中科大操作系统原理与实现课件4_Threads1.pdf

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1、操作系统原理与设计第4章Threads1（线程1）陈香兰中国科学技术大学计算机学院December20,2009......提纲OverviewMultithreadingModelsThreadLibrariesThreadingIssues小结和作业......OutlineOverviewMultithreadingModelsThreadLibrariesThreadingIssues小结和作业......ThreadconceptIIAthreadisabasicunitofCPUutilizationIathreadIDIaprogramcounter

2、IaregistersetIandastackIItshareswithotherthreadsbelongingtothesameprocessIcodesectionIdatasectionIandotherOSresourcesIopenfiles,signals,etc......ThreadconceptIIISinglethreadedVS.Multithreadedprocesses......MotivationIIOnmoderndesktopPC,manyAPPsaremultithreaded.Iaseperateprocess+several

3、threadsIExample1:AwebbrowserIonefordisplayingimagesortext;IanotherforretrievingdatafromnetworkIExample2:AwordprocessorIonefordisplayinggraphics;Ianotherforrespondingtokeystrokesfromtheuser;Iandathirdforperformingspelling&grammercheckinginthebackgroundIMotivation,thinkaboutIawebserver,

4、IanRPCserverIandJava’sRMIsystems......MotivationIIIPARTICULAR,manyOSsystemsarenowmultithreaded.ISolaris,Linux(伪)......Benefits1.Responsiveness(响应度高）IExample:aninteractiveapplicationsuchaswebbrowser,whileonethreadloadinganimage,anotherthreadallowinguserinteraction2.ResourceSharingIaddre

5、ssspace,memory,andotherresources3.EconomyISolaris:creatingaprocessisabout30timesslowerthencreatingathread;contextswitchingisabout5timesslower4.UtilizationofMPArchitecturesIparallelismandconcurrency"......OutlineOverviewMultithreadingModelsThreadLibrariesThreadingIssues小结和作业......TwoMe

6、thodsIITwomethodstosupportthreadsIUserthreadsIKernelthreadsIUserthreadsIThreadmanagementdonebyuser-levelthreadslibrarywithoutkernelsupportIKernelmaybemultithreadedornot.IThreeprimarythreadlibraries:IPOSIXPthreadsIWin32threadsIJavathreads......TwoMethodsIIIKernelThreadsISupportedbytheK

7、ernel,usuallymaybeslowerthenuserthreadIExamplesIWindowsXP/2000ISolarisILinux(伪)ITru64UNIX(formerlyDigitalUNIX)IMacOSX......MultithreadingModelsIITherelationshipbetweenuserthreadsandkernelthreadsIMany-to-OneIOne-to-OneIMany-to-ManyIMany-to-OneIManyuser-levelthreadsmappedtosinglekernelt

8、hread