## What do you mean by parallel algorithm?

In computer science, a parallel algorithm, as opposed to a traditional serial algorithm, is an algorithm which can do multiple operations in a given time. It has been a tradition of computer science to describe serial algorithms in abstract machine models, often the one known as random-access machine.

## What is the purpose of parallel algorithms?

An algorithm is a sequence of steps that take inputs from the user and after some computation, produces an output. A parallel algorithm is an algorithm that can execute several instructions simultaneously on different processing devices and then combine all the individual outputs to produce the final result.

**What are parallel algorithm models?**

In data parallel model, tasks are assigned to processes and each task performs similar types of operations on different data. Data parallelism is a consequence of single operations that is being applied on multiple data items. Data-parallel model can be applied on shared-address spaces and message-passing paradigms.

**Where are parallel algorithms used?**

Message passing is the most commonly used parallel programming approach in distributed memory systems. Here, the programmer has to determine the parallelism. In this model, all the processors have their own local memory unit and they exchange data through a communication network.

### What are the issues with parallel algorithm?

Communication issues: Here, focus will be on the following two issues; Channel structure: Channel structure links (direct or indirect) tasks that require data (consumers) with tasks that possess those data (producers). Message-passing structure: We specify the message that must be sent and received on the channels.

### Which is the important factors affecting performance of parallel algorithms?

In general, major characteristics that affect parallel system performance are clock speed, size and number of registers, number of concurrent paths to memory, instruction issue rate, memory size, ability to fetch/ store vectors (or scalar data) efficiently, number of duplicate arithmetic functional units handling …

**How do you Analyse parallel algorithms?**

The performance of a parallel algorithm is determined by calculating its speedup. Speedup is defined as the ratio of the worst-case execution time of the fastest known sequential algorithm for a particular problem to the worst-case execution time of the parallel algorithm.

**What are the stages of parallel algorithm design?**

This methodology structures the design process as four distinct stages: partitioning, communication, agglomeration, and mapping.

#### What is the efficiency of a parallel algorithm?

is the time to execute the workload on N processors. being less than one. Therefore, one can find the constants a and b by observing at least two different workloads (i.e. different Nh) for the N=1 (single processor) case.

#### What techniques can be used to implement data-parallel algorithms?

Data-parallel model can be applied on shared-address spaces and message-passing paradigms. In data-parallel model, interaction overheads can be reduced by selecting a locality preserving decomposition, by using optimized collective interaction routines, or by overlapping computation and interaction.

**What is the need of parallel line algorithm?**

DDA (Digital Differential Analyzer) Line Drawing Algorithm

**Are all O(n) algorithms ’embarrassingly parallel’?**

No, take for example the task of calculating the maximum number in a list. This can easily be implemented using a sequential O (n) algorithm but is not embarrassingly parallel since in a parallel algorithm, communication between subtasks is required to get the final answer.

## How to compare two algorithms?

Tutorial Overview

## Is it possible to create a parallel hashing algorithm?

Hashing, parallel algorithm 1. Introduction (A) Several, say b, keys are readout in parallel in a single memory access. Recently, hashing as a method for fast pattern (B) Hashing AL operations, including key compari matching has been applied to many software systems sons, for b keys are performed within a single memory (e.g. LEAP [ 1) , SETL