Table of contents
single and double buffer formula
The processing time of each piece of data = the time for each disk to read into the buffer + the time for the buffer to be sent to the user area. The time for a single buffer = (the time for each disk to read into the buffer + the time for the buffer to be sent to the user area) × How many disk blocks + data processing time of each disk block using double buffer time = time for each disk to read into the buffer × how many disk blocks + time for the buffer to be sent to the user area + data processing time for each disk block Data processing time = time for each disk to read into the buffer + time for the buffer to be sent to the user area \\ Time to use a single buffer = (time for each disk to read into the buffer + time for the buffer to be sent to the user area) × How many disk blocks + data processing time of each disk block \\ Using double buffer time = the time for each disk to read into the buffer × how many disk blocks + the time for the buffer to be sent to the user area + the processing time of each disk block dataThe processing time of each piece of data=The time to read into the buffer per disk+The time when the buffer is sent to the user areasingle buffer time _=( Time to read into the buffer for each disk+The time when the buffer was sent to the user area )×how many disk blocks+Data processing time per block _ _double buffer time _=The time to read into the buffer per disk×how many disk blocks+The time when the buffer is sent to the user area+Data processing time per block _ _
previous years
Questions 25 and 26 in the second half of 2014
Analysis: single buffer time = (time for each disk to read into the buffer + time for the buffer to be sent to the user area) × how many disk blocks + data processing time for each disk block = (10+5)×10+2= 152 ;
Double buffer time=the time for each disk to read into the buffer×how many disk blocks+the time when the buffer is sent to the user area+the processing time of each disk block data=100+5+2= 107 ;The answer is CB ;
Questions 25 and 26 in the second half of 2015
Analysis: single buffer time = (time for each disk to read into the buffer + time for the buffer to be sent to the user area) × how many disk blocks + data processing time for each disk block = (15+5)×10+1= 201 ;
Double buffer time=the time for each disk to read into the buffer×how many disk blocks+the time when the buffer is sent to the user area+the processing time of each disk block data=150+5+1= 156 ;The answer is DC ;
Multi-level index structure formula
The maximum length of the first-level index file: disk block size ( B ) each block number takes ( B ) × disk size ( B ) ÷ 1024 the second-level index file maximum length: ( disk block size ( B ) each block number takes ( B ) ) 2 × disk size ( B ) ÷ 1024 The maximum length of the first-level index file: \frac{disk block size (B)}{each block number needs to occupy (B)}×disk size (B)÷1024\ \ The maximum length of the secondary index file: (\frac{disk block size (B)}{each block number needs to occupy (B)})^2×disk size (B)÷1024The maximum length of the primary index file :Each block number takes ( B ) _Disk block size ( B )×disk size ( B )÷1024Secondary index file maximum length : (Each block number takes ( B ) _Disk block size ( B ))2×disk size ( B )÷1024
previous years
28 questions in the first half of 2009
Analysis diagram
The answer is D
Questions 27 and 28 in the second half of 2010
Analysis: According to the formula, the maximum length of the primary index file is **(512÷3)×512÷1024=85**The
maximum length of the secondary index file is (512÷3)^2×512÷1024= 14450Answer: AC ;
Questions 27 and 28 in the second half of 2012
Analysis diagram
The answer is CD ;
26 questions in the second half of 2017
Analysis: The maximum length of the secondary index file is (1024÷3)^2×1024÷1024= 116281
The answer is C ;
28 questions in the second half of 2018
Analysis diagram
The answer is B ;
Questions 25 and 26 in the second half of 2020
Analysis diagram
The answer is BD ;