24 Questions
What type of multiprocessors share a single centralized memory where processors have equal access to?
Symmetric (shared-memory) multiprocessors - SMP
What is a characteristic of Symmetric Multiprocessors (SMP) in terms of access time to memory?
Uniform Memory Access (UMA)
What is a potential bottleneck in Symmetric Multiprocessors (SMP)?
Memory/bus
What type of multiprocessors do not share a single centralized memory?
Multicomputers
What is the typical number of cores in a Symmetric Multiprocessor (SMP)?
32 cores or less
What is an alternative to Symmetric Multiprocessors (SMP)?
Distributed Shared Memory (DSM) multiprocessors
What type of architecture is characterized by multiple instruction streams and multiple data streams?
MIMD
Which type of computer consists of tightly coupled processors whose coordination/usage are generally controlled by a single OS and that share memory through a shared address space?
Multiprocessors
What type of memory access is characterized by a single memory space that is shared by all processors?
Uniform Memory Access (UMA)
What type of system is characterized by multiple processors that are not shared by a single memory space?
Multicomputers
What is a characteristic of Symmetric Multiprocessors (SMP)?
Multiple processors that share a single memory space
What type of memory access is characterized by different access times for different memory locations?
Nonuniform Memory Access (NUMA)
What type of system is characterized by a collection of processors that are connected using a network and do not share a common memory space?
Multicomputers
What is a key challenge in designing Symmetric Multiprocessors (SMP)?
Cache coherence
What is the main advantage of Distributed Shared Memory (DSM) architecture in terms of memory bandwidth?
It increases the memory bandwidth
Which of the following is a characteristic of Symmetric Multiprocessors (SMP)?
Uniform access times to memory
What is the main difference between Symmetric Multiprocessors (SMP) and Distributed Shared Memory (DSM)?
Memory organization
Which of the following communication models is typically used in Distributed Shared Memory (DSM) architecture?
Message passing model
What is the characteristic of Nonuniform Memory Access (NUMA) architecture?
Access time depends on the location of a data word in memory
Which of the following is a characteristic of Multicomputers?
Processors have independent memories and address spaces
What is the market share characteristic of Symmetric Multiprocessors (SMP)?
Bigger market share, both in $ and units
Which of the following is an advantage of Symmetric Multiprocessors (SMP)?
Reduced need for memory bandwidth
What is the role of caches in Symmetric Multiprocessors (SMP)?
Provide locality and replication
Which of the following communication models can also be applied to Distributed Shared Memory (DSM)?
Thread and fork-join model
Study Notes
Memory Organization
- Multiprocessors classified by their memory organization
- Symmetric (shared-memory) multiprocessors - SMP:
- 32 cores or less
- Single centralized memory with equal access for processors
- Uniform access time - UMA to all memory
- May have memory/bus bottleneck
- Use of large caches and many buses
- Distributed shared memory - DSM:
- 16-64 processor cores
- Distributed memory to increase bandwidth and reduce access latency
- Communicating data among processors is more complex
- Requires more software effort to take advantage of increased memory bandwidth
- Nonuniform memory access - NUMA
- Each node can be a small distributed system with centralized memory
SMP Architecture
- Processors share a single memory
- Uniform access times to the memory
- Suitable for systems with a small number of processors
DSM Architecture
- Processors share the same address space
- Not necessarily the same physical memory
- Suitable for systems with a large number of processors
Multicomputers
- Processors with independent memories and address spaces
- Communicate through interconnection networks
- May even be complete computers connected in a network (clusters)
Communication Models
- SMP: central memory, threads and fork-join model, open multi-processing - OpenMP, implicit communication (memory access)
- DSM: distributed memory, message passing model, message passing interface - MPI, explicit communication (message passing), synchronization problems
Market Share
- SMP: bigger market share in terms of dollars and units, multiprocessors in a chip
- Multicomputers: popularization of clusters for systems on the internet, massively parallel processors - MPP
SMP Advantages
- Large and efficient cache systems can reduce the need for memory bandwidth
- Provide some cost benefits as they need not much extra hardware, and are based on general-purpose processors - GPP
- Caches provide not only locality but also replication
This quiz covers the basics of computer architecture, focusing on memory organization and multiprocessors. It discusses different types of multiprocessors, such as symmetric and distributed memory multiprocessors.
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