1) What is the first step in problem-solving? A) Writing code B) Debugging C) Understanding the problem D) Optimizing the solution Answer: C 2) Which of these is not a step in the problem-solving process? A) Algorithm development B) Problem analysis C) Random guessing D) Testing and debugging Answer: C 3) What is an algorithm? A) A high-level programming language B) A step-by-step procedure to solve a problem C) A flowchart D) A data structure Answer: B 4) Which of these is the simplest data structure for representing a sequence of elements? A) Dictionary B) List C) Set D) Tuple Answer: B 5) What does a flowchart represent? A) Errors in a program B) A graphical representation of an algorithm C) The final solution to a problem D) A set of Python modules Answer: B 6) What is pseudocode? A) Code written in Python B) Fake code written for fun C) An informal high-level description of an algorithm D) A tool for testing code Answer: C 7) Which of the following tools is NOT commonly used in pr...
Swap-Space Management
* Modern systems typically swap out pages as required, other than swapping out entire processes. Hence the swapping system is bit of the virtual memory management system.
* Managing swap space is clearly an important task for modern OSes.
Swap-Space Use
* The amount of swap space required by an OS varies greatly according to how it is used. Some systems require an amount equal to physical RAM; some want a more of that; some want an amount same to the amount by which virtual memory exceeds physical RAM, and some systems use less or none at all!
* Some systems support more swap spaces on separate disks in order to speed up the virtual memory system.
Swap-Space Location
Swap space can be visibally located in one of two locations:
* As a large file which is part of the regular file system. This is easy to implement, but
inefficient. Not only must the swap space be processed through the directory system, the file is also subject to fragmentation issues. Caching the block location helps in detecting the physical blocks, but that is not a complete fix.
* As a raw partition, possibly on a single or little-used disk. This permits the OS more control over swap space management, which is usually faster and more efficient.
Fragmentation of swap space is generally not a big issue, as the space is retrieved every time the system is rebooted. The downside of placing swap space on a raw splitting is that it can only be grown by resplittening the hard drive.
Swap-Space Management: An Example
* Historically OSes swapped out entire processes as required. Modern systems swap out only individual pages, and only as required. (For example process code blocks and other blocks that have not been moved since they were originally loaded are normally just freed from the virtual memory system rather than copying them to swap space, because it is speeder to go detect them again in the file system and read them back in from there than to
write them out to swap space and then read them again.)
* In the mapping system shown below for Linux systems, a map of swap space is kept in memory, where each entry matches to a 4K block in the swap space. Zeros implies free slots and non-zeros refer to how many processes have a mapping to that particular block (>1 for shared pages only.)
