中科大操作系统原理与实现课件4_Threads2.pdf

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1、.操作系统原理与设计第4章 Threads2（线程2）陈香兰中国科学技术大学计算机学院December 20,2009.提纲OS Examples for ThreadThread SchedulingOS Examples for Thread Scheduling小结和作业.OutlineOS Examples for ThreadThread SchedulingOS Examples for Thread Scheduling小结和作业.Windows XP Threads IIAn Windows XP application runs as a seperate process,a

2、ndeach process may contain one or more threads.IImplements the one-to-one mappingIeach user-level thread maps to an assotiated kernel threadIany thread belonging to a process can access the address spaceof the processIEach thread containsIA thread idIRegister setISeparate user and kernel stacksIPriv

3、ate data storage areaIThe register set,stacks,and private storage area are known asthe context of the threads.Windows XP Threads IIIThe primary data structures of a thread include:IETHREAD(executive thread block)IKTHREAD(kernel thread block)ITEB(thread environment block).Windows XP Threads III.Linux

4、 ThreadsILinux refers to them as tasks rather than threadsIThread creation is done through clone()system callIclone()allows a child task to share the address space ofthe parent task(process)Iclone()VS.fork().Java ThreadsIJava在语言级提供线程创建和管理支持功能IJava threads are managed by the JVM,not user-level librar

5、y orkernelIJava threads may be created by:IExtending Thread classIImplementing the Runnable interface Java.Thread States.OutlineOS Examples for ThreadThread SchedulingOS Examples for Thread Scheduling小结和作业.Thread SchedulingIuser-level thread:kernel-level thread(or LWP)ILocal Scheduling How the threa

6、ds library decides whichthread to put onto an available LWPImany-to-one,many-to-many modelsIprocess-contention scope,PCSIGlobal Scheduling How the kernel decides which kernelthread to run nextImany-to-one,many-to-many&one-to-one modelsIsystem-contention scope,SCS.Pthread Scheduling API IIPOSIX Pthre

7、ad API allows specifying either PCS or SCSduring thread creationIPTHREAD SCOPE PROCESS,many-to-manyIPTHREAD SCOPE SYSTEM,one-to-oneIcreate and bind an LWP for each user-level threadIexample#include#include#define NUM THREADS 5int main(int argc,char*argv)int i;pthread t tidNUM THREADS;pthread attr t

8、attr;pthread attr init(&attr);/*get the default attributes*/.Pthread Scheduling API II/*set the scheduling algorithm to PROCESS or SYSTEM*/pthread attr setscope(&attr,PTHREAD SCOPE SYSTEM);/*set the scheduling policy-FIFO,RT,or OTHER*/pthread attr setschedpolicy(&attr,SCHED OTHER);for(i=0;i NUM THRE

9、ADS;i+)/*create the threads*/pthread create(&tidi,&attr,runner,NULL);for(i=0;i NUM THREADS;i+)/*now join on each thread*/pthread join(tidi,NULL);/*Each thread will begin control in this function*/void*runner(void*param)printf(“I am a threadn”);pthread exit(0);.Solaris scheduling IISolaris:priority-b

10、ased thread schedulingI4 classes of scheduling,in order of priorityIReal timeISystem(do not change the priority)ITime sharing(default,with a multilevel feedback queue)IInteractive,the same as time sharing,but higher priorityIWithin each class there are different priorities and differentscheduling al

11、gorithms.Solaris scheduling II.Solaris scheduling IIIISolaris Dispatch Table.Windows XP schedulingIDispatcher:priority-based,preemptive scheduling algorithmIthe dispatcher uses a-32 level priority scheme to determine theorder of thread executionI0:idle threadI115:variable classes prioritiesI1631:rea

12、l-time classIa queue for each priorityIWindows XP Priorities(policy classes,relative priority).OutlineOS Examples for ThreadThread SchedulingOS Examples for Thread Scheduling小结和作业.小结OS Examples for ThreadThread SchedulingOS Examples for Thread Scheduling小结和作业.作业I非华夏班：5.1,5.3I华夏班：4.4,4.7.上机作业I所有：I写一个多线程的程序，求素数。I要求1：用户运行程序时在命令行输入一个素数，然后程序创建一个独立新的线程来输出小于或等于用户所输入数的所有素数。I要求2：采用两种thread来实现Ipthread或者Windows thread或者Java thread谢谢！