28 Questions
What is a necessary requirement for efficient implementation of a NUMA system?
Hardware support
What is a characteristic of the message passing model of communication?
Threads communicate by sending and receiving messages
What is the primary advantage of using the message passing model?
It enables the connection of commodity systems to form a large parallel machine
How do threads communicate in the message passing model?
By sending and receiving messages
What is a popular software library for implementing the message passing model?
MPI
What is a key difference between the shared address space model and the message passing model?
The message passing model uses a shared address space, while the shared address space model uses message passing
What is a potential disadvantage of using the NUMA architecture?
It is expensive
What is a key advantage of the message passing model?
It allows for the connection of commodity systems to form a large parallel machine
What is a characteristic of the NUMA architecture?
Any processor can access any address in the system
What is a key challenge in implementing the message passing model?
Reasoning about locality for performance
What is the characteristic of the data-parallel model?
Very rigid computation structure
What is the foreach construct equivalent to in the data-parallel model?
A map function
What is the main characteristic of the shared address space model?
All threads can read and write to all shared variables
What is the significance of the Connection Machine (CM-1, CM-2) in the history of parallel computing?
It had thousands of processors, one instruction decode unit
What is the benefit of using the data-parallel model in MATLAB?
It allows for the same operation on each element of an array
What is the significance of the Cray supercomputers in the history of parallel computing?
They had vector processors
What is the main advantage of using SPMD programming in the data-parallel model?
It allows for implicit synchronization at the end of the map
What is the main difference between the data-parallel model and the message-passing model?
Message-passing model has highly structured communication
What is the primary mechanism of communication in the shared address space model?
Reading and writing to shared variables
What is the purpose of synchronization primitives in the shared address space model?
To ensure thread safety
How do threads communicate in the shared address space model?
Implicitly through memory operations
What is an example of a shared variable in the shared address space model?
A shared array
Why is the shared address space model a natural extension of sequential programming?
Because it assumes a shared address space
What is the role of locks in the shared address space model?
To ensure thread safety
How do threads access shared variables in the shared address space model?
By reading and writing directly
What is a characteristic of the shared address space model?
Implicit communication through memory operations
What is the purpose of the shared address space model?
To provide a natural extension of sequential programming
What is a benefit of using the shared address space model?
Simplified communication between threads
Study Notes
Parallel Programming Models
- There are three models of communication: Shared Address Space, Message Passing, and Data-Parallel.
Shared Address Space Model
- Threads communicate by reading and writing to shared variables.
- Shared variables are like a big bulletin board, where any thread can read or write to shared variables.
- Synchronization primitives are also shared variables, such as locks.
- Threads communicate implicitly through memory operations.
- This model is a natural extension of sequential programming, but requires hardware support to implement efficiently.
Message Passing Model
- Threads operate within their own private address spaces.
- Threads communicate by sending and receiving messages.
- A message includes a recipient, a buffer to be transmitted, and an optional message identifier (or "tag").
- Sending messages is the only way to exchange data between threads.
- Message passing is a programming model for clusters, where commodity systems can be connected to form a large parallel machine.
Data-Parallel Model
- The model imposes a very rigid computation structure, where programs perform the same function on different data elements in a collection.
- Historically, it was used for SIMD (Single Instruction, Multiple Data) supercomputers and vector processors.
- Today, it often takes the form of SPMD (Single Program, Multiple Data) programming, where a function is applied to each element of a collection independently.
- Synchronization is implicit at the end of the map (or loop).
- Examples include Matlab and ISPC (Intermediate-Scale Parallel Computing).
Learn about the three models of communication in parallel programming: Shared Address Space, Message Passing, and Data-Parallel. This quiz covers the fundamentals of parallel computing.
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