sched.c sched.h 代码分析笔记

首先上header file

sched.h

#ifndef _SCHED_H
#define _SCHED_H

#define HZ 100

#define NR_TASKS    64
#define TASK_SIZE    0x04000000
#define LIBRARY_SIZE    0x00400000

#if (TASK_SIZE & 0x3fffff)
#error "TASK_SIZE must be multiple of 4M"
#endif

#if (LIBRARY_SIZE & 0x3fffff)
#error "LIBRARY_SIZE must be a multiple of 4M"
#endif

#if (LIBRARY_SIZE >= (TASK_SIZE/2))
#error "LIBRARY_SIZE too damn big!"
#endif

#if (((TASK_SIZE>>16)*NR_TASKS) != 0x10000)
#error "TASK_SIZE*NR_TASKS must be 4GB"
#endif

#define LIBRARY_OFFSET (TASK_SIZE - LIBRARY_SIZE)

#define CT_TO_SECS(x)    ((x) / HZ)
#define CT_TO_USECS(x)    (((x) % HZ) * 1000000/HZ)

#define FIRST_TASK task[0]
#define LAST_TASK task[NR_TASKS-1]

#include <linux/head.h>
#include <linux/fs.h>
#include <linux/mm.h>
#include <sys/param.h>
#include <sys/time.h>
#include <sys/resource.h>
#include <signal.h>

#if (NR_OPEN > 32)
#error "Currently the close-on-exec-flags and select masks are in one long, max 32 files/proc"
#endif

#define TASK_RUNNING        0
#define TASK_INTERRUPTIBLE    1
#define TASK_UNINTERRUPTIBLE    2
#define TASK_ZOMBIE        3
#define TASK_STOPPED        4

#ifndef NULL
#define NULL ((void *) 0)
#endif

extern int copy_page_tables(unsigned long from, unsigned long to, long size);
extern int free_page_tables(unsigned long from, unsigned long size);

extern void sched_init(void);
extern void schedule(void);
extern void trap_init(void);
extern void panic(const char * str);
extern int tty_write(unsigned minor,char * buf,int count);

typedef int (*fn_ptr)();

struct i387_struct {
    long    cwd;
    long    swd;
    long    twd;
    long    fip;
    long    fcs;
    long    foo;
    long    fos;
    long    st_space[20];    /* 8*10 bytes for each FP-reg = 80 bytes */
};

struct tss_struct {
    long    back_link;    /* 16 high bits zero */
    long    esp0;
    long    ss0;        /* 16 high bits zero */
    long    esp1;
    long    ss1;        /* 16 high bits zero */
    long    esp2;
    long    ss2;        /* 16 high bits zero */
    long    cr3;
    long    eip;
    long    eflags;
    long    eax,ecx,edx,ebx;
    long    esp;
    long    ebp;
    long    esi;
    long    edi;
    long    es;        /* 16 high bits zero */
    long    cs;        /* 16 high bits zero */
    long    ss;        /* 16 high bits zero */
    long    ds;        /* 16 high bits zero */
    long    fs;        /* 16 high bits zero */
    long    gs;        /* 16 high bits zero */
    long    ldt;        /* 16 high bits zero */
    long    trace_bitmap;    /* bits: trace 0, bitmap 16-31 */
    struct i387_struct i387;
};

struct task_struct {
/* these are hardcoded - don't touch */
    long state;    /* -1 unrunnable, 0 runnable, >0 stopped */
    long counter;
    long priority;
    long signal;
    struct sigaction sigaction[32];
    long blocked;    /* bitmap of masked signals */
/* various fields */
    int exit_code;
    unsigned long start_code,end_code,end_data,brk,start_stack;
    long pid,pgrp,session,leader;
    int    groups[NGROUPS];
    /*
     * pointers to parent process, youngest child, younger sibling,
     * older sibling, respectively.  (p->father can be replaced with
     * p->p_pptr->pid)
     */
    struct task_struct    *p_pptr, *p_cptr, *p_ysptr, *p_osptr;
    unsigned short uid,euid,suid;
    unsigned short gid,egid,sgid;
    unsigned long timeout,alarm;
    long utime,stime,cutime,cstime,start_time;
    struct rlimit rlim[RLIM_NLIMITS];
    unsigned int flags;    /* per process flags, defined below */
    unsigned short use