The goals and reason of choosing parallel programming is much easier while seeing the architecture of parallel programming.
By giving a example of loop dependency easily understand for beginners as same as loop parallelization
A distributed system is a collection of independent computers that appears as a single coherent system to users. It provides advantages like cost-effectiveness, reliability, scalability, and flexibility but introduces challenges in achieving transparency, dependability, performance, and flexibility due to its distributed nature. A true distributed system that solves all these challenges perfectly is difficult to achieve due to limitations like network complexity and security issues.
This document discusses different types of dependencies that can occur in programs:
- Data dependencies occur when an instruction refers to data from a previous instruction. There are three types: true data dependencies where an instruction depends on a previous result; output dependencies where two instructions write to the same register; and anti-dependencies where an instruction depends on data that could be overwritten.
- Control dependencies occur when the execution of one instruction depends on the outcome of another instruction, such as in an if-then statement.
- Resource conflicts occur when two instructions need the same hardware resource at the same time, such as a functional unit or register, stalling execution even if the instructions do not have a data or control dependency.
Deadlock occurs when two or more competing processes are each waiting for resources held by the other, resulting in all processes waiting indefinitely. There are four conditions required for deadlock: mutual exclusion, hold and wait, no preemption, and circular wait. Techniques to prevent deadlock include attacking each condition: allowing some resources to be shared, requiring processes request all resources at start, allowing preemption of resources, and imposing a global numbering on resource requests.
Pipelining is a technique that overlaps the execution of multiple instructions. The pipeline is divided into stages connected in a pipe-like structure. Instructions enter one end and exit the other. Common stages include fetch, decode, and execute. Pipelining increases overall instruction throughput. Pipelining consists of combinational logic that performs a computation followed by a register to store results. The clock signal controls the movement of instructions between stages on each cycle. Nonuniform stage delays can limit system throughput by the speed of the slowest stage.
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
nterprocess communication (IPC) is a set of programming interfaces that allow a programmer to coordinate activities among different program processes that can run concurrently in an operating system. This allows a program to handle many user requests at the same time. Since even a single user request may result in multiple processes running in the operating system on the user's behalf, the processes need to communicate with each other. The IPC interfaces make this possible. Each IPC method has its own advantages and limitations so it is not unusual for a single program to use all of the IPC methods.
IPC methods include pipes and named pipes; message queueing;semaphores; shared memory; and sockets.
Deadlock avoidance methods analyze resource allocation to determine if granting a request would lead to an unsafe state where deadlock could occur. A deadlock happens when multiple processes are waiting indefinitely for resources held by each other in a cyclic dependency. To prevent deadlock, an operating system must have information on current resource availability and allocations, as well as future resource needs. The system only grants requests that will lead to a safe state where there are enough resources for all remaining processes and deadlock is not possible.
A distributed system is a collection of independent computers that appears as a single coherent system to users. It provides advantages like cost-effectiveness, reliability, scalability, and flexibility but introduces challenges in achieving transparency, dependability, performance, and flexibility due to its distributed nature. A true distributed system that solves all these challenges perfectly is difficult to achieve due to limitations like network complexity and security issues.
This document discusses different types of dependencies that can occur in programs:
- Data dependencies occur when an instruction refers to data from a previous instruction. There are three types: true data dependencies where an instruction depends on a previous result; output dependencies where two instructions write to the same register; and anti-dependencies where an instruction depends on data that could be overwritten.
- Control dependencies occur when the execution of one instruction depends on the outcome of another instruction, such as in an if-then statement.
- Resource conflicts occur when two instructions need the same hardware resource at the same time, such as a functional unit or register, stalling execution even if the instructions do not have a data or control dependency.
Deadlock occurs when two or more competing processes are each waiting for resources held by the other, resulting in all processes waiting indefinitely. There are four conditions required for deadlock: mutual exclusion, hold and wait, no preemption, and circular wait. Techniques to prevent deadlock include attacking each condition: allowing some resources to be shared, requiring processes request all resources at start, allowing preemption of resources, and imposing a global numbering on resource requests.
Pipelining is a technique that overlaps the execution of multiple instructions. The pipeline is divided into stages connected in a pipe-like structure. Instructions enter one end and exit the other. Common stages include fetch, decode, and execute. Pipelining increases overall instruction throughput. Pipelining consists of combinational logic that performs a computation followed by a register to store results. The clock signal controls the movement of instructions between stages on each cycle. Nonuniform stage delays can limit system throughput by the speed of the slowest stage.
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
nterprocess communication (IPC) is a set of programming interfaces that allow a programmer to coordinate activities among different program processes that can run concurrently in an operating system. This allows a program to handle many user requests at the same time. Since even a single user request may result in multiple processes running in the operating system on the user's behalf, the processes need to communicate with each other. The IPC interfaces make this possible. Each IPC method has its own advantages and limitations so it is not unusual for a single program to use all of the IPC methods.
IPC methods include pipes and named pipes; message queueing;semaphores; shared memory; and sockets.
Deadlock avoidance methods analyze resource allocation to determine if granting a request would lead to an unsafe state where deadlock could occur. A deadlock happens when multiple processes are waiting indefinitely for resources held by each other in a cyclic dependency. To prevent deadlock, an operating system must have information on current resource availability and allocations, as well as future resource needs. The system only grants requests that will lead to a safe state where there are enough resources for all remaining processes and deadlock is not possible.
Inter-process communication (IPC) allows processes to communicate and synchronize. Common IPC methods include pipes, message queues, shared memory, semaphores, and mutexes. Pipes provide unidirectional communication while message queues allow full-duplex communication through message passing. Shared memory enables processes to access the same memory region. Direct IPC requires processes to explicitly name communication partners while indirect IPC uses shared mailboxes.
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.
This document discusses superscalar processors, which can execute multiple instructions in parallel within a single processor. A superscalar processor improves performance by executing scalar instructions simultaneously. It consists of an instruction dispatch unit that routes decoded instructions to functional units, reservation stations that decouple instruction decoding from execution, and a reorder buffer that stores in-flight instructions and ensures they complete in program order. While superscalar processors can increase performance, they have limitations such as branch delays and complexity that limit scalability.
Optimistic concurrency control in Distributed Systemsmridul mishra
This document discusses optimistic concurrency control, which is a concurrency control method that assumes transactions can frequently complete without interfering with each other. It operates by allowing transactions to access data without locking and validating for conflicts before committing. The validation checks if other transactions have read or written the same data. If a conflict is found, the transaction rolls back and restarts. The document outlines the basic algorithm, phases of transactions (read, validation, write), and advantages like low read wait time and easy recovery from deadlocks and disadvantages like potential for starvation and wasted resources if long transactions abort.
A VLIW processor implements instruction level parallelism by grouping multiple operations into a single very long instruction word. The compiler statically schedules independent instructions to execute in parallel on functional units. This avoids the need for complex hardware to dynamically schedule instructions at runtime. VLIW moves the complexity to the compiler, allowing for simpler hardware that can be lower cost and lower power while achieving higher performance than RISC and CISC chips.
Learn what the Open Systems Interconnection (OSI) reference model is and how its seven layers of functions provide vendors and developers with a common language for discussing how messages should be transmitted between any two points in a telecommunication network.
: Instead of serving as protocol, the OSI model has become a teaching tool that shows how different tasks within a network should be handled in order to promote error-free data transmission.
An Introduction to the OSI ModelSource: Flickr/jonjohnson
The open system interconnection model, better known as the OSI model, is a network map that was originally developed as a universal standard for creating networks. But instead of serving as a model with agreed-upon protocols that would be used worldwide, the OSI model has become a teaching tool that shows how different tasks within a network should be handled in order to promote error-free data transmission.
These jobs are split into seven layers, each of which depends on the function’s “handed-off” from other layers. As a result, the OSI model also provides a guide for troubleshooting network problems by tracking them down to a specific layer. Here we’ll take a look at the layers of the OSI model and what functions they perform within a network.
The document discusses multithreading and how it can be used to exploit thread-level parallelism (TLP) in processors designed for instruction-level parallelism (ILP). There are two main approaches for multithreading - fine-grained and coarse-grained. Fine-grained switches threads every instruction while coarse-grained switches on long stalls. Simultaneous multithreading (SMT) allows a processor to issue instructions from multiple threads in the same cycle by treating instructions from different threads as independent. This converts TLP into additional ILP to better utilize the resources of superscalar and multicore processors.
OSI Model - Open Systems InterconnectionAdeel Rasheed
The Open Systems Interconnection (OSI) reference model has served as the most basic elements of computer networking since the inception in 1984. The OSI Reference Model is based on a proposal developed by the International Standards Organization (ISO).
Multithreading allows exploiting thread-level parallelism (TLP) to improve processor utilization. There are several categories of multithreading:
- Superscalar simultaneous multithreading interleaves instructions from multiple threads within a single out-of-order processor core to reduce idle resources.
- Coarse-grained multithreading switches between threads on long-latency events like cache misses to hide latency.
- Fine-grained multithreading interleaves threads at a finer instruction granularity in in-order cores.
- Multiprocessing physically separates threads onto multiple processor cores.
The document compares the OSI model and the TCP/IP model. The OSI model consists of 7 layers and defines a standardized protocol-independent framework. The TCP/IP model has 4 layers and was developed based on the protocols used for the Internet. Key differences are that OSI has stricter layering while TCP/IP layers are more loosely defined, and TCP/IP focuses on the specific protocols used for Internetworking while OSI aims to be protocol-independent.
This document discusses deadlocks in operating systems. It defines a deadlock as a set of blocked processes that are each holding a resource and waiting for a resource held by another process. Four conditions must be met for a deadlock to occur: mutual exclusion, hold and wait, no preemption, and circular wait. Deadlocks can be modeled using directed resource allocation graphs. Methods for handling deadlocks include prevention, avoidance, detection, and recovery.
The document discusses memory organization and hierarchy. It describes that memory enables data storage and follows the principle of locality. There are two types of locality - temporal and spatial. The memory hierarchy uses multiple memory levels with increasing access times but also sizes as the levels are further from the CPU. This structure is useful due to the principle of locality. The memory hierarchy consists of CPU registers, cache/SRAM, main memory/DRAM, local disks, and remote storage.
This document discusses threads and threading models. It defines a thread as the basic unit of CPU utilization consisting of a program counter, stack, and registers. Threads allow for simultaneous execution of tasks within the same process by switching between threads rapidly. There are three main threading models: many-to-one maps many user threads to one kernel thread; one-to-one maps each user thread to its own kernel thread; many-to-many maps user threads to kernel threads in a variable manner. Popular thread libraries include POSIX pthreads and Win32 threads.
This document discusses various inter-process communication (IPC) mechanisms in Linux, including pipes, FIFOs, and message queues. Pipes allow one-way communication between related processes, while FIFOs (named pipes) allow communication between unrelated processes through named pipes that persist unlike anonymous pipes. Message queues provide more robust messaging between unrelated processes by allowing messages to be queued until received and optionally retrieved out-of-order or by message type. The document covers the key functions and system calls for creating and using each IPC mechanism in both shell and C programming.
This document provides an overview of multicast communication concepts. It discusses IP multicast and how it allows efficient single-message delivery to groups. Reliable multicast is described as ensuring validity, integrity, and agreement even if the sender crashes. Ordered multicast can provide FIFO, causal, or total ordering guarantees for message delivery across group members. Practical implementations rely on techniques like sequence numbers, acknowledgments, and negative acknowledgments to ensure reliability and ordering.
This presentation discusses the major functions of input/output (I/O) modules. An I/O module connects peripheral devices like keyboards and printers to a computer system, interfacing both with the system bus and tailored data links. The main functions of an I/O module are to provide control and timing for data transfer, facilitate communication between the processor and connected devices, buffer input and output data, and detect errors. I/O devices are necessary for a computer system to allow interaction and data transfer with external hardware used by humans and other systems.
About real time system task scheduling basic concepts.It deals with task, instance,data sharing and their types.It also covers various important terminologies regarding scheduling algorithms.
Deadlock occurs when each transaction in a set of two or more transactions is waiting for a resource locked by another transaction in the set, resulting in a circular wait. Several approaches to handling deadlocks are discussed, including prevention protocols that impose ordering on transactions or require transactions to lock all resources in advance. Detection methods involve constructing a wait-for graph to identify cycles indicating deadlock. If detected, victim selection chooses which transactions to abort to resolve the deadlock. Timeouts provide a simple alternative where transactions waiting longer than a threshold are aborted.
Interrupts is a signal from a device attached to a computer or from a program within the computer which causes the main program that operates the computer to stop and figure out what to do next.
This document discusses various optimization techniques used in computer architecture, including instruction level parallelism, loop optimization, software pipelining, and out-of-order execution. It provides examples of how scheduling, loop transformations like unrolling and parallelization, and hiding instruction latencies through techniques like software pipelining can improve performance. Additionally, it contrasts in-order versus out-of-order execution, noting that out-of-order allows independent instructions to execute around stalled instructions for better throughput.
The document discusses instruction level parallelism (ILP) and how to exploit it through static loop unrolling. ILP refers to the inherent parallelism in a sequence of instructions that allows some to execute concurrently. Static loop unrolling makes copies of the loop body to reduce loop overhead and expose more parallelism by scheduling instructions from different iterations together. While this can improve performance, loop unrolling increases code size and register pressure and is difficult to apply when the number of iterations is unknown.
Inter-process communication (IPC) allows processes to communicate and synchronize. Common IPC methods include pipes, message queues, shared memory, semaphores, and mutexes. Pipes provide unidirectional communication while message queues allow full-duplex communication through message passing. Shared memory enables processes to access the same memory region. Direct IPC requires processes to explicitly name communication partners while indirect IPC uses shared mailboxes.
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.
This document discusses superscalar processors, which can execute multiple instructions in parallel within a single processor. A superscalar processor improves performance by executing scalar instructions simultaneously. It consists of an instruction dispatch unit that routes decoded instructions to functional units, reservation stations that decouple instruction decoding from execution, and a reorder buffer that stores in-flight instructions and ensures they complete in program order. While superscalar processors can increase performance, they have limitations such as branch delays and complexity that limit scalability.
Optimistic concurrency control in Distributed Systemsmridul mishra
This document discusses optimistic concurrency control, which is a concurrency control method that assumes transactions can frequently complete without interfering with each other. It operates by allowing transactions to access data without locking and validating for conflicts before committing. The validation checks if other transactions have read or written the same data. If a conflict is found, the transaction rolls back and restarts. The document outlines the basic algorithm, phases of transactions (read, validation, write), and advantages like low read wait time and easy recovery from deadlocks and disadvantages like potential for starvation and wasted resources if long transactions abort.
A VLIW processor implements instruction level parallelism by grouping multiple operations into a single very long instruction word. The compiler statically schedules independent instructions to execute in parallel on functional units. This avoids the need for complex hardware to dynamically schedule instructions at runtime. VLIW moves the complexity to the compiler, allowing for simpler hardware that can be lower cost and lower power while achieving higher performance than RISC and CISC chips.
Learn what the Open Systems Interconnection (OSI) reference model is and how its seven layers of functions provide vendors and developers with a common language for discussing how messages should be transmitted between any two points in a telecommunication network.
: Instead of serving as protocol, the OSI model has become a teaching tool that shows how different tasks within a network should be handled in order to promote error-free data transmission.
An Introduction to the OSI ModelSource: Flickr/jonjohnson
The open system interconnection model, better known as the OSI model, is a network map that was originally developed as a universal standard for creating networks. But instead of serving as a model with agreed-upon protocols that would be used worldwide, the OSI model has become a teaching tool that shows how different tasks within a network should be handled in order to promote error-free data transmission.
These jobs are split into seven layers, each of which depends on the function’s “handed-off” from other layers. As a result, the OSI model also provides a guide for troubleshooting network problems by tracking them down to a specific layer. Here we’ll take a look at the layers of the OSI model and what functions they perform within a network.
The document discusses multithreading and how it can be used to exploit thread-level parallelism (TLP) in processors designed for instruction-level parallelism (ILP). There are two main approaches for multithreading - fine-grained and coarse-grained. Fine-grained switches threads every instruction while coarse-grained switches on long stalls. Simultaneous multithreading (SMT) allows a processor to issue instructions from multiple threads in the same cycle by treating instructions from different threads as independent. This converts TLP into additional ILP to better utilize the resources of superscalar and multicore processors.
OSI Model - Open Systems InterconnectionAdeel Rasheed
The Open Systems Interconnection (OSI) reference model has served as the most basic elements of computer networking since the inception in 1984. The OSI Reference Model is based on a proposal developed by the International Standards Organization (ISO).
Multithreading allows exploiting thread-level parallelism (TLP) to improve processor utilization. There are several categories of multithreading:
- Superscalar simultaneous multithreading interleaves instructions from multiple threads within a single out-of-order processor core to reduce idle resources.
- Coarse-grained multithreading switches between threads on long-latency events like cache misses to hide latency.
- Fine-grained multithreading interleaves threads at a finer instruction granularity in in-order cores.
- Multiprocessing physically separates threads onto multiple processor cores.
The document compares the OSI model and the TCP/IP model. The OSI model consists of 7 layers and defines a standardized protocol-independent framework. The TCP/IP model has 4 layers and was developed based on the protocols used for the Internet. Key differences are that OSI has stricter layering while TCP/IP layers are more loosely defined, and TCP/IP focuses on the specific protocols used for Internetworking while OSI aims to be protocol-independent.
This document discusses deadlocks in operating systems. It defines a deadlock as a set of blocked processes that are each holding a resource and waiting for a resource held by another process. Four conditions must be met for a deadlock to occur: mutual exclusion, hold and wait, no preemption, and circular wait. Deadlocks can be modeled using directed resource allocation graphs. Methods for handling deadlocks include prevention, avoidance, detection, and recovery.
The document discusses memory organization and hierarchy. It describes that memory enables data storage and follows the principle of locality. There are two types of locality - temporal and spatial. The memory hierarchy uses multiple memory levels with increasing access times but also sizes as the levels are further from the CPU. This structure is useful due to the principle of locality. The memory hierarchy consists of CPU registers, cache/SRAM, main memory/DRAM, local disks, and remote storage.
This document discusses threads and threading models. It defines a thread as the basic unit of CPU utilization consisting of a program counter, stack, and registers. Threads allow for simultaneous execution of tasks within the same process by switching between threads rapidly. There are three main threading models: many-to-one maps many user threads to one kernel thread; one-to-one maps each user thread to its own kernel thread; many-to-many maps user threads to kernel threads in a variable manner. Popular thread libraries include POSIX pthreads and Win32 threads.
This document discusses various inter-process communication (IPC) mechanisms in Linux, including pipes, FIFOs, and message queues. Pipes allow one-way communication between related processes, while FIFOs (named pipes) allow communication between unrelated processes through named pipes that persist unlike anonymous pipes. Message queues provide more robust messaging between unrelated processes by allowing messages to be queued until received and optionally retrieved out-of-order or by message type. The document covers the key functions and system calls for creating and using each IPC mechanism in both shell and C programming.
This document provides an overview of multicast communication concepts. It discusses IP multicast and how it allows efficient single-message delivery to groups. Reliable multicast is described as ensuring validity, integrity, and agreement even if the sender crashes. Ordered multicast can provide FIFO, causal, or total ordering guarantees for message delivery across group members. Practical implementations rely on techniques like sequence numbers, acknowledgments, and negative acknowledgments to ensure reliability and ordering.
This presentation discusses the major functions of input/output (I/O) modules. An I/O module connects peripheral devices like keyboards and printers to a computer system, interfacing both with the system bus and tailored data links. The main functions of an I/O module are to provide control and timing for data transfer, facilitate communication between the processor and connected devices, buffer input and output data, and detect errors. I/O devices are necessary for a computer system to allow interaction and data transfer with external hardware used by humans and other systems.
About real time system task scheduling basic concepts.It deals with task, instance,data sharing and their types.It also covers various important terminologies regarding scheduling algorithms.
Deadlock occurs when each transaction in a set of two or more transactions is waiting for a resource locked by another transaction in the set, resulting in a circular wait. Several approaches to handling deadlocks are discussed, including prevention protocols that impose ordering on transactions or require transactions to lock all resources in advance. Detection methods involve constructing a wait-for graph to identify cycles indicating deadlock. If detected, victim selection chooses which transactions to abort to resolve the deadlock. Timeouts provide a simple alternative where transactions waiting longer than a threshold are aborted.
Interrupts is a signal from a device attached to a computer or from a program within the computer which causes the main program that operates the computer to stop and figure out what to do next.
This document discusses various optimization techniques used in computer architecture, including instruction level parallelism, loop optimization, software pipelining, and out-of-order execution. It provides examples of how scheduling, loop transformations like unrolling and parallelization, and hiding instruction latencies through techniques like software pipelining can improve performance. Additionally, it contrasts in-order versus out-of-order execution, noting that out-of-order allows independent instructions to execute around stalled instructions for better throughput.
The document discusses instruction level parallelism (ILP) and how to exploit it through static loop unrolling. ILP refers to the inherent parallelism in a sequence of instructions that allows some to execute concurrently. Static loop unrolling makes copies of the loop body to reduce loop overhead and expose more parallelism by scheduling instructions from different iterations together. While this can improve performance, loop unrolling increases code size and register pressure and is difficult to apply when the number of iterations is unknown.
Parallel Computing with SolrCloud: Presented by Joel Bernstein, AlfrescoLucidworks
This document summarizes Joel Bernstein's presentation on parallel SQL in Solr 6.0. The key points are:
1. SQL provides an optimizer to choose the best query plan for complex queries in Solr, avoiding the need for users to determine optimal faceting APIs or parameters.
2. SQL queries in Solr 6.0 can perform distributed joins, aggregations, sorting, and filtering using Solr search predicates. Aggregations can be performed using either map-reduce or facets.
3. Under the hood, SQL queries are compiled to TupleStreams which are serialized to Streaming Expressions and executed in parallel across worker collections using Solr's streaming API framework.
This document summarizes Joel Bernstein's presentation on parallel SQL in Solr. The key points are:
1. SQL provides an easier way for users to query Solr compared to its other complex APIs, and SQL queries can be optimized.
2. Solr 6.0 introduces a SQL interface that supports high-cardinality aggregations, distributed joins, and Solr search predicates.
3. Under the hood, SQL queries are compiled into TupleStreams and executed in parallel across worker collections using a streaming API and expressions. This allows massive throughput for queries.
The document discusses Boolean algebra and logic gates. It defines logic gates, explains their operations, and provides their logic symbols and truth tables. The types of logic gates covered are AND, OR, NOT, NOR, NAND, XOR, and XNOR. It also discusses sequential logic circuits like flip-flops, providing details on SR, JK, T, and D flip-flops including how to build them using logic gates. Additional topics covered include the difference between combinational and sequential logic circuits, Boolean theorems, sum-of-products and product-of-sums expressions, and the Karnaugh map method for simplifying logic expressions.
The document describes data flow modeling in VHDL. It discusses how data flow style architecture models hardware in terms of the movement of data over continuous time between combinational logic components. It also describes how concurrent signal assignment statements can be used to model simple combinational logic. Examples provided include half adder, full adder, comparator, multiplexer, decoder, and arithmetic logic unit designs modeled using data flow style and concurrent signal assignments.
The document is a master's thesis titled "Automatic Program Parallelization for GPU Environment". It discusses using a compiler called C2CUDA to automatically parallelize sequential C programs for execution on a GPU. The thesis presents techniques for data dependence analysis and loop transformations to expose parallelism. It also provides results of experiments parallelizing matrix operations and magnetic resonance imaging algorithms using C2CUDA. Speedups of up to 58x were achieved for the parallelized applications compared to sequential execution.
Cursors in SQL procedures allow defining a result set that can be iterated through row by row. A cursor acts as a pointer to each row in the result set. To use a cursor, it must be declared to define the result set, opened to establish the result set, rows must be fetched from the cursor one at a time into variables, and the cursor closed once complete. The example demonstrates declaring a cursor for a SELECT statement, fetching rows and summing a value, and closing the cursor to return the result.
Cursors in SQL procedures allow defining a result set that can be iterated through row by row. A cursor acts as a pointer to each row in turn. To use a cursor, it must be declared to define the result set, opened to establish the set, individual rows can then be fetched and processed one at a time using variables, and the cursor is closed once complete. Basic cursor usage involves the DECLARE, OPEN, FETCH and CLOSE statements. An example demonstrates summing the salaries from an employee table by declaring a cursor over it, fetching rows into a variable and accumulating the sum in a loop.
The document discusses parallel programming concepts like synchronization and data parallelism. It provides examples of regularly parallelizable problems like matrix multiplication and SOR that can divide the data among processors. Irregular problems like molecular dynamics also have parallelizable loops but require more sophisticated partitioning due to load balancing issues from varying neighbor counts per molecule. Synchronization is needed between loops to ensure correct parallel execution.
The document describes the design and simulation of half adders, full adders, multiplexers, and demultiplexers using VHDL. It includes block diagrams, truth tables, and VHDL code for implementing these circuits using dataflow, behavioral, and structural modeling in Xilinx ISE. Code examples and output waveforms are provided for half adders, full adders, 4-to-1 multiplexers, and 1-to-4 demultiplexers. The aim is to learn how to design and simulate basic digital circuits using different VHDL modeling approaches.
Pavlo Zhdanov "Mastering solid and base principles for software design"LogeekNightUkraine
The document discusses SOLID principles and other principles of software design including single responsibility, open/closed, Liskov substitution, interface segregation, and dependency inversion. It provides definitions and examples of each. The SOLID principles aim to create simple, modular, and understandable code by establishing best practices for class design. Additional design principles discussed ensure reusable, cohesive components with stable dependencies and abstractions.
This document describes digital systems and processes in VHDL. It includes sections on implicit and explicit processes, comparison and selection in explicit processes, and a case study on using an explicit process to implement an asynchronous reset register with a clock and enable signal. Examples are provided of implicit process assignments, explicit processes using if/else statements and case statements, and shift registers with asynchronous reset. Templates for common constructs like registers and counters using explicit processes are also shown from Quartus II.
Christoph Koch is a professor of Computer Science at EPFL, specializing in data management. Until 2010, he was an Associate Professor in the Department of Computer Science at Cornell University. Previously to this, from 2005 to 2007, he was an Associate Professor of Computer Science at Saarland University. Earlier, he obtained his PhD in Artificial Intelligence from TU Vienna and CERN (2001), was a postdoctoral researcher at TU Vienna and the University of Edinburgh (2001-2003), and an assistant professor at TU Vienna (2003-2005). He has won Best Paper Awards at PODS 2002, ICALP 2005, and SIGMOD 2011, an Outrageous Ideas and Vision Paper Award at CIDR 2013, a Google Research Award (in 2009), and an ERC Grant (in 2011). He is a PI of the FET Flagship Human Brain Project and of NCCR MARVEL, a new Swiss national research center for materials research. He (co-)chaired the program committees of DBPL 2005, WebDB 2008, ICDE 2011, VLDB 2013, and was PC vice-chair of ICDE 2008 and ICDE 2009. He has served on the editorial board of ACM Transactions on Internet Technology and as Editor-in-Chief of PVLDB.
Number Systems - Arithmetic Operations - Binary Codes- Boolean Algebra and Logic Gates - Theorems and Properties of Boolean Algebra - Boolean Functions - Canonical and Standard Forms - Simplification of Boolean Functions using Karnaugh Map - Logic Gates – NAND and NOR Implementations.
This document provides an overview of VHDL including libraries and types, conditional statements like WHEN ELSE and WITH SELECT, processes, components, testbenches and simulation. It discusses libraries, entity-architecture structure, data types, operators, objects like signals and variables. It also covers various VHDL constructs like if-then-else, case, for loops, processes, and how to describe combinational circuits.
The document describes the implementation of 16-bit and 64-bit shift registers using VHDL in data flow modeling. It includes the VHDL code, test bench, and simulation results for shift registers that shift the values in the input register right by 1 bit position on the positive edge of the clock. The 16-bit shift register outputs the shifted value on q1 and the 64-bit shift register outputs the shifted value on q2. The design and functionality of both shift registers are verified through simulation.
Normalization is the process of organizing data in a database to reduce data redundancy and improve data integrity. It involves separating relations into smaller relations and linking them through relationships. The normal forms, such as first normal form, second normal form, etc. are used to reduce redundancy and anomalies like insertion, update and deletion anomalies. Some key aspects are that first normal form disallows multi-valued attributes and composite attributes. Second normal form eliminates non-prime attributes in relations that depend on part of a composite primary key.
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A Visual Guide to 1 Samuel | A Tale of Two HeartsSteve Thomason
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Beyond Degrees - Empowering the Workforce in the Context of Skills-First.pptx
Parallel programming concept dependency and loop parallelization
1. PARALLEL PROGRAMMING CONCEPT
DEPENDENCY AND LOOP
PARALLELIZATION
•Parallel programming concept and
their examples
•Dependency and their two types
with examples
•Loop parallelism and their types
with examples
R.AISHWARYA
4. • Simultaneous use of multiple compute
resources to solve a computational problem
• Compute resources
• Primary reasons
• Best practices
• Goals
• Steps
9. •Find dependencies within iterations of a loop
•Goal of determining different relationships
between statements.
•To allow multiple processors to work on different
portions of the loop in parallel
•First analyze the dependencies within individual
loops.
•It help determine which statements in the loop
need to be completed before other statements
can start.
•Two general categories of dependencies: Data and
Control dependency
11. DATA DEPENDENCY
TYPE NOTATION DESCRIPTION
True (Flow) Dependence
S1 ->T S2
A true dependence between S1
and S2 means that S1 writes
to a location later read from
by S2
Anti Dependence S1 ->A S2
An anti-dependence between
S1 and S2 means that S1 reads
from a location later written
to by S2.(before)
Output Dependence S1 ->I S2
An input dependence between
S1 and S2 means that S1 and
S2 read from the same
location.
12. EXAMPLES
True dependence
S0: int a, b;
S1: a = 2;
S2: b = a + 40;
S1 ->T S2, meaning that S1 has a true dependence on S2 because
S1writes to the variable a, which S2 reads from.
Anti-dependence
S0: int a, b = 40;
S1: a = b - 38;
S2: b = -1;
S1 ->A S2, meaning that S1 has an anti-dependence on S2
because S1reads from the variable b before S2 writes to it.
Output-dependence
S0: int a, b = 40;
S1: a = b - 38;
S2: a = 2;
S1 ->O S2, meaning that S1 has an output dependence on S2
because both write to the variable a.
13. CONTROL DEPENDENCY
if(a == b)
then
{
c = “controlled”;
}
d=“not
controlled”;
if(a == b)
then
{
}
c = “controlled”;
d=“not
controlled”;
if(a == b)
then
{
c = “controlled”;
d=“not
controlled”;
}
14. DEPENDENCY IN LOOP
Loops can have two types of dependence:
•Loop-carried
dependency
•Loop-independent
dependency
15. LOOP CARRIED DEPENDENCY
• In loop-carried dependence, statements in an
iteration of a loop depend on statements in
another iteration of the loop.
for(i=0;i<4;i++)
{
S1: b[i]=8;
S2: a[i]=b[i-1] + 10;
}
16. LOOP INDEPENDENT DEPENDENCY
• In loop-independent dependence, loops have
inter-iteration dependence, but do not have
dependence between iterations.
• Each iteration may be treated as a block and
performed in parallel without other
synchronization efforts.
for (i=0;i<4;i++)
{
S1: b[i] = 8;
S2: a[i] =b[i] + 10;
}
17. for (i=1; i<4; i++)
for (j=1; j<4; j++)
S3: a[i][j] = a[i][j-1] + 1;
Node : Point in the iteration space
Directed Edge: Dependency
Node: Point in the iteration space
Directed Edge: next point that will
be encountered
after the current point is
traversed
19. •Extraction parallel tasks from loops
•Data is stored in random access data structures
•A program exploiting loop-level parallelism will use
multiple threads or processes which operate on same time
•It provides speedup
•Amdhal’s law
20. Examples of Loop
parallelization
for (int i = 0; i < n; i++)
{
S1: L[i] = L[i] + 10;
}
for (int i = 1; i < n; i++)
{
S1: L[i] = L[i - 1] + 10;
}
21. Can the following Loop be made
Parallel?
for (i=1;i<=100;i=i+1)
{
A[i+1] = A[i] + C[i]; /*S1*/
B[i+1] = B[i] + A[i+1]; /*S2*/
}