9618 · 15.1
Processors, Parallel Processing and Virtual Machines flashcards
Revision flashcards for Cambridge 9618 Processors, Parallel Processing and Virtual Machines (syllabus 15.1). Flip, recall, then mark a real past-paper question.
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What is pipelining?
A technique used in processor design where instruction processing is broken down into stages (e.g., Fetch, Decode, Execute). Multiple instructions can be in different stages of completion simultaneously, increasing instruction throughput.
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What is a structural hazard in pipelining?
A conflict that occurs when two or more instructions in the pipeline require the same hardware resource at the same time. For example, two instructions trying to access memory simultaneously.
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What is a data hazard in pipelining?
A conflict that occurs when an instruction depends on the result of a previous instruction that is not yet complete. For example, `ADD R1, R2, R3` followed by `SUB R4, R1, R5`.
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What is a control hazard (or branch hazard)?
A conflict that occurs when the pipeline fetches and starts executing the next sequential instruction, but a branch instruction (like a jump or conditional loop) changes the program counter to a different location.
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Define a multi-core processor.
A single integrated circuit (chip) that contains two or more independent processing units, called 'cores'. Each core can execute its own instructions, enabling true parallel processing.
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Distinguish between SIMD and MIMD.
SIMD (Single Instruction, Multiple Data) applies one operation to many data items at once (e.g., GPU). MIMD (Multiple Instruction, Multiple Data) allows different cores to execute different instructions on different data simultaneously (e.g., multi-core CPU).
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What is a massively parallel computer?
A computer with a very large number of processors (often hundreds or thousands) that work together in parallel. They are typically MIMD or SIMD and are used for high-performance computing tasks like scientific simulations.
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What is a Virtual Machine (VM)?
A software-based emulation of a physical computer system. It runs on a host machine, has its own guest operating system, and is managed by a hypervisor.
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What is a hypervisor?
Software, firmware, or hardware that creates and manages virtual machines. It allocates and manages physical hardware resources (CPU, RAM, storage) among the various guest VMs.
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What is the difference between a Type 1 and Type 2 hypervisor?
A Type 1 (bare-metal) hypervisor runs directly on the host's hardware. A Type 2 (hosted) hypervisor runs as a software application on top of a conventional host operating system.
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What is a key advantage of using a VM for software development?
Sandboxing. A VM provides an isolated environment, so developers can test software, including potentially unstable or malicious code, without affecting the host system or other VMs.
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What is a primary disadvantage of virtualization?
Performance overhead. The hypervisor itself consumes resources (CPU, RAM), and the translation layer between the guest OS and physical hardware can introduce latency, making a VM slightly slower than a native system.