西电计算机操作系统课程设计pintospro3

西安电子科技大学操作系统课程设计验4R报告实验名称： Priority-Scheduling--Task2班 级： 姓 名： 学 号：一、实验内容解决优先级反转的问题，在高优先级和低优先级之间竞争锁的问题。二、分析及设计使用多重优先级捐赠，解决优先级反转的问题。1、一个线程获得锁，如果获得这个锁的线程比自己低就提高它的优先级，如果这个锁也是被锁着，那就递归捐赠优先级，在线程释放掉锁之后，恢复未捐赠的优先级。2、在释放掉锁的时候，若优先级改变可以发生抢占。3、将信号量的等待队列实现为优先队列。4、将conditio^T等待队列实现为优先队列。5、一个线程被多个线程捐赠，保持当前优先级为捐赠优先级中最大值。6、在对一个线程设置优先级时，如果处于被捐赠状态，标riginal_priority进行设置，如果设置的优先级大于当前的优先级，改变当前的优先级，否则在捐赠完成时恢复original_priority。7、在释放锁对一个锁优先级有改变的时候应考虑其余被捐赠优先级和当前优先级。三、详细实现1、修改thread数据结构（thread.h）intbase_priority;产Basepriority.*/structlistlocks;/*Locksthatthethreadisholding.Vstructlock'lock_waiting:/*Thelockthatthethreadiswaitingfor.*/2、在lock结构体中添加成员（synch.h）rLock.Vstructlockstructthread'holder;/*Threadholdinglock（fordebugging）.Vstructsemaphoresemaphore;产Binarysemaphorecontrollingaccess.*/structlist_elemelem;/*Listelementforprioritydonation.*/intmax_priority;/*Maxpriorityamongthethreadsacquiringthelock.*/3、修改lock_acquire函数(synch.c)if(lock->holder!=NULL&&!thread_mlfqs)current_thread->lock_waiting=lock;I=lock;while{I&¤tjhreadapriority>l->rrax_priority)l->max_priDrity=currentthread-apriority:threaddonatepriority(l->holder);I=l->holder->lock_waiting;sema_down{&lock->semaphore);oldlevel=intrdisable();currentjhread=thread_current();if(!thread_mlfqs)currentthread->lock_waiting=NULL;lock->rriax_priority=currentjhreadapriority:thread_hold_the_lock(lock);lock->holder=currentthread;intr_set_level(oldjevel);4、thread_hold_the_lock()函数的实现voidthread_hold_the_lock(structlocklock)enumintrleveloldjevel=intrdisable();listinsertordered(&threadcurrent()->locks,&locK->elem,cmp.;NULL);if(lock->max_priority>thread_current()->priority)threadcurrent()->priority=lock->rrax_pnority:thread_yield():)5、thread_donate_priority()函数的实现voidthread_donate_priority(structthread巧enumintrleveloldlevel=intrdisable();thread_update_priority(t):if(t->status==THREAD_READY)listremove(&t->elem);list_insert_ordered(&ready_list1 cmpdNULL):intrsetlevel(oldlevel);6、锁队列排序函数lock_cmp_priority实现boolIock_cmpj3riority(conststructlist_elem*a,conststructlist_elemvoid*auxUNUSED)returnlist_entry(a,structHock,elem)->maxjorionty>list_entry(b,structlock,elem)->maxjoriority:7、在lock_release函数加入以下语句if(Ithreadmlfqs)thread_rerrove_lock(lock);8、thread_remove_lock实现voidthread_remove_lock(structlock#lock)enumintrleveloldlevel=intrdisable();listremove(&lock->elem):thread_update_priority(threadcurrent()):intrsetlevel(oldlevel);9、thread_update_priority函数实现处理当前线程的优先级voidthreadupdatejoriority(structthread*t)enumintrjeveloldjevel=intr_disable();intmax_priority=t->basejDriority;intlockjoriority;if(!list_empty(&t->locks))listsort(&t->locks,lockcmpjDriority,NULL);lockjoriority=listentry(listfront(&t->locks),structlock,elem)->maxjDriority;if(lockjDriority>maxjDriority)maxjDriority=lockjDriority;t->priority=maxjDriority;intrsetlevel(oldlevel);10、在init_thread中加入初始化t->basepriority=priority;listjnit(&t->locks);t->lock_waiting=NULL;11、修改thread_set_prioritythreadsetpriority(intnewpriority)i(if{threadrrilfqs)return;enumintrleveloldlevel=intrdisable();structthread*current_thread=threadcurrent();intoldpriority=current_thread->priority;current_thread->base_priority=newpriority;if(listempty(¤t_thread->locks)||newpriority>oldpriority)current_thread->priority=newpriorityjthread_yield();I12、把condition的队列改成优先级队列，修改cond_signal函数if(!list_empty(&cond->walters))।(listsort(&cond->walters,condsemacmppriority,NULLj；semajjp(&list_entry(list_pop_front(&cond->walters),structsemaphoreelem,elem)->semaphore);13、比较函数的实现cond_sema_cmp_priority(conststructlist_elem*a,conststructlist_elem*b.void*auxUNUSED)丈 — —structsemaphoreelem*sa=list_entry(a,structsemaphoreelem,elem):structsemaphore_elem*sb=list_entry(b,structsemaphore_elem,elem);returnlist_entry(list_front(&sa->semaphore.waiters),structthread,elem)->priority>list_entry(list_front(&sb->semaphore.waiters),structthread.elem)->priority:14、把信号量的等待队列实现为优先级队列，修改sema_up|sema_up(structsemaphore•sema)enumintrjeveloldjevel;ASSERT(sema!=NULL);oldlevel=intrdisable();rf(!list_empty(&sema->waiters))listsort(&sema->waiters,cmp,NULL);threadunblock(listentry(list_pop_front(&sema->waiters),structthread,elem));sema->value++;threadyield();intrsetlevel(oldlevel);15、修改sema_downsema_down(structsemaphore'sema)enumintr_leveloldjevel;ASSERT(sema!=NULLi；ASSERT(!intr_context()):oldjevel=intr_disable();while(sema->value==0)listjnsert_ordered(Ssema^waiters,&thread_current()->elem,cmp,NULL);thread_block();&ema->valueintr_set_level(oldjevel);四、实验结果实现结果如图，priority全部完成passtests/threads/alarm-negativepasstests/threads/priority-changepasstests/threads/priority-donate-onepasstests/threads/priority-donate-multiplepasstests/threads/priority-donate-multiple2passtests/threads/priority-donate-nestpasstests/threads/priority-donate-semapasstests/threads/priority-donate-lowerpasstests/threads/priority-fifopasstests/threads/priorit