Which of the following statements is incorrect for Parallel Virtual Machine…
2015
Which of the following statements is incorrect for Parallel Virtual Machine (PVM)?
- A.
The PVM communication model provides asynchronous blocking send, asynchronous blocking receive, amd non-blocking receive function
- B.
Message buffers are allocated dynamically
- C.
The PVM communication model assumes that any task can send a message to any order PVM task and that there is no limit to the size or number of such messages
- D.
In PVM model, the message order is not preserved
Attempted by 140 students.
Show answer & explanation
Correct answer: D
Answer: The incorrect statement is: In PVM model, the message order is not preserved.
Explanation:
Message ordering: PVM preserves the order of messages sent from a particular sender to a particular receiver. Messages sent by one task to another are delivered in the same order, so the claim that message order is not preserved is incorrect.
Send/receive modes: PVM supports asynchronous (non-blocking) sends and provides both blocking and non-blocking receive operations. The wording that mixes 'asynchronous' and 'blocking' is confusing; interpret it as PVM offering non-blocking send and both blocking/non-blocking receives.
Buffer allocation: PVM allocates message buffers dynamically as needed by the runtime. This is correct, but buffer usage is still bounded by system memory and transport resources.
Message size/number: Any task can send to any other task in PVM. While PVM does not impose a small fixed limit in its API, message size and the number of messages are practically limited by available memory and underlying transport constraints.
Summary: The false statement is the one claiming message order is not preserved; PVM does preserve per-sender-to-receiver message order.