneously, further increasing speed.
3) Pipelining helps throughput by allowing new tasks to begin before previous ones finish, but does not reduce the latency of individual tasks. The pipeline rate is limited by its slowest stage.
Faster microprocessor design presentation in American International University-Bangladesh (AIUB). Presentation was taken under the subject "SELECTED TOPICS IN ELECTRICAL AND ELECTRONIC ENGINEERING (PROCESSOR AND DSP HARDWARE DESIGN WITH SYSTEM VERILOG, VHDL AND FPGAS) [MEEE]", as a final semester student of M.Sc at AIUB.
This document discusses deadlocks in operating systems. It defines a deadlock as when a set of processes are blocked because each process is holding a resource and waiting for another resource held by another process. Four conditions must be met simultaneously for a deadlock to occur: mutual exclusion, hold and wait, no preemption, and circular wait. An example of a deadlock between two processes, Process 1 and Process 2, is provided. Methods for handling deadlocks include prevention/avoidance, detection and recovery, and ignoring the problem. Prevention negates one of the necessary conditions, while avoidance uses strategies like Banker's algorithm to ensure deadlocks are avoided.
Defined instruction set architecture, discussed different types of instructions in the MIPS architecture, e.g., arithmetic, logical, shift etc. Discussed different types of registers in MIPS, R-format, I-format and j-format instructions have been explained with examples. Further assembly language code for conditional operations e.g., if..else, swap operation, loop operation are demonstrated.
The document discusses pipelining in computer processors. It describes how pipelining can increase throughput by overlapping the execution of multiple instructions. It discusses the basic pipeline stages for a RISC instruction set, including fetch, decode, execute, memory access, and writeback. It also describes several types of pipeline hazards that can occur, such as structural hazards caused by resource conflicts, data hazards when instructions depend on previous results, and control hazards with branches. Forwarding techniques are presented to help address data hazards.
This document discusses pipelining in microprocessors. It describes how pipelining works by dividing instruction processing into stages - fetch, decode, execute, memory, and write back. This allows subsequent instructions to begin processing before previous instructions have finished, improving processor efficiency. The document provides estimated timing for each stage and notes advantages like quicker execution for large programs, while disadvantages include added hardware and potential pipeline hazards disrupting smooth execution. It then gives examples of how four instructions would progress through each stage in a pipelined versus linear fashion.
Data manipulation instructions perform operations on data and provide computational capabilities for computers. These instructions are divided into three basic types: arithmetic instructions, logical and bit manipulation instructions, and shift instructions. Arithmetic instructions include addition, subtraction, multiplication, division, and incrementing and decrementing values. Logical and bit manipulation instructions operate on individual bits and include AND, OR, XOR, and clearing, complementing, and manipulating carry bits. Shift instructions shift the contents of an operand left or right in logical, arithmetic, or rotate operations.
RAR (Read After Read) is not considered a data hazard because it does not change the order of memory accesses or introduce incorrect results. Multiple instructions can safely read the same register without interfering with each other. The three types of data hazards that can occur are RAW (Read After Write), WAR (Write After Read), and WAW (Write After Write) which all involve write operations that could potentially overwrite data before it is read.
Pipelining is an speed up technique where multiple instructions are overlapped in execution on a processor. It is an important topic in Computer Architecture.
This slide try to relate the problem with real life scenario for easily understanding the concept and show the major inner mechanism.
The document discusses MIPS architecture memory organization and registers. It explains that memory is used to store data and instructions, and is divided into text, data, and stack segments. It also describes the MIPS register set, which includes 32 general purpose registers used for arithmetic operations as well as special purpose registers like $ra for return addresses. Basic MIPS instructions like load, store, arithmetic, and jumps are explained along with addressing modes like immediate, register, and memory addressing.
Pipeline Hazards can be classified into three types: structural hazards caused by hardware resource conflicts, data hazards caused when an instruction depends on the results of a previous instruction, and control hazards from conditional branches. Structural hazards arise from limited hardware resources like register files and memory ports. Data hazards include RAW, WAW, and WAR and are resolved by stalling or forwarding. Forwarding minimizes stalls by directly connecting new values to the next stage.
The document discusses binary search trees and their operations. It defines key concepts like nodes, leaves, root, and tree traversal methods. It then explains how to search, insert, find minimum/maximum elements, and traverse a binary search tree. Searching a BST involves recursively comparing the target key to node keys and traversing left or right. Insertion finds the appropriate position by moving pointers down the tree until reaching an empty node.
This document discusses deadlock avoidance techniques. It explains the concepts of safe and unsafe states when allocating resources to processes. The resource allocation graph algorithm uses claim and assignment edges to model potential resource requests. Banker's algorithm requires processes to declare maximum resource needs upfront. It uses an allocation matrix and need matrix to determine if allocating resources to a process will result in an unsafe state. An example demonstrates tracking available resources and determining if processes can safely obtain requested resources without causing deadlock.
A demand-paging system is similar to a paging system, discussed earlier, with a little difference that it uses - swapping.
Processes reside on secondary memory (which is usually a disk).
When we want to execute a process, we swap it into memory.
Rather than swapping the entire process into memory, however, we use a lazy swapper, which swaps a page into memory only when that page is needed.
Since we are now viewing a process as a sequence of pages, rather than one large contiguous address space, the use of the term swap will not technically correct.
A swapper manipulates entire processes, whereas a pager is concerned with the individual pages of a process.
We shall thus use the term pager, rather than swapper, in connection with demand paging.
This document outlines a presentation on pipelining and data hazards in microprocessors. It begins with rules for participant questions and outlines the topics to be covered: what is pipelining, types of pipelining, data hazards and their types, and solutions to data hazards. It then defines pipelining as executing subsequent instructions before prior ones complete. Types of pipelining include control, data, and structure hazards. Data hazards occur if an instruction uses a value before it is ready, and their types are RAW, WAR, and WAW. Solutions involve forwarding newer register values to bypass stale values in the pipeline and prevent hazards.
basic computer programming and micro programmed controlRai University
The document discusses microprogrammed control unit implementation. It describes that a microprogrammed control unit uses microinstructions stored in read-only control memory to generate control signals for executing microoperations. Each computer instruction is mapped to a routine in control memory containing a sequence of microinstructions. The microinstructions include fields that specify microoperations to perform and the address of the next microinstruction. A control address register holds the address of the current microinstruction, and a next address generator determines the next address based on branching conditions.
The document provides details about the basic processing unit of a processor. It discusses the internal functional units of a processor and how they are connected via a single common bus. The key components include the ALU, registers, program counter, instruction register, and memory data register. It describes how a processor fetches and executes instructions in a sequence of steps by transferring data between registers and performing operations. The document also covers different approaches to generating the internal control signals like hardwired control and microprogrammed control using microinstructions.
The document discusses instruction execution in a computer processor. It describes how a processor executes instructions by fetching them from memory using the program counter. The instruction is placed in the instruction register and decoded by the control unit. The control unit then selects components like the ALU to carry out operations. Common components involved in instruction execution are the program counter, memory address register, instruction register, memory buffer register, control unit, arithmetic logic unit, and accumulator. The execution cycle involves fetching the instruction from memory address, decoding it, and then executing the instruction.
RISC - Reduced Instruction Set ComputingTushar Swami
This document discusses RISC (Reduced Instruction Set Computer) architecture. It includes a member list, outline of topics to be covered, and acknowledgements. The main topics covered are what RISC is, the background and history of RISC, characteristics of RISC like simplified instructions and pipelining, differences between RISC and CISC, performance equations, and applications of RISC like in mobile systems, high-end computing, and ARM and MIPS architectures. It concludes that over time, the differences between RISC and CISC have blurred as they have adopted each other's strategies.
This document discusses superscalar and super pipeline approaches to improving processor performance. Superscalar processors execute multiple independent instructions in parallel using multiple pipelines. Super pipelines break pipeline stages into smaller stages to reduce clock period and increase instruction throughput. While superscalar utilizes multiple parallel pipelines, super pipelines perform multiple stages per clock cycle in each pipeline. Super pipelines benefit from higher parallelism but also increase potential stalls from dependencies. Both approaches aim to maximize parallel instruction execution but face limitations from true data and other dependencies.
(Ref : Computer System Architecture by Morris Mano 3rd edition) : Microprogrammed Control unit, micro instructions, micro operations, symbolic and binary microprogram.
The document discusses the concept of virtual memory. Virtual memory allows a program to access more memory than what is physically available in RAM by storing unused portions of the program on disk. When a program requests data that is not currently in RAM, it triggers a page fault that causes the needed page to be swapped from disk into RAM. This allows the illusion of more memory than physically available through swapping pages between RAM and disk as needed by the program during execution.
The document provides an overview of parallel processing and multiprocessor systems. It discusses Flynn's taxonomy, which classifies computers as SISD, SIMD, MISD, or MIMD based on whether they process single or multiple instructions and data in parallel. The goals of parallel processing are to reduce wall-clock time and solve larger problems. Multiprocessor topologies include uniform memory access (UMA) and non-uniform memory access (NUMA) architectures.
There are situations, called hazards, that prevent the next instruction in the instruction stream from executing during its designated cycle
There are three classes of hazards
Structural hazard
Data hazard
Branch hazard
pipelining is the concept of decomposing the sequential process into number of small stages in which each stage execute individual parts of instruction life cycle inside the processor.
The document discusses pipelining in computer processors. It describes how pipelining can increase throughput by overlapping the execution of multiple instructions. It discusses the basic pipeline stages for a RISC instruction set, including fetch, decode, execute, memory access, and writeback. It also describes several types of pipeline hazards that can occur, such as structural hazards caused by resource conflicts, data hazards when instructions depend on previous results, and control hazards with branches. Forwarding techniques are presented to help address data hazards.
This document discusses pipelining in microprocessors. It describes how pipelining works by dividing instruction processing into stages - fetch, decode, execute, memory, and write back. This allows subsequent instructions to begin processing before previous instructions have finished, improving processor efficiency. The document provides estimated timing for each stage and notes advantages like quicker execution for large programs, while disadvantages include added hardware and potential pipeline hazards disrupting smooth execution. It then gives examples of how four instructions would progress through each stage in a pipelined versus linear fashion.
Data manipulation instructions perform operations on data and provide computational capabilities for computers. These instructions are divided into three basic types: arithmetic instructions, logical and bit manipulation instructions, and shift instructions. Arithmetic instructions include addition, subtraction, multiplication, division, and incrementing and decrementing values. Logical and bit manipulation instructions operate on individual bits and include AND, OR, XOR, and clearing, complementing, and manipulating carry bits. Shift instructions shift the contents of an operand left or right in logical, arithmetic, or rotate operations.
RAR (Read After Read) is not considered a data hazard because it does not change the order of memory accesses or introduce incorrect results. Multiple instructions can safely read the same register without interfering with each other. The three types of data hazards that can occur are RAW (Read After Write), WAR (Write After Read), and WAW (Write After Write) which all involve write operations that could potentially overwrite data before it is read.
Pipelining is an speed up technique where multiple instructions are overlapped in execution on a processor. It is an important topic in Computer Architecture.
This slide try to relate the problem with real life scenario for easily understanding the concept and show the major inner mechanism.
The document discusses MIPS architecture memory organization and registers. It explains that memory is used to store data and instructions, and is divided into text, data, and stack segments. It also describes the MIPS register set, which includes 32 general purpose registers used for arithmetic operations as well as special purpose registers like $ra for return addresses. Basic MIPS instructions like load, store, arithmetic, and jumps are explained along with addressing modes like immediate, register, and memory addressing.
Pipeline Hazards can be classified into three types: structural hazards caused by hardware resource conflicts, data hazards caused when an instruction depends on the results of a previous instruction, and control hazards from conditional branches. Structural hazards arise from limited hardware resources like register files and memory ports. Data hazards include RAW, WAW, and WAR and are resolved by stalling or forwarding. Forwarding minimizes stalls by directly connecting new values to the next stage.
The document discusses binary search trees and their operations. It defines key concepts like nodes, leaves, root, and tree traversal methods. It then explains how to search, insert, find minimum/maximum elements, and traverse a binary search tree. Searching a BST involves recursively comparing the target key to node keys and traversing left or right. Insertion finds the appropriate position by moving pointers down the tree until reaching an empty node.
This document discusses deadlock avoidance techniques. It explains the concepts of safe and unsafe states when allocating resources to processes. The resource allocation graph algorithm uses claim and assignment edges to model potential resource requests. Banker's algorithm requires processes to declare maximum resource needs upfront. It uses an allocation matrix and need matrix to determine if allocating resources to a process will result in an unsafe state. An example demonstrates tracking available resources and determining if processes can safely obtain requested resources without causing deadlock.
A demand-paging system is similar to a paging system, discussed earlier, with a little difference that it uses - swapping.
Processes reside on secondary memory (which is usually a disk).
When we want to execute a process, we swap it into memory.
Rather than swapping the entire process into memory, however, we use a lazy swapper, which swaps a page into memory only when that page is needed.
Since we are now viewing a process as a sequence of pages, rather than one large contiguous address space, the use of the term swap will not technically correct.
A swapper manipulates entire processes, whereas a pager is concerned with the individual pages of a process.
We shall thus use the term pager, rather than swapper, in connection with demand paging.
This document outlines a presentation on pipelining and data hazards in microprocessors. It begins with rules for participant questions and outlines the topics to be covered: what is pipelining, types of pipelining, data hazards and their types, and solutions to data hazards. It then defines pipelining as executing subsequent instructions before prior ones complete. Types of pipelining include control, data, and structure hazards. Data hazards occur if an instruction uses a value before it is ready, and their types are RAW, WAR, and WAW. Solutions involve forwarding newer register values to bypass stale values in the pipeline and prevent hazards.
basic computer programming and micro programmed controlRai University
The document discusses microprogrammed control unit implementation. It describes that a microprogrammed control unit uses microinstructions stored in read-only control memory to generate control signals for executing microoperations. Each computer instruction is mapped to a routine in control memory containing a sequence of microinstructions. The microinstructions include fields that specify microoperations to perform and the address of the next microinstruction. A control address register holds the address of the current microinstruction, and a next address generator determines the next address based on branching conditions.
The document provides details about the basic processing unit of a processor. It discusses the internal functional units of a processor and how they are connected via a single common bus. The key components include the ALU, registers, program counter, instruction register, and memory data register. It describes how a processor fetches and executes instructions in a sequence of steps by transferring data between registers and performing operations. The document also covers different approaches to generating the internal control signals like hardwired control and microprogrammed control using microinstructions.
The document discusses instruction execution in a computer processor. It describes how a processor executes instructions by fetching them from memory using the program counter. The instruction is placed in the instruction register and decoded by the control unit. The control unit then selects components like the ALU to carry out operations. Common components involved in instruction execution are the program counter, memory address register, instruction register, memory buffer register, control unit, arithmetic logic unit, and accumulator. The execution cycle involves fetching the instruction from memory address, decoding it, and then executing the instruction.
RISC - Reduced Instruction Set ComputingTushar Swami
This document discusses RISC (Reduced Instruction Set Computer) architecture. It includes a member list, outline of topics to be covered, and acknowledgements. The main topics covered are what RISC is, the background and history of RISC, characteristics of RISC like simplified instructions and pipelining, differences between RISC and CISC, performance equations, and applications of RISC like in mobile systems, high-end computing, and ARM and MIPS architectures. It concludes that over time, the differences between RISC and CISC have blurred as they have adopted each other's strategies.
This document discusses superscalar and super pipeline approaches to improving processor performance. Superscalar processors execute multiple independent instructions in parallel using multiple pipelines. Super pipelines break pipeline stages into smaller stages to reduce clock period and increase instruction throughput. While superscalar utilizes multiple parallel pipelines, super pipelines perform multiple stages per clock cycle in each pipeline. Super pipelines benefit from higher parallelism but also increase potential stalls from dependencies. Both approaches aim to maximize parallel instruction execution but face limitations from true data and other dependencies.
(Ref : Computer System Architecture by Morris Mano 3rd edition) : Microprogrammed Control unit, micro instructions, micro operations, symbolic and binary microprogram.
The document discusses the concept of virtual memory. Virtual memory allows a program to access more memory than what is physically available in RAM by storing unused portions of the program on disk. When a program requests data that is not currently in RAM, it triggers a page fault that causes the needed page to be swapped from disk into RAM. This allows the illusion of more memory than physically available through swapping pages between RAM and disk as needed by the program during execution.
The document provides an overview of parallel processing and multiprocessor systems. It discusses Flynn's taxonomy, which classifies computers as SISD, SIMD, MISD, or MIMD based on whether they process single or multiple instructions and data in parallel. The goals of parallel processing are to reduce wall-clock time and solve larger problems. Multiprocessor topologies include uniform memory access (UMA) and non-uniform memory access (NUMA) architectures.
There are situations, called hazards, that prevent the next instruction in the instruction stream from executing during its designated cycle
There are three classes of hazards
Structural hazard
Data hazard
Branch hazard
pipelining is the concept of decomposing the sequential process into number of small stages in which each stage execute individual parts of instruction life cycle inside the processor.
This document discusses instruction pipelining in processors. It begins by describing how early computers executed instructions sequentially through five stages. This led to low throughput as hardware sat idle between stages. Pipelining allows overlapping execution by dividing processors into stages with buffers between. This keeps most hardware busy, resembling baking multiple loaves simultaneously. The document outlines a five-stage pipeline and discusses how instructions flow through stages every clock cycle, improving throughput versus an unpipelined design.
1) Pipelining is a technique used in CPU design to improve throughput by allowing subsequent instructions to begin execution before previous instructions have finished. This document uses an example of laundry to illustrate how pipelining reduces the time to complete multiple loads from 6 hours to 3.5 hours.
2) Advances like superscalar, multi-core, and many-core architectures have attempted to improve CPU performance by executing multiple instructions simultaneously. However, fundamental limits like Amdahl's Law mean speedups from parallelism are limited by the fraction of a workload that can be parallelized.
3) GPUs and Intel's Xeon Phi coprocessor employ even more parallelism through massively multith
The document provides instructions for accessing and using Material Safety Data Sheets (MSDS) at a hospital. MSDS contain safety information about chemical properties, health effects, and proper handling procedures. At the hospital, MSDS are available online through the intranet 24/7 for any chemicals used at the hospital or in the community. The intranet site allows users to search for a chemical and access the corresponding MSDS as a PDF file with safety information to print if needed.
The document describes the design of a MIPS processor datapath. It discusses the basic components needed for a processor including a register file, ALU, program counter, and data memory. It then shows how these components can be connected to implement the execution of MIPS instructions, including register transfers, arithmetic/logical operations, loads/stores, and branches. The datapath design is able to execute a subset of the MIPS instruction set in a single clock cycle.
This document provides an overview of implementing a processor that executes a subset of the MIPS instruction set. It describes the basic components needed, including an instruction memory to store and fetch instructions, registers to hold data, an ALU to perform arithmetic and logical operations, multiplexers to direct data flow, and a program counter to keep track of the next instruction address. The implementation is built up incrementally, first explaining how instructions are fetched and the program counter updated. It then describes adding components for R-type instructions like arithmetic and logical operations. Finally, it discusses adding units to support load/store memory instructions by sign-extending offsets and calculating effective addresses. The goal is to explain at a high level how the MIPS
The document discusses instruction pipelining in computers. It begins with an analogy of pipelining laundry tasks to increase throughput. It then explains the concept of dividing instruction execution into stages (fetch, decode, execute, write) and executing instructions in parallel by having different stages work on different instructions. This allows higher instruction throughput. However, hazards like data dependencies between instructions, branches, cache misses can cause the pipeline to stall, reducing performance. Various techniques are discussed to handle hazards and maximize the benefits of pipelining.
This chapter discusses pipelining in computer processors. Pipelining improves processor throughput by allowing multiple instructions to be processed simultaneously across different stages. It involves dividing instruction execution into discrete stages, such as fetch, decode, execute, and writeback. Pipelining can improve performance but also introduces hazards such as data dependencies that require stalling the pipeline. Techniques like forwarding, reordering, and branch prediction help mitigate stalls and improve pipeline utilization.
This document summarizes key aspects of CPU processor design, including:
1) It examines two implementations of a MIPS processor - a simple single-cycle version and a more realistic pipelined version. The pipelined version breaks instruction execution into five stages to improve performance.
2) It discusses hazards that can occur in a pipeline like data hazards and branch hazards. Techniques like forwarding, stalling, and branch prediction are used to resolve hazards.
3) The control logic for the pipelined MIPS processor is explained, including how it detects hazards and forwards data between stages when needed. Stalls are also inserted when necessary to ensure correctness.
This chapter discusses processor structure and function. It covers the basic components of a CPU including registers, instruction cycles, and data flow. Key points include:
- A CPU must fetch, interpret, fetch operands for, process, and write data from instructions. It uses registers for temporary storage and a program counter to keep track of instructions.
- Common registers include general purpose, data, address, condition code, control/status, and program status registers. General purpose registers can vary in number, size, and whether they are general or specialized use.
- An instruction cycle involves fetching an instruction from memory, decoding it, fetching operands, executing the instruction, and writing results. Pipelining and branch prediction are
This document discusses instruction pipelining in computer processors. It begins by defining pipelining and explaining how it works like an assembly line to increase throughput. It then discusses different types of pipelines and introduces the MIPS instruction pipeline as an example. The document goes on to explain different types of pipeline hazards like structural hazards, control hazards, and data hazards. It provides examples of how to detect and resolve these hazards through techniques like forwarding, stalling, predicting, and delayed branching. Key concepts covered include pipeline registers, control signals, forwarding units, and branch prediction buffers.
The document discusses instruction pipelining in CPUs. It explains that instruction pipelining achieves greater CPU performance by overlapping the execution of multiple instructions. It describes the different stages in a basic two-stage pipeline as fetch and execute. It then discusses how further dividing the pipeline into more stages, such as six stages for fetch, decode, calculate, fetch operands, execute, and writeback, can provide even higher performance. However, it notes conditional branches can reduce efficiency since the next instruction is unknown until the branch is resolved. Various techniques to handle branches like branch prediction, prefetching the target, and delayed branches are described to improve pipeline performance.
This slide contain the description about the various technique related to parallel Processing(vector Processing and array processor), Arithmetic pipeline, Instruction Pipeline, SIMD processor, Attached array processor
The document discusses pipeline hazards including structural, data, and control hazards. It provides details on how each hazard can occur in a 5-stage pipeline and techniques to resolve them, including forwarding, stalling, and compiler scheduling. Data hazards are classified as RAW, WAW, and WAR. Control hazards from branches are reduced by computing the branch target and outcome earlier in the ID phase to minimize stalls.
This document summarizes the key components and organization of superscalar processor pipelines. It discusses how superscalar processors can execute multiple instructions per cycle by exploiting instruction-level parallelism. The document outlines the major stages in a superscalar pipeline including instruction fetch, decode, dispatch, execution, completion, and retirement. It also discusses limiting factors like structural hazards from resource conflicts, data hazards from dependencies between instructions, and control hazards from branches.
The document discusses pipeline hazards in computer architecture and their resolution mechanisms. There are three types of hazards: structural hazards which occur due to resource conflicts, data hazards which occur when an instruction depends on data from a prior instruction, and control hazards which occur due to conditional branch instructions. Data hazards include read after write (RAW), write after read (WAR), and write after write (WAW) hazards. Forwarding is a common technique to resolve data hazards by passing results directly from one pipeline stage to another as needed. Stalls can also resolve hazards by inserting no-operation instructions but reduce pipeline efficiency.
The document discusses pipeline hazards in computer architecture, including structural hazards that occur when multiple instructions attempt to use the same hardware resource, and data hazards that occur when an instruction tries to use data before it is ready. It provides examples of read after write, write after read, and write after write data hazards. Solutions to hazards include stalling the pipeline when hazards are detected or implementing forwarding to provide data to dependent instructions earlier than the register writeback stage.
The document summarizes instruction level parallelism and superscalar processors. It discusses how superscalar processors can fetch and execute multiple instructions simultaneously by taking advantage of independent instructions that do not have data dependencies. True data dependencies, procedural dependencies, resource conflicts, output dependencies, and antidependencies limit the degree of instruction level parallelism. The document then describes the design of superscalar processors including instruction issue policies, register renaming, and other techniques to enable out-of-order execution. It provides examples of superscalar processor implementations like the Pentium 4 and ARM Cortex-A8.
Instruction Level Parallelism and Superscalar ProcessorsSyed Zaid Irshad
Common instructions (arithmetic, load/store, conditional branch) can be initiated and executed independently
Equally applicable to RISC & CISC
In practice usually RISC
Advanced Pipelining in ARM Processors.pptxJoyChowdhury30
The document discusses advanced pipelining techniques in ARM processors. It begins with an overview of pipelining and its benefits of improving throughput by executing multiple instructions simultaneously. ARM processors implement different numbers of pipeline stages - 3 stages in ARM7, 5 stages in ARM9, 6 stages in ARM10, and 7 stages in ARM11. Issues like control hazards, data hazards, and interrupts are addressed through techniques like data forwarding, branch prediction, and out-of-order execution. The 6-stage pipeline in ARM10 achieves double the throughput of ARM7 while compromising on latency. Branch target buffers are used to reduce delays from branch instructions. The 7-stage pipeline in ARM11 and above further improves performance using advanced data
Processor Organization and ArchitectureDhaval Bagal
This document discusses processor organization and architecture. It covers the stored program concept where both instructions and data are stored in memory. It describes the Von Neumann architecture, which includes a main memory, ALU, control unit, and I/O. It discusses the registers used in processor control and execution like the program counter, accumulator, and instruction register. Finally, it examines addressing modes like immediate, direct, indirect, register, displacement, and stack addressing.
Pipelining is a technique used in microprocessors to overlap the execution of multiple instructions by dividing instruction execution into discrete stages. It allows the next instruction to begin executing before the previous one has finished. The pipeline is divided into segments that perform discrete operations concurrently. This improves processor throughput by allowing new instructions to enter the pipeline every clock cycle.
CPU Pipelining and Hazards - An IntroductionDilum Bandara
Pipelining is a technique used in computer architecture to overlap the execution of instructions to increase throughput. It works by breaking down instruction execution into a series of steps and allowing subsequent instructions to begin execution before previous ones complete. This allows multiple instructions to be in various stages of completion simultaneously. Pipelining improves performance but introduces hazards such as structural, data, and control hazards that can reduce the ideal speedup if not addressed properly. Control hazards due to branches are particularly challenging to handle efficiently.
The document discusses instruction scheduling on the ARM9TDMI processor. It describes the ARM9TDMI pipeline and how the timing of instructions depends on dependencies between stages. Two methods for scheduling load instructions are presented: preloading, where data for the next loop iteration is loaded at the end of the current loop, and unrolling the loop to interleave operations from different iterations. Unrolling achieves the best performance of 7 cycles per character compared to 11 cycles without scheduling.
This document discusses general-purpose processors. It begins by introducing general-purpose processors and their basic architecture, which consists of a control unit and datapath that is designed to perform a variety of computation tasks. It then describes the operations of loading, storing, and arithmetic/logical operations that can be performed by the datapath. Subsequent sections provide more details on the control unit and how it sequences operations, instruction cycles, architectural considerations like bit-width and clock frequency, and techniques for improving performance like pipelining and superscalar execution. The document concludes with sections on assembly-level instructions and programmer considerations.
The document discusses parallel processing and pipelining techniques in computer organization. It covers topics like parallel processing concepts and classifications, pipelining concepts and how it increases computational speed, arithmetic and instruction pipelining, handling pipeline hazards like data dependencies and branches. The key advantages of pipelining include decomposing tasks into sequential sub-operations that can complete concurrently, improving throughput and achieving speedup close to the number of pipeline stages when the number of tasks is large.
Pipelining of Processors Computer ArchitectureHaris456
Pipelining is a technique used in microprocessors to overlap the execution of multiple instructions to increase throughput. It works by dividing the instruction execution process into discrete stages, such as fetch, decode, execute, memory, and write-back. When an instruction enters one stage, the previous instruction can enter the next stage, allowing the processor to complete more than one instruction per clock cycle. Pipelining reduces the time needed to complete a series of instructions by allowing the stages to process separate instructions simultaneously rather than sequentially.
Interstage buffer B1 feeds the Decode stage with a newly-fetched instruction.
Interstage buffer B2 feeds the Compute stage with the two operands
Interstage buffer B3 holds the result of the ALU operation
Interstage buffer B4 feeds the Write stage with a value to be written into the register file
Similar to Ct213 processor design_pipelinehazard (20)
1. Content
• Introduction to pipeline hazard
• Structural Hazard
• Data Hazard
• Control Hazard
2. Pipeline Hazards (1)
• Pipeline Hazards are situations that prevent the next
instruction in the instruction stream from executing in its
designated clock cycle
• Hazards reduce the performance from the ideal speedup
gained by pipelining
• Three types of hazards
– Structural hazards
• Arise from resource conflicts when the hardware can’t support all possible
combinations of overlapping instructions
– Data hazards
• Arise when an instruction depends on the results of a previous instruction in
a way that is exposed by overlapping of instruction in pipeline
– Control hazards
• Arise from the pipelining of branches and other instructions that change the
PC (Program Counter)
3. Pipeline Hazards (2)
• Hazards in pipeline can make the pipeline to stall
• Eliminating a hazard often requires that some
instructions in the pipeline to be allowed to proceed
while others are delayed
– When an instruction is stalled, instructions issued latter
than the stalled instruction are stopped, while the ones
issued earlier must continue
• No new instructions are fetched during the stall
4. Structural Hazards (1)
• If certain combination of instructions can’t be
accommodated because of resource conflicts, the machine is
said to have a structural hazard
• It can be generated by:
– Some functional unit is not fully pipelined
– Some resources has not been duplicated enough to allow all the
combinations in the pipeline to execute
– For example: a machine may have only one register file write port,
but under certain conditions, the pipeline might want to perform
two writes in one clock cycle – this will generate structural hazard
• When a sequence of instructions encounter this hazard, the pipeline will
stall one of the instructions until the required unit is available
• Such stalls will increase the Clock cycle Per Instruction from its ideal 1 for
pipelined machines
5. Structural Hazards (2)
• Consider a Von Neumann architecture (same memory for instructions
and data)
7. Structural Hazards (4)
Instruction
Clock number
Number
1 2 3 4 5 6 7 8 9 10
load IF ID EX MEM WB
Instruction i+1 IF ID EX MEM WB
Instruction i+2 IF ID EX MEM WB
Instruction i+3 stall IF ID EX MEM WB
Instruction i+4 IF ID EX MEM WB
Instruction i+5 IF ID EX MEM
• Another way to represent the stall – no instruction is
initiated in clock cycle 4
8. Structural Hazards (5)
• A machine with structural hazard will have lower
CPI
• Why a designer allows structural hazard?
– To reduce cost
• Pipelining all the functional units or duplicating them may be
too costly
– To reduce latency
• Introducing too many pipeline stages may cause latency issues
9. Data Hazards (1)
• Data hazards occur when the pipeline changes the
order of read/write accesses to operands so that the
order differs from the order seen by sequentially
executing instructions on an un-pipelined machine
• Consider the execution of following instructions, on
our pipelined example processor:
– ADD R1, R2, R3
– SUB R4, R1, R5
– AND R6, R1, R7
– OR R8, R1, R9
– XOR R10, R1, R11
10. Data Hazards (2)
• The use of results from ADD instruction causes hazard since the
register is not written until after those instructions read it.
11. Data Hazards (3)
• Eliminate the stalls for the hazard involving SUB and AND
instructions using a technique called forwarding
12. Data Hazards (4)
• Store requires an operand during MEM and forwarding is shown here.
– The result of the load is forwarded from the output in MEM/WB to the memory
input to be stored
– In addition the ALUOutput is forwarded to ALU input for address calculation
for both Load and Store
13. Data Hazards Classification
• Depending on the order of read and write access in the
instructions, data hazards could be classified as three types.
• Consider two instructions i and j, with i occurring before j.
Possible data hazards:
– RAW (Read After Write)
• j tries to read a source before i writes to it , so j incorrectly gets the old
value;
• most common type of hazard, that is what we tried to explain so far.
– WAW (Write After Write)
• j tries to write an operand before is written by i. The write ends up being
performed in wrong order, having i overwrite the operand written by j, the
destination containing the operand written by i rather than the one written
by j
• Present in pipelines that write in more than one pipe stage
– WAR (Write After Read)
• j tries to write a destination before it is read by i, so the instruction i
incorrectly gets the new value
• This doesn’t happen in our example, since all reads are early and writes late
14. Data Hazards Requiring Stalls (1)
• Unfortunately not all data hazards can be handled by
forwarding. Consider the following sequence:
– LW R1, 0(R2)
– SUB R4, R1, R5
– AND R6, R1, R7
– OR R8, R1, R9
• The problem with this sequence is that the Load
operation will not have data until the end of MEM
stage.
15. Data Hazards Requiring Stalls (2)
• The load instruction can forward the results to AND and OR
instruction, but not to the SUB instruction since that would mean
forwarding results in “negative” time
16. Data Hazards Requiring Stalls (3)
• The load interlock causes a stall to be inserted at clock cycle 4,
delaying the SUB instruction and those that follow by one cycle.
– This delay allows the value to be successfully forwarded onto the next clock
cycle
17. Data Hazards Requiring Stalls (4)
LW R1, 0(R2) IF ID EX MEM WB
SUB R4, R1, R5 IF ID EX MEM WB
AND R6, R1, R7 IF ID EX MEM WB
OR R8, R1, R9 IF ID EX MEM WB
• Before stall insertion
LW R1, 0(R2) IF ID EX MEM WB
SUB R4, R1, R5 IF ID stall EX MEM WB
AND R6, R1, R7 IF stall ID EX MEM WB
OR R8, R1, R9 stall IF ID EX MEM WB
• After stall insertion
18. Compiler Scheduling for Data Hazards (1)
• Consider a typical code, such as A = B+C
LW R1, B IF ID EX MEM WB
LW R2, C IF ID EX MEM WB
ADD R3, R1, R2 IF ID stall EX MEM WB
SW A, R3 IF stall ID EX MEM WB
• The ADD instruction must be stalled to allow the load of C to complete
• The SW needs not be delayed because the forwarding hardware passes the result
from MEM/WB directly to the data memory input for storing
19. Compiler Scheduling for Data Hazards (2)
• Rather than just allow the pipeline to stall, the
compiler could try to schedule the pipeline to avoid
the stalls, by rearranging the code
– The compiler could try to avoid the generating the code
with a load followed by an immediate use of the load
destination register
– This technique is called pipeline scheduling or
instruction scheduling and it is a very used technique in
modern compilers
20. Instruction scheduling example
• Generate code for our example processor that avoids
pipeline stalls from the following sequence:
– A = B +C
– D=E-F
• Solution
– LW Rb, B
– LW Rc, C
– LW Re, E ; swap instructions to avoid stall
– ADD Ra, Rb, Rc
– LW Rf, f
– SW a, Ra ; swap instruction to avoid stall
– SUB Rd, Re, Rf
– SW d, Rd
21. Control Hazards (1)
• Can cause a greater performance loss than the data hazards
• When a branch is executed it may or it may not change the
PC (to other value than its value + 4)
– If a branch is changing the PC to its target address, than it is a
taken branch
– If a branch doesn’t change the PC to its target address, than it is a
not taken branch
• If instruction i is a taken branch, than the value of PC will
not change until the end MEM stage of the instruction
execution in the pipeline
– A simple method to deal with branches is to stall the pipe as soon
as we detect a branch until we know the result of the branch
22. Control Hazards (2)
Branch Instruction IF ID EX MEM WB
Branch Successor IF stall stall IF ID EX MEM WB
Branch Successor
+1 IF ID EX MEM WB
Branch Successor
+2 IF ID EX MEM
• A branch causes three cycle stall in our example processor
pipeline
– One cycle is a repeated IF – necessary if the branch would be
taken. If the branch is not taken, this IF is redundant
– Two idle cycles
23. Control Hazards (3)
• The three clock cycles lost for every branch is a
significant loss
– With a 30% branch frequency, the machine with branch
stalls achieves only about half of the speedup from
pipelining
– Reducing the branch penalty becomes critical
• The number of clock cycles in a branch stall can be
reduced by two steps:
– Find out if the branch is taken or not in early stage in the
pipeline
– Compute the taken PC (address of the branch target)
earlier
24. Control Hazards (4)
Reducing the stall from branch hazards by moving the zero test and branch calculation into ID
phase of pipeline. It uses a separate adder to compute the branch target address during ID.
Because the branch target addition happens during ID, it will happen for all instructions. The
branch condition (Regs[IF/ID.IR6…10] op 0) will also be done for all instructions. The selection
of the sequential PC or the branch target PC will still occur during IF, but now it uses values
from ID phase, rather than from EX/MEM register. In this case, the branch instruction is done by
the end of ID phase, so EX, MEM and WB stages are not used for branch instructions anymore.
25. Modified Pipelined Instruction Fetch
• Instruction Fetch
– IF/ID.IR mem[PC]
– IF/ID.NPC, PC if (Regs[IF/ID. IR6…10] op 0)
{IF/ID.NPC +(IF/ID.IR16)16##IF/ID.IR16…31}else{PC+4}
• Operation:
– send out the PC and fetch the instruction from memory
– Increment the PC by 4 to address the next instruction or
save the address generated by a taken branch of a
previous instruction in decode stage
26. Modified Pipelined Instruction Decode
• Instruction Decode Cycle/Register Fetch
– ID/EX.A Regs[IR6…10]; ID/EX.B Regs[IR11…15]
– ID/EX.IR IF/EX.IR
– ID/EX.Imm (IF/ID.IR16)16##IF/ID.IR16…31
– Compute the condition: Regs[IF/ID.IR6..10] op 0
– Compute the branch address: IF/ID.NPC + (IF/ID.IR16)16##IF/ID.IR16…31
• Operation
– Decode the instruction and access the register files to access the registers; the
output of the general purpose registers are read into two temporary register (A
and B, part of the pipeline registers ID/EX stage) for use in latter clock cycles
– The lower 16 bits of IR, stored in pipeline registers from IF/ID stage are also
sign extended and stored into temporary register Imm (part of ID/EX pipeline
registers), for latter use
– Value IR is passed to the next stage of pipeline registers (from IF/ID to ID/EX)
– Compute the values for the cond and branch target and use them to set the PC if
necessary (if taken branch)
27. References
• “Computer Architecture – A Quantitative
Approach”, John L Hennessy & David A Patterson,
ISBN 1-55860-329-8
• “Computer Architecture”, Nicholas Charter, ISBN –
0-07-136207
Editor's Notes
As a result, when an instruction will perform a data reference, will conflict with an instruction fetch. In this example, the load instruction wants to access the memory to load data at the same time when instruction 3 wants to fetch an instruction from memory.
To solve the problem, a stall cycle is added. The effect of the pipeline bubble is actually to occupy the resources for that instruction slot as it travels through the pipeline. Performance wise, instruction 3 will not complete during clock cycle 8, but during clock cycle 9.
Sometime those diagrams are drawn with a stall occupying a whole raw, with instruction 3 being moved to the next raw. In either case, the effect is the same. The instruction 3 is not beginning execution until cycle 5.
All the instructions after ADD use the result from ADD.
The ADD instruction writes the result in register R1 only at the WB stage, but SUB instruction reads the value during its ID stage. This is what is called a data hazard. Unless precautions are taken, the SUB instruction will read the wrong value and will use it… The AND instruction is also affected by this hazard. As we can see from the figure, the write of R1 doesn’t complete until the end of clock cycle 5. Thus, the AND instruction that reads the registers in clock cycle 4 will receive the wrong results. XOR instruction operates correctly, it reads its inputs (in clock cycle 6) after the ADD has written its result (in clock cycle 5). OR instruction can also be made to work without incurring an hazard, using a simple implementation technique. The technique is to perform the register file reads in the second half of the clock cycle and the writes in the first half.
The data hazard, in certain circumstances can be solved using an implementation technique called forwarding. The idea behind the forwarding is that the result produced by ADD is not really needed by the SUB instruction until it is actually produced. If the result can be moved from where the ADD instruction produces it , the EX/MEM register, to where the SUB needs it, the ALU input latches, then the need for a stall can be avoided. Forwarding works as follow: The ALU result from EX/MEM register is always fed back to the ALU input latches If the forwarding hardware detects that the previous ALU operation has written the register corresponding to a source for the current ALU operation, control logic selects the forwarded result as the ALU input, rather than the value read from the register file. We need to forward results not only from immediately previous instruction, but possible from instructions that started two or three cycles earlier.
To optimize the branch behavior, both of the steps should be taken.
It uses a separate adder to compute the branch target address during ID. Because the branch target addition happens during ID, it will happen for all instructions. The branch condition (Regs[IF/ID.IR6…10] op 0) will also be done for all instructions. The selection of the sequential PC or the branch target PC will still occur during IF, but now it uses values from ID phase, rather than from EX/MEM register. In this case, the branch instruction is done by the end of ID phase, so EX, MEM and WB stages are not used for branch instructions anymore.