// Create a new process copying p as the parent.
// Sets up stack to return as if from system call.
// Caller must set state of returned proc to RUNNABLE.
int
fork(void)
{
int i, pid;
struct proc *np;
// Allocate process.
if((np = allocproc()) == 0)
return -1;
// Copy process state from p.
if((np->pgdir = copyuvm(proc->pgdir, proc->sz)) == 0){
kfree(np->kstack);
np->kstack = 0;
np->state = UNUSED;
return -1;
}
np->sz = proc->sz;
np->parent = proc;
*np->tf = *proc->tf;
// Clear %eax so that fork returns 0 in the child.
np->tf->eax = 0;
for(i = 0; i < NOFILE; i++)
if(proc->ofile[i])
np->ofile[i] = filedup(proc->ofile[i]);
np->cwd = idup(proc->cwd);
pid = np->pid;
np->state = RUNNABLE;
safestrcpy(np->name, proc->name, sizeof(proc->name));
//cprintf("#");
if(np->pid > 3){
wakeup2(inswapper);
}
return pid;
}
int main(int argc,char** argv)
{
int pid;
printf(1,"\n**************** PART 1 *****************\n\n");
printf(1,"Enabling swapping now...\n");
enableSwapping();
if((pid = fork())==0)
{
pid = getpid();
printf(1,"Child process Pid = %d has %d memory pages allocated, going to sleep and will be swapped out\n",pid,getAllocatedPages(pid));
sleep2();
printf(1,"Child process pid = %d has woken up and was swapped in - has %d memory pages allocated.\n",pid,getAllocatedPages(pid));
exit();
}
else
{
int j,k;
for(j=0;j<10000000;j++)
{
k = j;
j = j+1;
j = k;
}
if(fork()==0)
{
printf(1,"we will now run the 'ls' command and see that the %d.swap file is created\n",pid);
exec("ls",argv);
}
else
{
for(j=0;j<10000000;j++)
{
k = j;
j = j+1;
j = k;
}
printf(1,"\nChild process Pid = %d is sleeping and swapped out - has %d memory pages allocated.\n",pid,getAllocatedPages(pid));
wakeup2();
while(wait()>0);
printf(1,"\n\n**************** PART 2 *****************\n\n");
printf(1,"Disabling swapping now...\n");
disableSwapping();
if((pid = fork())==0)
{
pid = getpid();
printf(1,"Child process Pid = %d has %d memory pages allocated, going to sleep and WILL NOT be swapped out\n",pid,getAllocatedPages(pid));
sleep2();
printf(1,"Child process pid = %d has woken up and was swapped in - has %d memory pages allocated.\n",pid,getAllocatedPages(pid));
exit();
}
else
{
if(fork()==0)
{
printf(1,"we will now run the 'ls' command and see that the %d.swap file has not been created\n",pid);
exec("ls",argv);
}
else
{
sleep(100);
printf(1,"\nChild process Pid = %d is sleeping and NOT swapped out - has %d memory pages allocated.\n",pid,getAllocatedPages(pid));
wakeup2();
}
}
}
}
while(wait()>0);
exit();
}