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CS 140 Lecture Notes: Lock ImplementationSlide 1 Uniprocessor Locks void lock_acquire(struct lock *l) { intr_disable(); if (!l->locked) { l->locked = 1; } else { queue_add(&l->q, thread_current()); thread_block(); } intr_enable(); } void lock_release(struct lock *l) { intr_disable(); if (queue_empty(&l->q) { l->locked = 0; } else { thread_unblock(queue_remove(&l->q)); } intr_enable(); } struct lock { int locked; struct queue q; };
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CS 140 Lecture Notes: Lock ImplementationSlide 2 Multiprocessor Locks, v1 struct lock { int locked; }; void lock_acquire( struct lock *l) { while (swap(&l->locked, 1)) { /* Do nothing */ } void lock_release( struct lock *l) { l->locked = 0; }
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CS 140 Lecture Notes: Lock ImplementationSlide 3 Multiprocessor Locks, v2 struct lock { int locked; struct queue q; }; void lock_acquire( struct lock *l) { if (swap(&l->locked, 1)) { queue_add(&l->q, thread_current()); thread_block(); } void lock_release( struct lock *l) { if (queue_empty(&l->q) { l->locked = 0; } else { thread_unblock( queue_remove(&l->q)); }
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CS 140 Lecture Notes: Lock ImplementationSlide 4 Multiprocessor Locks, v3 struct lock { int locked; struct queue q; int sync; }; void lock_acquire( struct lock *l) { while (swap(&l->sync, 1)) { /* Do nothing */ } if (!l->locked) { l->locked = 1; l->sync = 0; } else { queue_add(&l->q, thread_current()); l->sync = 0; thread_block(); } void lock_release( struct lock *l) { while (swap(&l->sync, 1)) { /* Do nothing */ } if (queue_empty(&l->q) { l->locked = 0; } else { thread_unblock( queue_remove(&l->q)); } l->sync = 0; }
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CS 140 Lecture Notes: Lock ImplementationSlide 5 Multiprocessor Locks, v4 struct lock { int locked; struct queue q; int sync; }; void lock_acquire( struct lock *l) { intr_disable(); while (swap(&l->sync, 1)) { /* Do nothing */ } if (!l->locked) { l->locked = 1; l->sync = 0; } else { queue_add(&l->q, thread_current()); l->sync = 0; thread_block(); } intr_enable(); } void lock_release( struct lock *l) { intr_disable(); while (swap(&l->sync, 1)) { /* Do nothing */ } if (queue_empty(&l->q) { l->locked = 0; } else { thread_unblock( queue_remove(&l->q)); } l->sync = 0; intr_enable(); }
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CS 140 Lecture Notes: Lock ImplementationSlide 6
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