What is Amdahl's law and how does it relate to parallel computing?

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What is Amdahl's law and how does it relate to parallel computing?

Amdahl's law is a formula that quantifies the potential speedup of a program when executing a portion of it in parallel. It was proposed by computer architect Gene Amdahl in 1967. The law states that the overall speedup of a program is limited by the fraction of the program that cannot be parallelized.

Mathematically, Amdahl's law can be expressed as:

Speedup = 1 / [(1 - P) + (P / N)]

Where:
- Speedup represents the improvement in performance achieved by parallelizing a program.
- P is the fraction of the program that can be parallelized.
- N is the number of processors or threads used for parallel execution.

According to Amdahl's law, even if a small portion of the program cannot be parallelized, it significantly limits the potential speedup. As the number of processors or threads increases, the impact of the non-parallelizable portion becomes more pronounced.

This law highlights the importance of identifying and optimizing the parallelizable parts of a program to achieve maximum performance gains in parallel computing. It emphasizes the need for careful analysis and design to minimize the non-parallelizable portion and make efficient use of available resources. Amdahl's law serves as a guideline for understanding the trade-offs between parallelization efforts and potential speedup in parallel computing systems.