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Now, let us discuss two related algorithms for deciding which pages to evict. The clock algorithm is one of the most popular choices. It works by keeping frames in a circular structure. (Note that this circle may be very large: a 32-bit machine with 4k pages can have up to 220 1 million frames.) When a page fault occurs, it checks the reference bit of the next frame. If that bit is zero, it evicts that page and sets its bit to 1; if the reference bit is 1, the algorithm sets the bit to 0 and advances the pointer to next frame.
An implementation which is often used in real operating systems is a segmented queue. This type of algorithm divides all existing pages into two sets of pages. The most-active one-third of all pages use a clock algorithm. After that, pages that are evicted out of the clock are moved to a "uncommon" linked list, in which we use exact LRU. This way, we approximate LRU for the frequently-referenced pages (1/3 of the page frames - fast clock algorithm), and at the same time use exact LRU on the infrequently accessed pages (2/3 of all page frames). Since the pages in the uncommon list are not accessed very frequently, it is okay if their accesses are a little slower due to some pointer manipulation.
What are the five major activities of an operating system in regard to process management? The creation and deletion of both user and system processes The suspension and res
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Take the binary number and divide it into groups of 4 bits starting from the right hand side , if no group of 4 exists fill out leading 0's, then convert each group of 4 to a hex n
Characteristics of suspend process Suspended process isn't immediately available for execution. The process may or may not be waiting on an event. For preventing t
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Q. What are the reasons for process suspension? Reasons for process suspension 1. Swapping 2. Timing 3. Interactive user request 4. Parent process request
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Define the difference between preemptive and nonpreemptive scheduling. State why strict nonpreemptive scheduling is unlikely to be used in a computer center. Preemptive schedul
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