PPT-Lecture 11 PA2 , lock, and CV

Lab 3 Demand Paging I mplement the following syscalls xmmap xmunmap vcreate vgetmem vfreemem srpolicy Deadline March 22 2015 1000 PM Demand Paging OS From the OS perspective. Slide . 1. Too Much Milk With Locks. Both threads:. struct. lock l;. .... l. ock_acquire. (&l);. if (milk == 0) . {. . . buy_milk. ();. }. lock_release. (&. l);. CS 140 Lecture Notes: Locks. Slide . 1. Too Much Milk With Locks. Both threads:. struct. lock l;. .... l. ock_acquire. (&l);. if (milk == 0) . {. . . buyMilk. ();. }. lock_release. (&. l);. CS 140 Lecture Notes: Locks. IME 20051164 Junghee Pyeon. IME 20051206 Wootaek Hwang. IME. . 20051214 Joonhyung Ahn. CONTENTS. Company & Product Overview. Company Overview. Product Overview. Business Analysis. Slide . 1. Uniprocessor . Locks. void . lock_acquire. (. struct. lock *l) {. . intr_disable. ();. if (!l->locked) {. l->locked = 1;. } else {. . queue_add. (&l->q, . Slide . 1. Uniprocessor . Locks. void . lock_acquire. (. struct. lock *l) {. . intr_disable. ();. if (!l->locked) {. l->locked = 1;. } else {. . queue_add. (&l->q, . 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. Slide . 1. Uniprocessor . Locks. void . lock_acquire. (. struct. lock *l) {. . intr_disable. ();. if (!l->locked) {. l->locked = 1;. } else {. . queue_add. (&l->q, . Concurrency. Threads. Locks. Condition Variables. Fixing atomicity violations and order violations. Semaphore. Semaphores . keep extra state, so users sometimes don’t. .. Unlike . CV, signal was not lost . 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 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 Slide . 1. Too Much Milk With Locks. Both threads:. struct. lock l;. .... l. ock_acquire. (&l);. if (milk == 0) . {. . . buyMilk. ();. }. lock_release. (&. l);. CS 140 Lecture Notes: Locks. class Lock {. Lock() {}. int locked = 0;. . ThreadQueue. q;. };. void Lock::lock() {. . intrDisable. ();. if (!locked) {. locked = 1;. } else {. . q.add. (. currentThread. Lecture 21. April . 11. th. , . 2012. Distributed Shared Memory (. con’t. ). Synchronization. Prof John D. Kubiatowicz. http://www.cs.berkeley.edu/~kubitron/cs252. Recall: Sequential Consistency of Directory Protocols.