Amdahl’s Law MCQs – T4Tutorials.com

What does Amdahl’s Law primarily address?
a) The potential speedup of a program by parallelizing a portion of its execution
b) The impact of memory size on system performance
c) The relationship between clock speed and processor performance
d) The effect of disk speed on overall system performance
Answer: a) The potential speedup of a program by parallelizing a portion of its execution

According to Amdahl’s Law, what is the primary factor limiting the overall speedup of a program?
a) The fraction of the program that cannot be parallelized
b) The total memory available
c) The number of CPU cores
d) The network bandwidth
Answer: a) The fraction of the program that cannot be parallelized

In Amdahl’s Law, what does the term “P” represent?
a) The portion of the program that can be parallelized
b) The total execution time
c) The total memory capacity
d) The number of processors
Answer: a) The portion of the program that can be parallelized

What does “1 – P” represent in Amdahl’s Law?
a) The portion of the program that cannot be parallelized
b) The total number of processors
c) The speedup factor
d) The amount of memory used
Answer: a) The portion of the program that cannot be parallelized

How does increasing the number of processors affect the speedup according to Amdahl’s Law?
a) The speedup increases but is limited by the non-parallelizable portion of the program
b) The speedup increases linearly with the number of processors
c) The speedup is unaffected by the number of processors
d) The speedup decreases with more processors
Answer: a) The speedup increases but is limited by the non-parallelizable portion of the program

In Amdahl’s Law, what is the impact of a program’s non-parallelizable portion on its overall performance improvement?
a) It limits the maximum achievable speedup
b) It has no impact on performance
c) It enhances performance proportionally
d) It increases memory usage
Answer: a) It limits the maximum achievable speedup

What is the mathematical expression for speedup in Amdahl’s Law?
a)

$\text{Speedup} = \frac{1}{(1 – P) + \frac{P}{N}}$

$Speedup = ( 1 - P ) + N P 1$
b)

$\text{Speedup} = P \times N$

$Speedup = P \times N$
c)

$\text{Speedup} = \frac{N}{(1 – P) + P}$

$Speedup = ( 1 - P ) + P N$
d)

$\text{Speedup} = \frac{N}{1 + P}$

$Speedup = 1 + P N$
Answer: a)

$\text{Speedup} = \frac{1}{(1 – P) + \frac{P}{N}}$

$Speedup = ( 1 - P ) + N P 1$

If a program has a parallelizable portion of 80% and is run on 4 processors, what is the theoretical maximum speedup according to Amdahl’s Law?
a) 2.5
b) 4
c) 5
d) 8
Answer: a) 2.5

According to Amdahl’s Law, what happens to the speedup if the fraction of the program that can be parallelized approaches 100%?
a) The speedup approaches the number of processors
b) The speedup becomes negligible
c) The speedup becomes zero
d) The speedup remains constant
Answer: a) The speedup approaches the number of processors

How does a higher non-parallelizable fraction affect the maximum achievable speedup?
a) It decreases the maximum achievable speedup
b) It increases the maximum achievable speedup
c) It has no effect on the maximum achievable speedup
d) It changes the memory requirements
Answer: a) It decreases the maximum achievable speedup

If a program’s non-parallelizable portion is 50% and it is run on 8 processors, what is the speedup according to Amdahl’s Law?
a) 4
b) 8
c) 5.33
d) 2.67
Answer: a) 4

Which of the following best describes the practical application of Amdahl’s Law?
a) It helps estimate the benefits of parallelizing a program and understand the limits of parallel execution
b) It determines the optimal amount of memory required for a program
c) It measures the impact of disk speed on performance
d) It calculates the efficiency of network connections
Answer: a) It helps estimate the benefits of parallelizing a program and understand the limits of parallel execution

In Amdahl’s Law, if the parallelizable portion of a program is increased, what happens to the potential speedup?
a) The potential speedup increases
b) The potential speedup decreases
c) The potential speedup remains unchanged
d) The speedup becomes unpredictable
Answer: a) The potential speedup increases

What does Amdahl’s Law assume about the workload distribution across processors?
a) It assumes that the parallelizable portion is evenly distributed across all processors
b) It assumes that the workload is equally divided among all system components
c) It assumes that all tasks are performed serially
d) It assumes no impact from workload distribution
Answer: a) It assumes that the parallelizable portion is evenly distributed across all processors

Which of the following is a limitation of Amdahl’s Law?
a) It does not account for overheads and inefficiencies in parallel processing
b) It is not applicable to modern multi-core processors
c) It is only relevant for memory-bound applications
d) It fails to consider network latency
Answer: a) It does not account for overheads and inefficiencies in parallel processing

How does adding more processors impact the speedup when the non-parallelizable portion of the program is high?
a) The speedup improves but is limited by the non-parallelizable portion
b) The speedup improves proportionally with the number of processors
c) The speedup decreases as more processors are added
d) The speedup remains unaffected by the number of processors
Answer: a) The speedup improves but is limited by the non-parallelizable portion

In Amdahl’s Law, what is the effect of reducing the parallelizable portion of a program on its speedup?
a) The speedup decreases
b) The speedup increases
c) The speedup remains the same
d) The speedup becomes infinite
Answer: a) The speedup decreases

Which factor has the most significant impact on the speedup of a program according to Amdahl’s Law?
a) The fraction of the program that is serial
b) The total amount of memory
c) The network bandwidth
d) The clock speed of the CPU
Answer: a) The fraction of the program that is serial

According to Amdahl’s Law, if a program is 90% parallelizable and is run on 16 processors, what is the maximum theoretical speedup?
a) 9
b) 16
c) 10
d) 20
Answer: a) 9

What is a common misconception about the benefits of adding more processors based on Amdahl’s Law?
a) Adding more processors will always result in linear speedup
b) Adding more processors can lead to diminishing returns if a significant portion of the program is non-parallelizable
c) The non-parallelizable portion of a program does not affect speedup
d) The speedup will improve significantly without any limits
Answer: a) Adding more processors will always result in linear speedup

How does Amdahl’s Law apply to modern multi-core processors with high levels of parallelism?
a) It still provides valuable insights but may overestimate the benefits due to additional factors like parallel overhead
b) It is no longer applicable
c) It underestimates the benefits of parallelism
d) It provides exact predictions of speedup
Answer: a) It still provides valuable insights but may overestimate the benefits due to additional factors like parallel overhead

What is the effect of reducing the fraction of a program that can be parallelized on overall performance improvement?
a) It reduces the maximum achievable speedup
b) It increases the maximum achievable speedup
c) It has no effect on performance improvement
d) It makes performance improvement unpredictable
Answer: a) It reduces the maximum achievable speedup

In Amdahl’s Law, what does the term “N” represent?
a) The number of processors used
b) The total execution time of the program
c) The size of the memory
d) The network bandwidth
Answer: a) The number of processors used

How does parallel overhead impact the speedup predicted by Amdahl’s Law?
a) It can reduce the actual speedup achieved compared to the theoretical maximum
b) It increases the theoretical maximum speedup
c) It has no impact on speedup
d) It improves the parallel efficiency
Answer: a) It can reduce the actual speedup achieved compared to the theoretical maximum

What does Amdahl’s Law suggest about the benefits of parallelizing a program with a very small parallelizable portion?
a) The benefits are limited and the maximum speedup is low
b) The benefits are significant
c) The benefits are unaffected by the size of the parallelizable portion
d) The benefits are exponential
Answer: a) The benefits are limited and the maximum speedup is low

What role does Amdahl’s Law play in understanding the efficiency of parallel computing systems?
a) It helps in understanding the limits of speedup based on parallelizable and non-parallelizable portions of the program
b) It measures the efficiency of single-core processors
c) It calculates the efficiency of disk storage
d) It assesses network performance
Answer: a) It helps in understanding the limits of speedup based on parallelizable and non-parallelizable portions of the program

What is the implication of Amdahl’s Law for systems with high parallelism but a significant serial portion of a program?
a) The speedup is limited by the serial portion, regardless of the amount of parallelism
b) The speedup is unlimited due to high parallelism
c) The serial portion has no effect on speedup
d) High parallelism negates the effect of the serial portion
Answer: a) The speedup is limited by the serial portion, regardless of the amount of parallelism

How does Amdahl’s Law influence decisions about investing in additional processors for parallel computing?
a) It highlights the diminishing returns of adding more processors when the parallelizable fraction is limited
b) It encourages unlimited expansion of processors
c) It suggests that adding more processors will always provide significant improvements
d) It emphasizes the importance of increasing memory size
Answer: a) It highlights the diminishing returns of adding more processors when the parallelizable fraction is limited

What is one practical use of Amdahl’s Law in computer architecture design?
a) To evaluate the potential benefits of increasing parallelism and assess the trade-offs involved
b) To determine the optimal memory size
c) To calculate disk speed requirements
d) To measure network performance
Answer: a) To evaluate the potential benefits of increasing parallelism and assess the trade-offs involved

In Amdahl’s Law, how does the speedup change if the parallelizable portion of a program is increased from 50% to 80% while keeping the number of processors constant?
a) The speedup increases
b) The speedup decreases
c) The speedup remains constant
d) The speedup becomes unpredictable
Answer: a) The speedup increases

What does Amdahl’s Law imply about the impact of improving parallel execution on overall program performance?
a) Improvements in parallel execution have a limited effect if a significant portion of the program is serial
b) Improvements in parallel execution always lead to proportional performance gains
c) It suggests that parallel execution will always dominate program performance
d) It implies that parallel execution improvements are irrelevant
Answer: a) Improvements in parallel execution have a limited effect if a significant portion of the program is serial

What does the concept of “diminishing returns” in Amdahl’s Law mean?
a) Additional processors provide increasingly smaller improvements in speedup when the program has a large serial portion
b) Adding more memory results in diminishing returns
c) Increasing disk speed leads to diminishing returns
d) Reducing network latency results in diminishing returns
Answer: a) Additional processors provide increasingly smaller improvements in speedup when the program has a large serial portion

How does Amdahl’s Law affect the design of parallel computing systems?
a) It influences decisions about the trade-offs between parallelism and serial execution to maximize performance
b) It determines the exact number of processors needed
c) It dictates the amount of memory required for optimal performance
d) It measures the impact of network speed on performance
Answer: a) It influences decisions about the trade-offs between parallelism and serial execution to maximize performance

What effect does a small parallelizable portion have on the efficiency of a multi-core processor system?
a) It limits the efficiency gains from additional cores
b) It increases the efficiency of multi-core systems
c) It has no effect on system efficiency
d) It improves network performance
Answer: a) It limits the efficiency gains from additional cores

How can understanding Amdahl’s Law assist in optimizing software for parallel computing environments?
a) It helps identify the limits of parallelism and the importance of reducing the serial portion of the program
b) It determines the exact amount of parallelism required
c) It calculates the optimal disk speed
d) It measures memory bandwidth requirements
Answer: a) It helps identify the limits of parallelism and the importance of reducing the serial portion of the program

Which scenario would result in the highest speedup according to Amdahl’s Law?
a) A program with a very small non-parallelizable portion running on a large number of processors
b) A program with a large non-parallelizable portion running on a few processors
c) A program with equal portions of parallelizable and non-parallelizable code
d) A program with no parallelizable portion
Answer: a) A program with a very small non-parallelizable portion running on a large number of processors

What is the significance of Amdahl’s Law in the context of designing parallel algorithms?
a) It provides insights into how much speedup can be realistically achieved given the program’s parallelizable and serial components
b) It calculates the optimal algorithm complexity
c) It determines the exact number of processors needed
d) It measures the impact of disk performance on parallel algorithms
Answer: a) It provides insights into how much speedup can be realistically achieved given the program’s parallelizable and serial components

How does Amdahl’s Law affect the evaluation of performance improvements from parallel computing innovations?
a) It emphasizes that improvements may be limited by the serial portion of the workload
b) It suggests that all innovations result in linear performance gains
c) It implies that parallel computing has no limits
d) It focuses only on memory improvements
Answer: a) It emphasizes that improvements may be limited by the serial portion of the workload

What does Amdahl’s Law suggest about the relationship between program parallelizability and overall system performance?
a) System performance is maximized when the program is highly parallelizable
b) System performance is independent of program parallelizability
c) System performance improves only with additional memory
d) System performance is limited by disk speed
Answer: a) System performance is maximized when the program is highly parallelizable

Which factor has the most impact on achieving high speedup in parallel computing according to Amdahl’s Law?
a) Reducing the serial portion of the program
b) Increasing memory size
c) Enhancing disk speed
d) Improving network bandwidth
Answer: a) Reducing the serial portion of the program

How does the concept of “scalability” relate to Amdahl’s Law?
a) Scalability is limited by the non-parallelizable portion of the workload as per Amdahl’s Law
b) Scalability increases with more memory
c) Scalability is unrelated to parallel computing
d) Scalability improves with better disk performance
Answer: a) Scalability is limited by the non-parallelizable portion of the workload as per Amdahl’s Law

In practical terms, what does Amdahl’s Law suggest for improving program performance through parallelism?
a) Focus on minimizing the serial portion to achieve better performance improvements with parallelism
b) Increase the number of processors regardless of parallelizability
c) Ignore the serial portion and focus on adding more memory
d) Enhance disk speed to improve performance
Answer: a) Focus on minimizing the serial portion to achieve better performance improvements with parallelism

How does the fraction of serial execution time affect the potential speedup of a program according to Amdahl’s Law?
a) A larger serial execution time limits the maximum speedup
b) A larger serial execution time increases the maximum speedup
c) A larger serial execution time has no effect on speedup
d) A larger serial execution time improves the system’s scalability
Answer: a) A larger serial execution time limits the maximum speedup

What does Amdahl’s Law imply about the trade-off between adding more processors and parallelizing code?
a) Adding more processors has diminishing returns if the code cannot be sufficiently parallelized
b) More processors always provide a proportional increase in performance
c) Parallelizing code is less important than adding more processors
d) Adding more processors has no impact on performance
Answer: a) Adding more processors has diminishing returns if the code cannot be sufficiently parallelized

How can Amdahl’s Law help in making decisions about system upgrades for better parallel processing?
a) By evaluating how much of the application can be parallelized and the potential impact on performance improvements
b) By focusing solely on increasing memory size
c) By determining the required disk speed
d) By measuring network efficiency
Answer: a) By evaluating how much of the application can be parallelized and the potential impact on performance improvements

How does Amdahl’s Law affect the expectations for performance gains from multi-core processors?
a) It sets realistic expectations that gains are limited by the non-parallelizable portion of the workload
b) It predicts unlimited performance gains
c) It suggests that performance gains are independent of workload characteristics
d) It assumes that all cores will provide equal performance gains
Answer: a) It sets realistic expectations that gains are limited by the non-parallelizable portion of the workload

Which scenario would lead to the most effective use of Amdahl’s Law?
a) Identifying and minimizing the serial portion of a program to maximize speedup with available processors
b) Ignoring the serial portion and focusing on memory upgrades
c) Adding processors without regard to the program’s parallelizability
d) Measuring disk performance in isolation
Answer: a) Identifying and minimizing the serial portion of a program to maximize speedup with available processors

What is a key takeaway from Amdahl’s Law regarding parallel computing?
a) The benefits of parallel computing are constrained by the portion of the program that cannot be parallelized
b) Parallel computing always results in significant performance improvements
c) The number of processors is the only factor affecting performance
d) Memory size is the most important factor for performance
Answer: a) The benefits of parallel computing are constrained by the portion of the program that cannot be parallelized

According to Amdahl’s Law, how should a programmer approach optimizing a program for parallel processing?
a) Focus on increasing the parallelizable portion of the program to maximize speedup
b) Increase the number of processors without optimizing the code
c) Improve disk speed for better performance
d) Increase memory to enhance parallel processing
Answer: a) Focus on increasing the parallelizable portion of the program to maximize speedup

What is the practical impact of Amdahl’s Law on multi-core processor performance evaluations?
a) It provides insight into the diminishing returns of adding more cores based on the program’s parallelizable fraction
b) It indicates that more cores always result in proportional performance improvements
c) It suggests that disk performance is the main factor in multi-core evaluations
d) It measures the effectiveness of network upgrades
Answer: a) It provides insight into the diminishing returns of adding more cores based on the program’s parallelizable fraction

What does Amdahl’s Law suggest about the scalability of a program with a large serial portion?
a) The scalability is limited by the serial portion, leading to diminishing returns on performance improvements
b) The scalability improves with additional processors regardless of the serial portion
c) The scalability is unaffected by the serial portion
d) The scalability is determined by the amount of memory
Answer: a) The scalability is limited by the serial portion, leading to diminishing returns on performance improvements

In the context of Amdahl’s Law, how is the term “speedup” defined?
a) The ratio of the time taken to execute a program serially to the time taken when parallelized
b) The total execution time of a program
c) The number of processors used in execution
d) The memory bandwidth
Answer: a) The ratio of the time taken to execute a program serially to the time taken when parallelized

What does Amdahl’s Law imply about the relationship between the number of processors and the speedup achieved?
a) Increasing the number of processors will yield diminishing returns if there is a significant serial portion
b) Increasing the number of processors will always result in linear speedup
c) The number of processors does not affect the speedup
d) The number of processors inversely affects the speedup
Answer: a) Increasing the number of processors will yield diminishing returns if there is a significant serial portion

What should be the primary focus when attempting to maximize the performance improvements from parallel processing, according to Amdahl’s Law?
a) Reducing the serial portion of the program
b) Increasing memory size
c) Enhancing disk speed
d) Improving network bandwidth
Answer: a) Reducing the serial portion of the program

How can Amdahl’s Law be applied to assess the potential benefits of adding more processors to a system?
a) By evaluating the impact on speedup considering both the parallelizable and non-parallelizable portions of the program
b) By measuring the exact number of processors needed
c) By calculating the optimal memory size
d) By assessing the disk speed requirements
Answer: a) By evaluating the impact on speedup considering both the parallelizable and non-parallelizable portions of the program

What does Amdahl’s Law suggest about the efficiency of a system with a program that is 100% parallelizable?
a) The efficiency approaches the number of processors used
b) The efficiency is limited by the non-parallelizable portion
c) The efficiency remains constant regardless of the number of processors
d) The efficiency becomes zero
Answer: a) The efficiency approaches the number of processors used

How can understanding Amdahl’s Law guide decisions in software optimization for parallel computing?
a) It can help prioritize efforts to minimize the serial portion of the program to maximize overall performance
b) It can guide decisions on increasing disk space
c) It can inform choices about upgrading network infrastructure
d) It can assist in optimizing memory usage
Answer: a) It can help prioritize efforts to minimize the serial portion of the program to maximize overall performance

What is the limitation of parallel processing in systems with a significant serial workload according to Amdahl’s Law?
a) The maximum achievable speedup is constrained by the serial workload
b) Parallel processing has no limitations
c) The serial workload has no impact on speedup
d) The serial workload improves performance
Answer: a) The maximum achievable speedup is constrained by the serial workload

What does Amdahl’s Law imply about the performance improvements from adding processors to a system with a fixed parallelizable fraction?
a) The performance improvements will have diminishing returns as more processors are added
b) Performance improvements will be linear with the addition of more processors
c) Performance improvements are unaffected by the number of processors
d) Performance improvements increase exponentially with more processors
Answer: a) The performance improvements will have diminishing returns as more processors are added

According to Amdahl’s Law, how can you achieve the best performance gains in a parallel computing system?
a) By minimizing the non-parallelizable portion of the workload and optimizing parallel execution
b) By increasing memory size
c) By improving disk speed
d) By adding more processors without regard to parallelizability
Answer: a) By minimizing the non-parallelizable portion of the workload and optimizing parallel execution

In the context of Amdahl’s Law, how does the serial fraction of a program affect the impact of increasing the number of processors?
a) A larger serial fraction reduces the impact of increasing the number of processors
b) A larger serial fraction enhances the impact of increasing processors
c) The serial fraction has no effect on processor impact
d) The serial fraction improves network efficiency
Answer: a) A larger serial fraction reduces the impact of increasing the number of processors

What is the role of Amdahl’s Law in understanding the practical limits of parallel processing?
a) It provides a framework for understanding how the serial portion of a program limits potential performance gains from parallelism
b) It measures the exact number of processors required for optimal performance
c) It calculates memory bandwidth requirements
d) It assesses disk speed impacts
Answer: a) It provides a framework for understanding how the serial portion of a program limits potential performance gains from parallelism

How can Amdahl’s Law help in evaluating the effectiveness of parallel computing strategies?
a) By providing a clear understanding of the limits imposed by non-parallelizable code and guiding optimization efforts
b) By calculating the exact amount of memory needed
c) By determining disk performance requirements
d) By measuring network speed improvements
Answer: a) By providing a clear understanding of the limits imposed by non-parallelizable code and guiding optimization efforts

What does Amdahl’s Law suggest about the impact of increasing parallelizable code on overall program speedup?
a) Increasing the parallelizable portion leads to higher potential speedup
b) Increasing parallelizable code has no impact on speedup
c) Increasing parallelizable code decreases potential speedup
d) The impact of parallelizable code is unpredictable
Answer: a) Increasing the parallelizable portion leads to higher potential speedup

According to Amdahl’s Law, what is the effect of adding processors to a program with a small parallelizable fraction?
a) The speedup is limited and does not increase significantly with more processors
b) The speedup increases proportionally with the number of processors
c) The number of processors has no effect on speedup
d) The speedup improves dramatically with more processors
Answer: a) The speedup is limited and does not increase significantly with more processors

In practical computing scenarios, what does Amdahl’s Law suggest about the effectiveness of parallel computing advancements?
a) The effectiveness is constrained by the proportion of the program that cannot be parallelized
b) Advancements in parallel computing are always highly effective
c) The effectiveness is independent of the program’s parallelizable fraction
d) Advancements are irrelevant to performance
Answer: a) The effectiveness is constrained by the proportion of the program that cannot be parallelized

What does Amdahl’s Law indicate about optimizing a program for parallel computing?
a) Efforts should be focused on increasing the parallelizable portion and reducing the serial portion of the program
b) Optimization should solely focus on adding more processors
c) Optimization should be centered around increasing memory size
d) Optimization should focus on improving disk performance
Answer: a) Efforts should be focused on increasing the parallelizable portion and reducing the serial portion of the program

How does the fraction of parallelizable code affect the potential benefits from parallelizing a program?
a) A higher fraction of parallelizable code leads to greater potential benefits
b) The fraction of parallelizable code has no impact on benefits
c) A higher fraction of parallelizable code decreases potential benefits
d) The benefits are unpredictable based on parallelizable code fraction
Answer: a) A higher fraction of parallelizable code leads to greater potential benefits

According to Amdahl’s Law, how should a system designer approach parallel computing improvements?
a) By balancing the parallelizable and non-parallelizable portions to optimize overall performance
b) By focusing only on increasing memory
c) By solely adding more processors without regard to program characteristics
d) By improving disk speed for better performance
Answer: a) By balancing the parallelizable and non-parallelizable portions to optimize overall performance

What practical advice does Amdahl’s Law provide for achieving efficient parallel processing?
a) Focus on reducing the serial portion of the workload and optimizing the parallelizable portion for better efficiency
b) Increase memory and disk speed for better performance
c) Ignore the serial portion and only focus on adding processors
d) Enhance network performance for improved parallel processing
Answer: a) Focus on reducing the serial portion of the workload and optimizing the parallelizable portion for better efficiency

Amdahl’s Law MCQs
By: Prof. Dr. Fazal Rehman Shamil | Last updated: September 20, 2024

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