---
title: "Multiprocessor performance and reliability"
subject: "Computer Organization and Architecture"
chapter: 8
key: "semester_5/computer_organization_and_architecture:multiprocessor-benefits"
source: https://www.bctengineer.com/q/semester_5/computer_organization_and_architecture/multiprocessor-benefits
site: BCT Engineering
---

# Multiprocessor performance and reliability

Computer Organization and Architecture · Chapter 8: Multiprocessors

- Asked in: 2073 Shrawan, 4 marks
- Answer checked by Claude Opus 5.5 (high effort) on 2026-10-14
- Page: https://www.bctengineer.com/q/semester_5/computer_organization_and_architecture/multiprocessor-benefits
- Whole chapter: https://www.bctengineer.com/md/semester_5/computer_organization_and_architecture/chapter-8

## Question

Describe how multiprocessor systems increase the performance level and reliability.

## Short answer

Multiple processors execute tasks in parallel, raising throughput up to n-fold and reducing execution time. Reliability improves because a failed processor can be bypassed, allowing graceful degradation and maintaining availability without system shutdown.

## Answer

**Performance:** several processors execute different programs, or parts of one program, at the same time (parallelism). The throughput of a system with n processors can rise by up to n times, and a large problem is finished faster by dividing it among the processors. The computation and I/O of different jobs can also overlap.

**Reliability and availability:** if one processor fails, the remaining processors can take over its work, and the system continues at reduced performance (graceful degradation) instead of stopping. Failed processors can be repaired or replaced without shutting down the whole system, and the work of memory and I/O modules can also be taken over by others through redundant paths. Hence the system is more reliable and available than a single-processor system.

Additional gain: the system can be expanded by adding processors (scalability).

## Check yourself

The answer's key points as multiple-choice questions, with the correct option and why.

1. How do multiprocessors increase performance?
   A. By running different programs or parts of one program in parallel
   B. By removing memory
   C. By lowering the clock
   D. By using one CPU
   Answer: A. Parallelism raises throughput by up to n times. (Key point: Performance)

2. What is graceful degradation?
   A. Performance doubles on a fault
   B. The system continues at reduced performance after a processor fails
   C. The system stops on any fault
   D. Memory is erased
   Answer: B. Remaining processors take over. (Key point: Graceful degradation)

3. What can be done with a failed processor?
   A. Repaired or replaced without shutting down the whole system
   B. Whole system must be rebuilt
   C. It is ignored forever
   D. Nothing
   Answer: A. This raises availability. (Key point: Repair)

## Related in Computer Organization and Architecture

- [OS configurations in multiprocessor systems](https://www.bctengineer.com/question.md?key=semester_5%2Fcomputer_organization_and_architecture%3Aos-multiprocessor) — Computer Organization and Architecture, chapter 8
- [Vector computation for performance](https://www.bctengineer.com/question.md?key=semester_5%2Fcomputer_organization_and_architecture%3Avector-computation) — Computer Organization and Architecture, chapter 4

## Related in other subjects

- [Increasing reliability of embedded real-time software](https://www.bctengineer.com/question.md?key=semester_5%2Finstrumentation_ii%3Aembedded-rt-reliability) — Instrumentation II, chapter 9
- [Gumbel design flood, 40-year life, 85% reliability](https://www.bctengineer.com/question.md?key=semester_5%2Fengineering_hydrology%3Agumbel-21yr-life40-rel85) — Engineering Hydrology, chapter 6, asked 2×
- [Second parallel pipe to increase flow](https://www.bctengineer.com/question.md?key=semester_4%2Fhydraulics%3Atwo-reservoirs-second-pipe-increase-flow) — Hydraulics, chapter 2
- [Sysadmin roles; improving OS performance](https://www.bctengineer.com/question.md?key=semester_6%2Foperating_system%3Asysadmin-roles-os-performance) — Operating System, chapter 9