CGS 3763 Operating Systems Concepts Spring 2013 Dan C. Marinescu Office: HEC 304 Office hours: M-Wd 11: :30 AM

Last time:  Examples of client-server systems: Web  Heterogeneous systems  Remote Procedure call Today:  Answers to student questions from last week’s lectures  Threads Next time Reading assignments  Chapter 4 of the textbook  Chapters 4 textbook slides Lecture 17 – Friday, February 15, Lecture 17

Questions from February 4th lecture 1. Which process is faster message passing or shared memory? 2. What are the advantages and disadvantages between message passing and shared memory? 3. More explanation on the Operating System Shell and C Shell. 4. What is the difference between child processes and threads? 5. More concepts on asynchronicity would help me better to analysis this topic. 6. How does interprocess communication come into play with the processes? 7. Are the fork and exec commands only in UNIX? Lecture 173

Questions from February 6 lecture More explanations of blocking and non-blocking messages. How does non-blocking increase optimization? More explanations of Hourglass Architecture. More on the idea of multiplexing and de-multiplexing. Does multiplexing and de-multiplexing compress data, or do something else? Is peer-to-peer different that point-to-point communication? If so, what are advantages of each? Are Sockets used in all network/internet communications or just some? What are the benefits of using asynchronous communication instead of synchronous?And the opposite? Lecture 174

Questions from February 8 lecture Message buffering Is IPV6 better than IPV4? If so, what makes it better? What does the Data Link Layer consist of? More example of how RPC’s differ from other procedure calls. Are there any benefits to using encapsulation versus decapsulation methods? Lecture 175

Threads Thread  the smallest sequence of programmed instructions that can be managed independently by an operating system scheduler  a light-weight process  multiple threads can share the same address space On a single processor, multithreading generally occurs by time- division multiplexing, the processor switches between different threads. This context switching generally happens frequently enough that the user perceives the threads or tasks as running at the same time. On a multiprocessor or a multi-core system the threads actually run at the same time, with each processor or core running a particular thread or task Lecture 176

Single- and multi-threaded processes Lecture 177