In a microkernel os many things that you normally

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Unformatted text preview: o magic! Processes & Threads 12 University of Washington State queues These are PCBs! Ready queue header head ptr tail ptr firefox (1365) emacs (948) cat (1468) ls (1470) firefox (1207) Wait queue header head ptr tail ptr   25 May 2012 There may be many wait queues, one for each type of wait (parFcular device, Fmer, message, …) Processes & Threads 13 University of Washington PCBs and state queues   PCBs are data structures   dynamically allocated inside OS memory   When a process is created:           OS allocates a PCB for it OS iniMalizes PCB (OS does other things not related to the PCB) OS puts PCB on the correct queue As a process computes:   OS moves its PCB from queue to queue   When a process is terminated:   PCB may be retained for a while (to receive signals, etc.)   eventually, OS deallocates the PCB 25 May 2012 Processes & Threads 14 University of Washington The OS kernel is not a process     25 May 2012 It’s just a block of code! (In a microkernel OS, many things that you normally think of as the operaFng system execute as user ­mode processes. But the OS kernel is just a block of code.) Processes & Threads 15 University of Washington Review: What’s “in” a process?   A process consists of (at...
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This document was uploaded on 04/04/2014.

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