11 Jan the two performance metrics for parallel systems are mcq
Receive specifies a sending process and a local data buffer in which the transmitted data will be placed. Topics •Introduction •Programming on shared memory system (Chapter 7) –OpenMP •Principles of parallel algorithm design (Chapter 3) •Programming on large scale systems (Chapter 6) –MPI (point to point and collectives) –Introduction to PGAS languages, UPC and Chapel •Analysis of parallel program executions (Chapter 5) –Performance Metrics for Parallel Systems •Execution Time, Overhead, … Linear time invariant system. As a result, there is a distance between the programming model and the communication operations at the physical hardware level. Deadlock can occur in a various situations. Then X is: a) G2G3G4 b) G2G4 c) G1G2G4 d) G3G4. The total time for the algorithm is therefore given by: The corresponding values of speedup and efficiency are given by: We define the cost of solving a problem on a parallel system as the product of parallel runtime and the number of processing elements used. Generally, the history of computer architecture has been divided into four generations having following basic technologies −. Dimension order routing limits the set of legal paths so that there is exactly one route from each source to each destination. We formally define the speedup S as the ratio of the serial runtime of the best sequential algorithm for solving a problem to the time taken by the parallel algorithm to solve the same problem on p processing elements. Mean . Runtime library or the compiler translates these synchronization operations into the suitable order-preserving operations called for by the system specification. The problem of flow control arises in all networks and at many levels. One method is to integrate the communication assist and network less tightly into the processing node and increasing communication latency and occupancy. Program behavior is unpredictable as it is dependent on application and run-time conditions, In this section, we will discuss two types of parallel computers −, Three most common shared memory multiprocessors models are −. Cost is sometimes referred to as workor processor-time product, and a cost-optimal system is also known as a pTP-optimal system. Forward b. TS units of this time are spent performing useful work, and the remainder is overhead. Reduce costsThese goals ca… If the main concern is the routing distance, then the dimension has to be maximized and a hypercube made. Other scalability metrics. Write-miss − If a processor fails to write in the local cache memory, the copy must come either from the main memory or from a remote cache memory with a dirty block. Send and receive is the most common user level communication operations in message passing system. The program attempts to solve a problem instance of size W. With this size and available cache of 64 KB on one processor, the program has a cache hit rate of 80%. C. They set and monitor Key Performance Indicators (KPIs) to track performance against the business objectives. This is called symmetric multiprocessor. If there is no caching of shared data, sender-initiated communication may be done through writes to data that are allocated in remote memories. Since efficiency is the ratio of sequential cost to parallel cost, a cost-optimal parallel system has an efficiency of Q(1). To reduce the number of cycles needed to perform a full 32-bit operation, the width of the data path was doubled. ERP II enables extended portal capabilities that help an organization involve its customers and suppliers to participate in the workflow process. However, these two methods compete for the same resources. COMA tends to be more flexible than CC-NUMA because COMA transparently supports the migration and replication of data without the need of the OS. enterprise-grade high-performance storage system using a parallel file system for high performance computing (HPC) and enterprise IT takes more than loosely as-sembling a set of hardware components, a Linux* clone, and adding open source file ... No two customers focus on the same metrics to assess health, performance, and general functionality. Performance metrics for parallel systems. System test involves the external workings of the software from the user's perspective. If no dirty copy exists, then the main memory that has a consistent copy, supplies a copy to the requesting cache memory. We started with Von Neumann architecture and now we have multicomputers and multiprocessors. An N-processor PRAM has a shared memory unit. The solution is to handle those databases through Parallel Database Systems, where a table / database is distributed among multiple processors possibly equally to perform the queries in parallel. But using better processor like i386, i860, etc. Exclusive read (ER) − In this method, in each cycle only one processor is allowed to read from any memory location. Given an n x n pixel image, the problem of detecting edges corresponds to applying a3x 3 template to each pixel. "Quality is defined by the customer" is : An unrealistic definition of quality A user-based definition of quality A manufacturing-based definition of quality A product-based definition of quality 2. Distributed memory was chosen for multi-computers rather than using shared memory, which would limit the scalability. If required, the memory references made by applications are translated into the message-passing paradigm. Multistage networks − A multistage network consists of multiple stages of switches. Block replacement − When a copy is dirty, it is to be written back to the main memory by block replacement method. In the beginning, three copies of X are consistent. This is needed for functionality, when the nodes of the machine are themselves small-scale multiprocessors and can simply be made larger for performance. The size of a VLSI chip is proportional to the amount of storage (memory) space available in that chip. The speedup in this case is given by the increase in speed over serial formulation, i.e., 112.36/46.3 or 2.43! Caltech’s Cosmic Cube (Seitz, 1983) is the first of the first generation multi-computers. The serial runtime of a program is the time elapsed between the beginning and the end of its execution on a sequential computer. The system allowed assessing overall performance of the plant, since it covered: 1. As same cache entry can have multiple main memory blocks mapped to it, the processor must be able to determine whether a data block in the cache is the data block that is actually needed. Since the serial runtime of this operation is Q(n), the algorithm is not cost optimal. VLSI technology allows a large number of components to be accommodated on a single chip and clock rates to increase. Each processor has its own local memory unit. A programming language provides support to label some variables as synchronization, which will then be translated by the compiler to the suitable order-preserving instruction. Topology is the pattern to connect the individual switches to other elements, like processors, memories and other switches. The latter method provides replication and coherence in the main memory, and can execute at a variety of granularities. To analyze the development of the performance of computers, first we have to understand the basic development of hardware and software. These processors operate on a synchronized read-memory, write-memory and compute cycle. In worst case traffic pattern for each network, it is preferred to have high dimensional networks where all the paths are short. a. To avoid write conflict some policies are set up. Such computations are often used to solve combinatorial problems, where the label 'S' could imply the solution to the problem (Section 11.6). • Thus a two degree of freedom system has two normal modes of vibration corresponding to two natural frequencies. As multiple processors operate in parallel, and independently multiple caches may possess different copies of the same memory block, this creates cache coherence problem. All the resources are organized around a central memory bus. The stages of the pipeline include network interfaces at the source and destination, as well as in the network links and switches along the way. As it is invoked dynamically, it can handle unpredictable situations, like cache conflicts, etc. For a given problem, more than one sequential algorithm may be available, but all of these may not be equally suitable for parallelization. Now, when either P1 or P2 (assume P1) tries to read element X it gets an outdated copy. We denote speedup by the symbol S. Example 5.1 Adding n numbers using n processing elements. Indirect connection networks − Indirect networks have no fixed neighbors. Development of the hardware and software has faded the clear boundary between the shared memory and message passing camps. If TS is the serial runtime of the algorithm, then the problem cannot be solved in less than time TS on a single processing element. The speed of microprocessors has increased by more than a factor of ten per decade, but the speed of commodity memories (DRAMs) has only doubled, i.e., access time is halved. Arithmetic, source-based port select, and table look-up are three mechanisms that high-speed switches use to determine the output channel from information in the packet header. Like any other hardware component of a computer system, a network switch contains data path, control, and storage. Here, each processor has a private memory, but no global address space as a processor can access only its own local memory. The models can be enforced to obtain theoretical performance bounds on parallel computers or to evaluate VLSI complexity on chip area and operational time before the chip is fabricated. After every 18 months, speed of microprocessors become twice, but DRAM chips for main memory cannot compete with this speed. Black Box Testing; White Box Testing; System test falls under the black box testing category of software testing. The combination of a send and a matching receive completes a memory-to-memory copy. If T is the time (latency) needed to execute the algorithm, then A.T gives an upper bound on the total number of bits processed through the chip (or I/O). To improve the company profit margin: Performance management improves business performance by reducing staff turnover which helps to boost the company profit margin thus generating great business results. So, after fetching a VLIW instruction, its operations are decoded. When a write-back policy is used, the main memory will be updated when the modified data in the cache is replaced or invalidated. Effectiveness. Elements of Modern computers − A modern computer system consists of computer hardware, instruction sets, application programs, system software and user interface. The system specification of an architecture specifies the ordering and reordering of the memory operations and how much performance can actually be gained from it. In a vector computer, a vector processor is attached to the scalar processor as an optional feature. The ideal model gives a suitable framework for developing parallel algorithms without considering the physical constraints or implementation details. Performance of a computer system − Performance of a computer system depends both on machine capability and program behavior. Machine capability can be improved with better hardware technology, advanced architectural features and efficient resource management. 2. This shared memory can be centralized or distributed among the processors. Speedup is a measure that captures the relative benefit of solving a problem in parallel. Packet length is determined by the routing scheme and network implementation, whereas the flit length is affected by the network size. There is no fixed node where there is always assurance to be space allocated for a memory block. Receiver-initiated communication is done with read operations that result in data from another processor’s memory or cache being accessed. Evolution of Computer Architecture − In last four decades, computer architecture has gone through revolutionary changes. Let X be an element of shared data which has been referenced by two processors, P1 and P2. Now consider a parallel formulation in which the left subtree is explored by processing element 0 and the right subtree by processing element 1. When two nodes attempt to send data to each other and each begins sending before either receives, a ‘head-on’ deadlock may occur. This online test is useful for beginners, experienced candidates, testers preparing for job interview and university exams. Class of parallel computers can be solved is to overlap the use efficient... Isc ) inconsistency problem − than utmost developed single processor fetching a VLIW instruction its. Or code of a light replaced mechanical gears or levers: here programmers to. To successfully complete the tasks while selecting a processor wants to read element X, fetches... 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