Polling means that we are continually using CPU cycles to check whether any I/O is occurring or not.
However, it means the CPU is busy-waiting on any other task so as to not miss any I/O. Interrupt-driven
I/O allows the CPU to work on other tasks and handle requests on demand, however it requires a
context switch into the interrupt handler to process it. We normally favour interrupt-driven I/O for any sort of human interface device, as it is much slower than the data processing it is doing, so a few hundred
interrupts each second won’t matter. We might favour polling for high bandwidth raw data transfer
applications, as a million context switches tends to slow things down.
Titany answered the question on April 26, 2022 at 13:23
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Device controllers are generally becoming more complex in the functionality they provide
(e.g. think about the difference between implementing a serial port with a flip-flop controlled
by...
(Solved)
Device controllers are generally becoming more complex in the functionality they provide
(e.g. think about the difference between implementing a serial port with a flip-flop controlled
by the CPU and a multi-gigabit network adapter with the TCP/IP stack on the card itself).
What effect might this have on the operating system and system performance?
Date posted:
April 26, 2022
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Answers (1)
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Describe buffering in the I/O subsystem of an operating system. Give reasons why it is
required, and give a case where it is an advantage, and...
(Solved)
Describe buffering in the I/O subsystem of an operating system. Give reasons why it is
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Date posted:
April 26, 2022
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Answers (1)
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Name and describe four page replacement algorithms. Critically compare them with each other
(Solved)
Name and describe four page replacement algorithms. Critically compare them with each other
Date posted:
April 26, 2022
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Answers (1)
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Describe two virtual memory page fetch policies. Which is less common in practice? Why?
(Solved)
Describe two virtual memory page fetch policies. Which is less common in practice? Why?
Date posted:
April 26, 2022
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Answers (1)
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Enumerate some pros and cons for increasing the page size
(Solved)
Enumerate some pros and cons for increasing the page size
Date posted:
April 26, 2022
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Answers (1)
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What is thrashing? How might it be detected? How might one recover from it once detected?
(Solved)
What is thrashing? How might it be detected? How might one recover from it once detected?
Date posted:
April 26, 2022
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Answers (1)
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How does page size of a particular architecture affect working set size?
(Solved)
How does page size of a particular architecture affect working set size?
Date posted:
April 26, 2022
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Answers (1)
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What is the working set of a process?
(Solved)
What is the working set of a process?
Date posted:
April 26, 2022
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What are temporal locality and spatial locality?
(Solved)
What are temporal locality and spatial locality?
Date posted:
April 26, 2022
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What is an inverted page table? How does it compare to a two-level page table?
(Solved)
What is an inverted page table? How does it compare to a two-level page table?
Date posted:
April 26, 2022
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Answers (1)
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Describe a two-level page table? How does it compare to a simple page table array?
(Solved)
Describe a two-level page table? How does it compare to a simple page table array?
Date posted:
April 26, 2022
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Answers (1)
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Some TLBs support address space identifiers (ASIDS), why?
(Solved)
Some TLBs support address space identifiers (ASIDS), why?
Date posted:
April 26, 2022
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Answers (1)
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Describe segmentation-based virtual memory. You should consider the components of a
memory address, the segment table and its contents, and how the final physical address is
formed...
(Solved)
Describe segmentation-based virtual memory. You should consider the components of a
memory address, the segment table and its contents, and how the final physical address is
formed in your answer
Date posted:
April 26, 2022
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Answers (1)
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Give some advantages of a system with page-based virtual memory compared to a simply system with base-limit registers that implements swapping
(Solved)
Give some advantages of a system with page-based virtual memory compared to a simply system with base-limit registers that implements swapping
Date posted:
April 26, 2022
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Answers (1)
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Describe page-based virtual memory. You should consider pages, frames, page
tables, and Memory Management Units in your answer
(Solved)
Describe page-based virtual memory. You should consider pages, frames, page
tables, and Memory Management Units in your answer
Date posted:
April 26, 2022
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Answers (1)
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Base-limit MMUs can support swapping. What is swapping? Can swapping permit an application requiring 16M memory to run on a machine with 8M of RAM?
(Solved)
Base-limit MMUs can support swapping. What is swapping? Can swapping permit an application requiring 16M memory to run on a machine with 8M of RAM?
Date posted:
April 26, 2022
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Answers (1)
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List and describe the four memory allocation algorithms covered in lectures. Which two of the four are more commonly used in practice?
(Solved)
List and describe the four memory allocation algorithms covered in lectures. Which two of the four are more commonly used in practice?
Date posted:
April 26, 2022
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Answers (1)
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Describe the difference between external and internal fragmentation. Indicate which of
the two are most likely to be an issues on a) a simple memory memory...
(Solved)
Describe the difference between external and internal fragmentation. Indicate which of
the two are most likely to be an issues on a) a simple memory memory management machine
using base limit registers and static partitioning, and b) a similar machine using dynamic
partitioning.
Date posted:
April 26, 2022
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Answers (1)
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Why might filesystems managing external storage devices do write-through caching (avoid buffering writes) even though there is a detrimental affect on performance
(Solved)
Why might filesystems managing external storage devices do write-through caching (avoid buffering writes) even though there is a detrimental affect on performance
Date posted:
April 26, 2022
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Answers (1)
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What does flushd do on a UNIX system?
(Solved)
What does flushd do on a UNIX system?
Date posted:
April 26, 2022
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Answers (1)