操作系统名词解释整理

1==================================名词解释======================================Operatingsystem:operatingsystemisaprogramthatmanagesthecomputerhardware.Theoperatingsystemistheoneprogramrunningatalltimesonthecomputer(usuallycalledthekernel),withallelsebeingsystemsprogramsandapplicationprograms.操作系统：操作系统一个管理计算机硬件的程序，他一直运行着，管理着各种系统资源Multiprogramming:Multiprogrammingisoneofthemostimportantaspectsofoperatingsystems.MultiprogrammingincreasesCPUutilizationbyorganizingjobs(codeanddata)sothattheCPUalwayshasonetoexecute.多程序设计：是操作系统中最重要的部分之一，通过组织工作提高CPU利用率，保证了CPU始终在运行中。batchsystem:Abatchsystemisoneinwhichjobsarebundledtogetherwiththeinstructionsnecessarytoallowthemtobeprocessedwithoutintervention.批处理系统：将许多工作和指令捆绑在一起运行，使得它们不必等待插入，以此提高系统效率。time-sharingsystem:timesharingisalogicalextensionofbyswitchingamongthem,buttheswitchesoccursofrequentlythattheuserscaninteractwitheachprogramwhileitisrunning.分时系统：是对多道程序设计的逻辑扩展。通过在多个作业间转换CPU，可以同时执行多个作业，但是这种转换发生的如此频繁以至于用户在程序运行的同时可以与计算机交互。Real-timesystem:Areal-timesystemhaswell-defined,fixedtimeconstraints.Processingmustbedonewithinthedefinedconstraints,orthesystemwillfail.实时系统：实时系统具有明确定义的、不变的时间约束。处理过程必须在规定的时间内完成，否则系统就失效了。DMA:Itisanessentialfeatureofallmoderncomputers,asitallowsdevicestotransferdatawithoutsubjectingtheCPUtoaheavyoverhead.直接内存访问：一种不经过CPU而直接从内存存取数据的数据交换模式。Systemcall:Systemcallprovidetheinterfacebetweenarunningprogramandtheoperatingsystem.系统调用：系统调用为运行中的程序和操作系统提供了一个接口。Microkernel:themicrokernelapproachstructurestheoperatingsystembyremovingallnonessentialcomponentsfromthekernelandimplementingthemassystemanduser-levelprograms.微内核：微内核将所有不必要的组件从内核中去掉，并将它们作为系统和用户层程序来实现。Process:Itisprograminexecution。进程：一个正在运行的程序PCB:eachprocessisrepresentedintheoperatingsystembyaprocesscontrolblock(PCB).APCBcontainsmanypiecesofinformationassociatedwithaspecificprocess.PCB:操作系统通过进程控制块（PCB）表示进程，一个PCB存储了进程的许多信息。Jobscheduler:thelong-termscheduler,thejobscheduler,selectsprocesseswhicharespooledtoamass-storagedeviceandloadsthemintomemoryforexecution.2作业调度：又称长程调度，从存储器中选择进程并将其载入内存。CPUscheduler:theshort-termscheduler,selectsfromamongtheprocessesthatarereadytoexecuteandallocatestheCPUtooneofthem.CPU调度：又称近程调度，从这些进程中选择就绪进程并为之分配CPU。Thread:AthreadisbasicunitofCPUutilization;itcomprisesathreadID,aprogramcounter,aregisterset,andastack.线程：线程是一个基本的CPU执行单元；它包含了一个线程ID，一个程序计数器，一个寄存器组合一个堆栈。Throughput:onemeasureofworkisthenumberofprocessesthatarecompletedpertimeunit.吞吐量：对工作量的一种测量单位，单位时间内运行完的进程数量。nonpreemptive/preemptivescheduling:Undernonpreemptivescheduling,oncetheCPUhasbeenallocatedtoaprocess,theprocesskeepstheCPUuntilitreleasestheCPUeitherbyterminatingorbyswitchingtothewaitstate.Aformofschedulingdesignedsothatjobscanbeinterruptedandtheirresourcestransferredtomoreurgentjobs.Aninterruptedjobcanbeeitherterminatedcompletelyorresumedtater.非抢占式/抢占式调度：在非抢占式调度下，一旦CPU分配给一个进程，那么该进程就会保持CPU直到终止或转换到等待状态。抢占式调度：允许进程被中断，使其资源用在更重要的地方。Dispatcher:thedispatcheristhemodulethatgivesthecontroloftheCPUtotheprocessselectedbyshort-termscheduler.调度程序：调度程序是一个模块，他将CPU控制提交给短程调度程序选择的进程。Turnaroundtime:theintervalfromthetimeofsubmissionofaprocesstothetimeofcompletionistheturnaroundtime.周转时间：从进程提交到进程完成的时间间隔。Waitingtime:waitingtimeisthesumoftheperiodsspentwaitinginthereadyqueue.等待时间：进程在就绪队列中耗费时间的总和。Responsetime:responsetimeisthetimefromthesubmissionofarequestuntilthefirstresponseisproduced.响应时间：从进程提交到产生首次响应的时间。Criticalsection:criticalsectionisasegmentofcodeinwhichtheprocessmaybechangingcommonvariables,updatingatable,writingafile,andsoon.临界区：每个进程有一个代码段，被称之为临界区，进程在临界区内可能会修改公有变量、更新一个表、写一个文件等。Semaphore:AsemaphoreSisintegervariablethat,apartfrominitialization,isaccessedonlythroughtwostandardatomicoperations:wait()andsignal().3信号量：信号量s是一个整形数，除初始化之外，对它的访问只能通过两个标准原子操作：wait和signal。Atomicoperation:Atomicoperationmeansanoperationthatcompletesinitsentiretywithoutinterruption.原子操作：原子操作指不会被中断，一次运行完的操作。Deadlock:asetofblockedprocesseseachholdingaresourceandwaitingtoacquirearesourceheldbyanotherprocessintheset.死锁：一些进程各自拥有一个资源，同时等待着另一个已被占有的资源，造成互相锁定的情况。Starvation:starvationisasituationinwhichprocesseswaitindefinitelywithinthesemaphore.饥饿：饥饿是指一个进程在信号量中无休止的等待。Deadlockprevention:Restrainthewaysrequestcanbemade,attackingfourconditions.死锁预防：只要确保造成死锁的四个条件中任意一个不成立，就可以预防死锁。Deadlockavoidance:Adecisionismadedynamicallywhetherthecurrentresourceallocationrequestwill,ifgranted,potentiallyleadtoadeadlock.Requiresthatthesystemhassomeadditionalaprioriinformationavailable.死锁避免：就是要求操作系统预先提供进程在其生命周期里要请求和释放资源的信息。Logicaladdress:AnaddressgeneratedbytheCPUiscommonlyreferredtoasalogicaladdress.逻辑地址：CPU产生的地址通常称之为逻辑地址Physicaladdress:anaddressseenbythememoryunit–thatis,theoneloadedintothememory-addressregisterofthememory–iscommonlyreferredtoasaphysicaladdress.物理地址：物理地址是内存单元的地址，也就是被装入内存的内存地址寄存器的地址。Dynamiclinking:linkingispostponeduntilexecutiontime.动态链接：动态链接直到进行时才进行链接。Contiguousallocation:Incontiguousmemoryallocation,eachprocessiscontainedinasinglecontiguoussectionofmemory.连续分配：又称连续内存分配，每个进程都包含在一个单独的连续内存区中。Externalfragmentation:Externalfragmentationexistswhenthereisenoughtotalmemoryspacetosatisfyar