《2.4Linux的进程管理.docVIP

Linux的进程管理 Linux中的每一个进程用一个task_struct数据结构来表示，所有指向这些数据结构的指针构成进程的向量数组task，系统的进程向量数组大小是512，系统中最多能容纳512个进程（Linux2.4及以后内核无此限制）。当新的进程创建的时候，从系统内存中分配一个新的task_struct结构，并加到task数组中。当前进程指针current指向当前运行的进程。task_struct的结构描述在/include/linux/seched.h文件中。 Linux的进程控制块task_struct及进程状态 1．Linux的进程控制块task_struct 在Linux中进程称为任务，进程控制块是task_struct结构，它在include/linux/sched.h中定义并解释。 struct task_struct { /* these are hardcoded - dont touch */ volatile long state; /* -1 unrunnable, 0 runnable, 0 stopped */ long counter; long priority; unsigned long signal; unsigned long blocked; /* bitmap of masked signals */ unsigned long flags; /* per process flags, defined below */ int errno; long debugreg[8]; /* Hardware debugging registers */ struct exec_domain *exec_domain; /* various fields */ struct linux_binfmt *binfmt; struct task_struct *next_task, *prev_task; struct task_struct *next_run, *prev_run; unsigned long saved_kernel_stack; unsigned long kernel_stack_page; int exit_code, exit_signal; /* ??? */ unsigned long personality; int dumpable:1; int did_exec:1; int pid; int pgrp; int tty_old_pgrp; int session; /* boolean value for session group leader */ int leader; int groups[NGROUPS]; /* * pointers to (original) parent process, youngest child, younger sibling, * older sibling, respectively. (p-father can be replaced with Linux Kernel Page 147 * p-p_pptr-pid) */ struct task_struct *p_opptr, *p_pptr, *p_cptr, *p_ysptr, *p_osptr; struct wait_queue *wait_chldexit; unsigned short uid,euid,suid,fsuid; unsigned short gid,egid,sgid,fsgid; unsigned long timeout, policy, rt_priority; unsigned long it_real_value, it_prof_value, it_virt_value; unsigned long it_real_incr, it_prof_incr, it_virt_incr; struct timer_list real_timer; long utime, stime, cutime, cstime, start_time; /* mm fault and swap info: this can arguably be seen as either mm-specific or thread-specific */ unsigned long min_flt, maj_flt, nswap, cmin_flt, cmaj_flt, cnswap; int swappable:1; unsigned long swap_address; unsigned long old_maj_flt; /*