PPT-Distributed Mutex EE324 Lecture 11

Vector Clocks Vector clocks overcome the shortcoming of Lamport logical clocks L e lt L e does not imply e happened before e Goal Want ordering that matches causality. Section 8. Linux buffer cache; design principles. Outline. Thread preemption (project 2b). RPC. Linux buffer cache. Networking design principles. 12/2/10. 2. Mutex: no preemption. mutex_lock(lock). if (lock->held == 0). An Introduction to . std. ::atomic<T. >. and . the . C++. 11 Memory . M. odel. The ABC’s of Atomics. C++11 atomic operations library. Header . <atomic>. Atomic types. std. ::. atomic. <. Mines ParisTech / CRI. LAL / CNRS / IN2P3. claude.tadonki@mines-paristech.fr claude.tadonki@u-psud.fr . HISTORICAL CONTEXT. we can observe a stagnation of the (single) processor clock speed. we . need. Slides from:. . Computer . Systems: A Programmer's Perspective, 2nd Edition. by Randal E. Bryant and David R. . O'Hallaron. , Prentice Hall, 2011. . Last Lecture . Sharing. Synchronization. Critical Sections and Unsafe Regions. Ken . Birman. 1. Synchronization paradigms. We’ve looked at critical sections. Really, a form of locking. When one thread will access shared data, first it gets a kind of lock. This prevents other threads from accessing that data until the first one has finished. Jonathan Walpole. The . Structure of the . “. THE. ”. -Multiprogramming System. Edsger. W. Dijkstra. Technological University, Eindhoven, The Netherlands. Communications of the ACM, 11(5):341--346, 1968. “. THE”-. Multiprogramming System. Edsger. W. . Dijkstra. Technological University, Eindhoven, The Netherlands. Communications of the ACM, 11(5):341--346, 1968. Presented by: Amin Almassian. CS510 - Concepts of Operating Systems, Fall 2013. An Integrated Approach to Architecture and Operating Systems. Chapter 12. Multithreaded Programming and Multiprocessors. ©Copyright 2008 Umakishore Ramachandran and William D. Leahy Jr.. 12 Multithreaded Programming and Multiprocessors. CV. Last lecture. Controlling interrupts. Test . and set (atomic exchange). Compare and swap. Load linked . and . store conditional. Fetch and add . and . ticket locks. typedef. . struct. __. lock_t. systems. L-. 20. More DFS. Andrew File System. Let’s start with a familiar example: andrew. 10,000s. of . machines. 10,000s. of . people. Goal: . Have a consistent namespace for files across computers. Multiprogramming. Edsger. W. . Dijkstra. Technological University, Eindhoven, The Netherlands. System. Andrew Edwards. Goal. A . reduction . of turn-around . time for programs of short . duration. Economic . Hakim Weatherspoon. CS 3410, Spring 2013. Computer Science. Cornell University. P&H Chapter 2.11. Goals for Today. Synchronization. Threads and processes. Critical sections, race conditions, and . Lecture 10 Locks Scheduling Control: Mutex /Lock Basic pthread_mutex_t lock = PTHREAD_MUTEX_INITIALIZER; pthread_mutex_lock (&lock); x = x + 1; // or whatever your critical section is Lecture 13 Concurrency Bugs CV rules of thumb: Keep state in addition to CV’s Always do wait/signal with lock held Whenever you acquire a lock, recheck state Implementing Join with CV void thread_exit