Lecture15 - COP 4600 Operating Systems Fall 2010 Click to...

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Click to edit Master subtitle style 8/1/11 Lecture 15 COP 4600 Operating Systems Fall 2010 Dan C. Marinescu Office: HEC 439 B Office hours: Tu-Th 3:30-4:30 PM
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Lecture 15 8/1/11 n Last time: n NFS (Network File System) n Virtualization n Today: n Presentation of the paper “DNS Complexity” by Vixie n Threads, Virtual memory, Bounded buffers. Virtual Links. n Primitives for processor virtualization n Threads. The state of a thread. ¨ Thread manager. Interrupts. Interrupt handler. ¨ Race conditions and locks. ¨ Thread and processor layers ¨ Processor sharing; Scheduling; Switching the processor from one thread to another – YIELD. ¨ Implementation of YIELD and SCHEDULER n Deadlocks ¨ Next time n Thread coordination with a bounded buffer. Race conditions Lecture 15 – Tuesday October 12, 2010 22
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Lecture 15 8/1/11 Virtualization – relating physical with virtual objects n Virtualization & simulating the interface to a physical object by: 1. Multiplexing B create multiple physical objects from one instance of a physical object. 2. Aggregation ± create one virtual object from multiple physical objects 3. Emulation ^ construct a virtual object from a different type of a physical object. Emulation in software is slow. Method Physical Resource Virtual Resource Multiplexing processor thread real memory virtual memory communication channel virtual circuit processor server (e.g., Web server) Aggregation disk RAID core multi-core processor Emulation disk RAM disk system (e.g. Macintosh) virtual machine (e.g., Virtual PC) Multiplexing + Emulation real memory + disk virtual memory with paging communication channel + processor TCP protocol 33
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Lecture 15 8/1/11 Virtualization of the three abstractions. (1) Threads n Implemented by the operating system for the three abstractions: 1. Threads & a thread is a virtual processor; a module in execution 1. Multiplexes a physical processor 2. The state of a thread: (1) the reference to the next computational step (the Pc register) + (2) the environment (registers, stack, heap, current objects). 3.
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Lecture15 - COP 4600 Operating Systems Fall 2010 Click to...

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