End switch load the return address context context

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Unformatted text preview: WITCH # load the return address Context Context Switches: Voluntary and Involuntary On a uniprocessor, the set of possible execution schedules depend depend on when context switches can occur. • Voluntary: one thread explicitly yields the CPU to another. E.g. a thread can suspend itself with Yield It may also block to wait for some event with Sleep • Involuntary: the system scheduler suspends an active thread and and switches control to a different thread. Thread scheduler tries to share CPU fairly by timeslicing. General General Thread Operations Create allocate memory for stack, perform bookkeeping associate entry-point (called function) parent parent thread creates child threads Destroy/Cancel Destroy/Cancel release memory (or recycle), perform bookkeeping Suspend/Resume/Yield/Sleep Thread Thread Scheduling When a thread blocks or yields or is de-scheduled by the system, which one is picked to run next? Preemptive scheduling: preempt a running thread Non-preemptive: thread runs until it yields or blocks Priorities? Al...
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This document was uploaded on 04/02/2014.

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