vm.c

北航操作系统课程设计所需源代码

#include <signal.h>
#include <sys/time.h>
#include <unistd.h>
#include <stdio.h>
#include <sys/types.h>
#include <sys/stat.h>
#include <fcntl.h>

#define FILENAME "/proc/stat"
#define DEFAULTTIME 10          

static void sig_handler(int signo);
int get_page_fault(void);
int readfile(char *data);

int exit_flag=0;
int page_fault;

int main(int argc,char **argv)
{
  struct itimerval v;
  int cacl_time;

  if (signal(SIGALRM,sig_handler)==SIG_ERR)
    {
      printf("Unable to create handler for SIGALRM\n");
      return -1;
    }
  if (argc<=2)
    page_fault=get_page_fault();

  if (argc<2)
    {
      printf("Use default time !\n");
      cacl_time=DEFAULTTIME;
    }
  else if (argc==2) 
    {
      printf("Use user's time\n");
      cacl_time=atoi(argv[1]);
    }
  else if (argc>2)
    {
      printf("Usage :mypage [time]\n");
      return 0;
    }
  v.it_interval.tv_sec=cacl_time;
  v.it_interval.tv_usec=0; 
  //  v.it_value.tv_sec=cacl_time; 
  //  v.it_value.tv_usec=0; 
  setitimer(ITIMER_REAL,&v,NULL);
    
  while(!exit_flag)
    printf("In %d seconds,system calls %d page fault!\n",cacl_time,page_fault);

  return 0;
}

static void sig_handler(int signo)
{
  if (signo==SIGALRM)      
    {
      page_fault=page_fault-get_page_fault();
      exit_flag=1;
    }
}

int get_page_fault(void)
{
  char d[50];
  int retval;

  retval=readfile(d);
  if (retval<0)
    {
      printf("read data from file failed !\n");
      exit(0);
    }
  printf("Now the number of page fault is %s\n",d);
  return atoi(d);
}

/* 
 * return 1 if success 
 * return -1 if failed
 */
int readfile(char *data)
{
  int fd;
  int seekcount=0;
  int retval=0;
  int i=0;
  int count=0;
  char c;
  char string[50];

  fd=open(FILENAME,O_RDONLY);
  if (fd<0)
    {
      printf("Open file /proc/stat failed !\n");
      return -1;
    }
 
  do
    {
      i=0;
      do
	{
	  lseek(fd,seekcount,SEEK_SET);
	  retval=read(fd,&c,sizeof(char));
	  if (retval<0)
	    {
	      printf("read file errr !\n");
	      return retval;
	    }  
	  seekcount+=sizeof(char);
                   
	  if (c==' '||c=='\n')
	    {
	      string[i]=0;
	      break;
	    }     
	  if ((c>='0'&&c<='9')||(c>='a'&&c<='z')||(c>='A'&&c<='Z'))
	    string[i++]=c;

	}while(1);
    }while(strcmp("intr",string));
     
  printf("find intr !\n");


  do
    {
      lseek(fd,seekcount,SEEK_SET);
      retval=read(fd,&c,sizeof(char));
      if (retval<0)
	{
	  printf("read file error !\n");
	  return retval;
	}  
      seekcount+=sizeof(char);
      if (c==' '||c=='\n')
	{
	  string[i]=0;
	  i=0;
	  count++;
	}
      if ((c>='0'&&c<='9')||(c>='a'&&c<='z')||(c>='A'&&c<='Z'))
	string[i++]=c;
    }while(count!=16);
  close(fd);
  strcpy(data,string);
  return 0;
}