COM ORG UNIT V

Parallel processing

Parallel processing

refers to one or more independent operating systems managing multiple processors and performing multiple tasks.

Flynn’s classification of parallel processing systems

Flynn’s classification of parallel processing systems

Single Instruction Stream Single Data Stream (SISD)

Single Instruction Stream Multiple Data Stream (SIMD)

Multiple Instruction Stream Single Data Stream (MISD)

Multiple Instruction Stream Multiple Data Stream (MIMD)

Single Instruction Stream Single Data Stream (SISD)

is a single processor system that sequentially processes an instruction and data, one at a time.

Single Instruction Stream Multiple Data Stream (SIMD)

with an instruction to simultaneously perform the same operation on multiple data. It is also called an array processor, as it enables synchronous parallel processing.

Multiple Instruction Stream Single Data Stream (MISD)

Each processing unit in the _______ parallel computing architecture runs different instructions and processes the same data.

Multiple Instruction Stream Multiple Data Stream (MIMD)

multiple processors process different programs and different data, and most parallel computers fall into this category.

Classification of parallel processing systems, according to the memory structure

Symmetric multiprocessor (SMP)

Massive parallel processor (MPP)

Non uniform memory access (NUMA)

Symmetric multiprocessor (SMP)

is a tightly-coupled system in which al processors use the main memory as the shared memory. It is easy to program since the data transfer can use shared memory.

Massive parallel processor (MPP)

is a distributed memory type in which each processor has an independent memory. The loosely coupled system exchanges data between processors through a network, such as Ethernet.

Non uniform memory access (NUMA)

is a structure the combines the advantages of the SMP which is a shared memory structure that makes it easier to develop programs and the MPP structure, which offers excellent scalability.

Types of parallel processor technology

Instruction pipelining

Pipeline hazard

Instruction pipelining

The technology improves the CPU performance by dividing an operation into several stages and configuring a hardware unit for processing each stage separately in order to process different instructions simultaneously.

four-stage instruction pipeline

fetching (IF), instruction decoding (ID), operand fetching (OF), and execution (EX).

Pipeline hazard

refers to the pipeline speed exceptionally slowing down.

Pipeline hazards include the _____, __, and, ______.

data hazard, the control hazard, and the structural hazard.

Data hazards

occur when the next instruction execution has to be delayed until the previous instruction has been completed because of the dependency between instruction operands.

Control hazards

are generated by branch instructions, like branch and jump which change the execution order of the instructions.

Structural hazards

are generated when instructions cannot be processed in parallel in the same clock cycle, due to hardware limitations.

Parallel programming technology

Compiler technology - OpenMP

Message passing parallel programming model

Load balancing technologies -AMP, SMP, and BMP

Compiler technology - OpenMP

is a compiler directive-based parallel programming API.

Message passing parallel programming model

suitable to a distributed memory system structure.

Load balancing technologies -AMP, SMP, and BMP

Load balancing adequately distributes jobs to the cores in order to increase the multi-core performance.

AMP

An OS is executed independently in each processor core.

SMP:

An OS manages al processor cores simultaneously. Application programs can operate in any core.

BMP model:

An OS manages al process cores simultaneously, and an application program can run on a specific core.

Graphic processing technology

Graphics processing unit (GPU)

General-purpose GPU (GPGPU)

Graphics processing unit (GPU)

The hardware specializes in computer graphics calculation and is mainly used for the rendering of 3D graphics.

General-purpose GPU (GPGPU)

Based on the fact that a GPU shows high computational performance in matrix and vector operations that are mostly used for graphic rendering, the computing system intends to utilize GPUs in the general computing domain as well.

Concept of storage

Computer systems use a storage unit to access data and run commands. Although a system uses main memory for the main storage unit, it uses auxiliary memory to permanently store and utilize data.

Connection of storage unit and server

Multimedia services, using a large volume of data, led to computer systems storing an increased volume of data.

Disk scheduling

that stores data is a device using a rotating magnetic disk.

Disk performance measurement indicator

include the access time, seeking time, rotational delay or rotational latency, and data transfer time.

seeking time

indicates how long it takes to move the head from the current head position, to the track containing the data.

rotational latency

indicates how long it takes from the moment the head begins rotating to move to the track containing the data, to the moment it reaches the sector that contains the data.

data transfer time

indicates how long it takes to transfer the read data to the main memory.

Circular SCAN (C-SCAN) disk scheduling

This technique moves the head by connecting the inner and outer tracks in a circular model.

Circular LOOK (C-LOOK) disk scheduling

technique that connects the inner and outer tracks in an annular model in order to make the head move.

Redundant array of independent disks (RAID) technology

is a storage technology that minimizes the factors that can cause failure, and it improves access performance by arranging a number of disks, and by creating a separate disk unit by linking them with each other.

Backup storage: LTO and VTL

Graphic compression type

It refers to a method of restoring a compressed image without information loss from the original data while decompressing. It is characterized by a lower compression rate than lossy compression. Lossy compression is also called irreversible compression.

Multimedia data

includes text, image, video, and audio data. The text has the form of plain text and non-linear hypertext.