proc.c

#include "types.h"
#include "defs.h"
#include "param.h"
#include "memlayout.h"
#include "mmu.h"
#include "x86.h"
#include "proc.h"
#include "spinlock.h"
#include "syscall.h"

int scheduler_algorithm = ROUND_ROBIN;
int process_number;

struct {
  struct spinlock lock;
  struct proc proc[NPROC];
} ptable;

static struct proc *initproc;

int nextpid = 1;
int createdProcess = 1;
extern void forkret(void);
extern void trapret(void);

static void wakeup1(void *chan);

void
pinit(void)
{
  initlock(&ptable.lock, "ptable");
}

// Must be called with interrupts disabled
int
cpuid() {
  return mycpu()-cpus;
}

// Must be called with interrupts disabled to avoid the caller being
// rescheduled between reading lapicid and running through the loop.
struct cpu*
mycpu(void)
{
  int apicid, i;
  
  if(readeflags()&FL_IF)
    panic("mycpu called with interrupts enabled\n");
  
  apicid = lapicid();
  // APIC IDs are not guaranteed to be contiguous. Maybe we should have
  // a reverse map, or reserve a register to store &cpus[i].
  for (i = 0; i < ncpu; ++i) {
    if (cpus[i].apicid == apicid)
      return &cpus[i];
  }
  panic("unknown apicid\n");
}

// Disable interrupts so that we are not rescheduled
// while reading proc from the cpu structure
struct proc*
myproc(void) {
  struct cpu *c;
  struct proc *p;
  pushcli();
  c = mycpu();
  p = c->proc;
  popcli();
  return p;
}

//PAGEBREAK: 32
// Look in the process table for an UNUSED proc.
// If found, change state to EMBRYO and initialize
// state required to run in the kernel.
// Otherwise return 0.
static struct proc*
allocproc(void)
{
  struct proc *p;
  char *sp;

  acquire(&ptable.lock);

  for(p = ptable.proc; p < &ptable.proc[NPROC]; p++)
    if(p->state == UNUSED)
      goto found;

  release(&ptable.lock);
  return 0;

found:
  p->state = EMBRYO;
  p->pid = nextpid++;

  release(&ptable.lock);

  // Allocate kernel stack.
  if((p->kstack = kalloc()) == 0){
    p->state = UNUSED;
    return 0;
  }
  sp = p->kstack + KSTACKSIZE;

  // Leave room for trap frame.
  sp -= sizeof *p->tf;
  p->tf = (struct trapframe*)sp;

  // Set up new context to start executing at forkret,
  // which returns to trapret.
  sp -= 4;
  *(uint*)sp = (uint)trapret;

  sp -= sizeof *p->context;
  p->context = (struct context*)sp;
  memset(p->context, 0, sizeof *p->context);
  p->context->eip = (uint)forkret;
  //for using in FCFS scheduling algorithm
  p->creation_time = ticks + createdProcess++;
  p->process_count = process_number;
  process_number++;
  p->lottery_ticket = 50;
  p->schedQueue = LOTTERY;
  p->filledPointer = 0;
  p->filledId = 0;
  return p;
}

//PAGEBREAK: 32
// Set up first user process.
void
userinit(void)
{
  struct proc *p;
  extern char _binary_initcode_start[], _binary_initcode_size[];

  p = allocproc();
  
  initproc = p;
  if((p->pgdir = setupkvm()) == 0)
    panic("userinit: out of memory?");
  inituvm(p->pgdir, _binary_initcode_start, (int)_binary_initcode_size);
  p->sz = PGSIZE;
  memset(p->tf, 0, sizeof(*p->tf));
  p->tf->cs = (SEG_UCODE << 3) | DPL_USER;
  p->tf->ds = (SEG_UDATA << 3) | DPL_USER;
  p->tf->es = p->tf->ds;
  p->tf->ss = p->tf->ds;
  p->tf->eflags = FL_IF;
  p->tf->esp = PGSIZE;
  p->tf->eip = 0;  // beginning of initcode.S

  safestrcpy(p->name, "initcode", sizeof(p->name));
  p->cwd = namei("/");

  // this assignment to p->state lets other cores
  // run this process. the acquire forces the above
  // writes to be visible, and the lock is also needed
  // because the assignment might not be atomic.
  acquire(&ptable.lock);

  p->state = RUNNABLE;

  release(&ptable.lock);
}

// Grow current process's memory by n bytes.
// Return 0 on success, -1 on failure.
int
growproc(int n)
{
  uint sz;
  struct proc *curproc = myproc();

  sz = curproc->sz;
  if(n > 0){
    if((sz = allocuvm(curproc->pgdir, sz, sz + n)) == 0)
      return -1;
  } else if(n < 0){
    if((sz = deallocuvm(curproc->pgdir, sz, sz + n)) == 0)
      return -1;
  }
  curproc->sz = sz;
  switchuvm(curproc);
  return 0;
}

// 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;
  struct proc *curproc = myproc();
  
  addNewTrace(curproc->pid, SYS_fork, "");

  // Allocate process.
  if((np = allocproc()) == 0){
    return -1;
  }

  // Copy process state from proc.
  if((np->pgdir = copyuvm(curproc->pgdir, curproc->sz)) == 0){
    kfree(np->kstack);
    np->kstack = 0;
    np->state = UNUSED;
    return -1;
  }
  np->sz = curproc->sz;
  np->parent = curproc;
  *np->tf = *curproc->tf;

  // Clear %eax so that fork returns 0 in the child.
  np->tf->eax = 0;

  for(i = 0; i < NOFILE; i++)
    if(curproc->ofile[i])
      np->ofile[i] = filedup(curproc->ofile[i]);
  np->cwd = idup(curproc->cwd);

  safestrcpy(np->name, curproc->name, sizeof(curproc->name));

  pid = np->pid;

  acquire(&ptable.lock);
  np->priority = 1000;
  np->state = RUNNABLE;
  release(&ptable.lock);
  np->count++;
  curproc->count++;

  for(i = 0 ; i < myproc()->filledId ; i++)
  {
    increfcnt(myproc()->id[i]); 
  }
  return pid;
}

// Exit the current process.  Does not return.
// An exited process remains in the zombie state
// until its parent calls wait() to find out it exited.
void
exit(void)
{
  struct proc *curproc = myproc();
  struct proc *p;
  int fd;
  setProcessDead(curproc -> pid);
  addNewTrace(curproc -> pid, SYS_exit, "");
  if(curproc == initproc)
    panic("init exiting");

  // Close all open files.
  for(fd = 0; fd < NOFILE; fd++){
    if(curproc->ofile[fd]){
      fileclose(curproc->ofile[fd]);
      curproc->ofile[fd] = 0;
    }
  }

  begin_op();
  iput(curproc->cwd);
  end_op();
  curproc->cwd = 0;

  acquire(&ptable.lock);

  // Parent might be sleeping in wait().
  wakeup1(curproc->parent);

  // Pass abandoned children to init.
  for(p = ptable.proc; p < &ptable.proc[NPROC]; p++){
    if(p->parent == curproc){
      p->parent = initproc;
      if(p->state == ZOMBIE)
        wakeup1(initproc);
    }
  }
  p->count++;
  curproc->count++;

  // Jump into the scheduler, never to return.
  curproc->state = ZOMBIE;
  sched();
  panic("zombie exit");
}

// Wait for a child process to exit and return its pid.
// Return -1 if this process has no children.
int
wait(void)
{
  struct proc *p;
  int havekids, pid;
  struct proc *curproc = myproc();
  addNewTrace(curproc -> pid, SYS_wait, "");
  acquire(&ptable.lock);
  
  curproc->count++;
  for(;;){
    // Scan through table looking for exited children.
    havekids = 0;
    for(p = ptable.proc; p < &ptable.proc[NPROC]; p++){
      p->count++;
      if(p->parent != curproc)
        continue;
      havekids = 1;
      if(p->state == ZOMBIE){
        // Found one.
        pid = p->pid;
        kfree(p->kstack);
        p->kstack = 0;
        freevm(p->pgdir);
        p->pid = 0;
        p->parent = 0;
        p->name[0] = 0;
        p->killed = 0;
        p->state = UNUSED;
        release(&ptable.lock);
        return pid;
      }
    }

    // No point waiting if we don't have any children.
    if(!havekids || curproc->killed){
      release(&ptable.lock);
      return -1;
    }

    // Wait for children to exit.  (See wakeup1 call in proc_exit.)
    sleep(curproc, &ptable.lock);  //DOC: wait-sleep
  }
}

//Schedulers algorithms 
struct proc*
FCFSSched(void)
{
  struct proc *p;
 
  int earliestProcessSelected = 0;
  struct proc *earliestTime = 0; //process that come earlier
  
  
    earliestProcessSelected = 0;

      for(p = ptable.proc; p < &ptable.proc[NPROC]; p++){
        if(p->state != RUNNABLE || p->schedQueue != FCFS)
          continue;
        if(!earliestProcessSelected){
          earliestTime = p;
          earliestProcessSelected = 1;
        }
        if(earliestTime->creation_time > p->creation_time)
          earliestTime = p;

    }
    if(earliestProcessSelected)
    {
      return earliestTime;
    }
  return 0;
}

//Schedulers algorithms 
void 
roundRobinSched(void)
{
  struct proc *p;
  struct cpu *c = mycpu();
  c->proc = 0;
  
  for(;;){
    // Enable interrupts on this processor.
    sti();

    // Loop over process table looking for process to run.
  acquire(&ptable.lock);
  for(p = ptable.proc; p < &ptable.proc[NPROC]; p++){
    if(p->state != RUNNABLE)
      continue;

    // Switch to chosen process.  It is the process's job
    // to release ptable.lock and then reacquire it
    // before jumping back to us.
    c->proc = p;
    switchuvm(p);
    p->state = RUNNING;

    swtch(&(c->scheduler), p->context);
    switchkvm();

    // Process is done running for now.
    // It should have changed its p->state before coming back.
    c->proc = 0;
  }
  release(&ptable.lock);

  }
}

int generate_random(int toMod)
{
  int random;
  random = (12345678 + ticks*ticks*ticks*ticks) % toMod;
  return random;
}

//Schedulers algorithms 

struct proc*
lotterySched(void){
  struct proc *p;

  int sum_lotteries = 1;
  int random_ticket = 0;
  int isLotterySelected = 0;
  struct proc *highLottery_ticket = 0; //process with highest lottery ticket
  
  sum_lotteries = 1;
  isLotterySelected = 0;
  // Loop over process table looking for process to run.
  for(p = ptable.proc; p < &ptable.proc[NPROC]; p++){
    if(p->state != RUNNABLE || p->schedQueue != LOTTERY)
      continue;
    sum_lotteries += p->lottery_ticket;
  }

  random_ticket = generate_random(sum_lotteries);
  
  for(p = ptable.proc; p < &ptable.proc[NPROC]; p++){
    if(p->state != RUNNABLE || p->schedQueue != LOTTERY)
      continue;
    random_ticket -= p->lottery_ticket;

    if(!isLotterySelected) {
      highLottery_ticket = p;
      isLotterySelected = 1;
      
    }

    if(random_ticket <= 0 && isLotterySelected == 1)
    {
      highLottery_ticket = p;
      isLotterySelected = 2;
    }
  }
   
    if(isLotterySelected != 0) {
      return highLottery_ticket;
    }
    
    
    return 0;

  
}

void find_and_set_priority(int priority , int pid)
{
  struct proc *p;
  for(p = ptable.proc; p < &ptable.proc[NPROC]; p++){
    if(pid == p->pid)
    {
      p -> priority = priority;
      break;
    }
  }
}

void find_and_set_lottery_ticket(int lottery_ticket , int pid){
  struct proc *p;
  for(p = ptable.proc; p < &ptable.proc[NPROC]; p++){
    if(pid == p->pid)
    {
      p -> lottery_ticket = lottery_ticket;
      break;
    }
  }
}

struct proc*
prioritySched(void)
{
  struct proc *p;
  
 
  int priorityProcessSelected = 0;
  struct proc *highPriority = 0; //process with highest priority
  // Enable interrupts on this processor.
  priorityProcessSelected = 0;

  for(p = ptable.proc; p < &ptable.proc[NPROC]; p++){
    if(p->state != RUNNABLE || p->schedQueue != PRIORITY)
      continue;

    if(!priorityProcessSelected)
    {
      highPriority = p;
      priorityProcessSelected = 1;
    }
    if(highPriority->priority > p->priority )
      highPriority = p;
  }
  if(priorityProcessSelected )
  {
    
    return highPriority;
  }
  
  return 0;

}

void 
find_and_set_sched_queue(int qeue_number, int pid)
{
  struct proc *p;
  for(p = ptable.proc; p < &ptable.proc[NPROC]; p++){
    if(pid == p->pid)
    {
      p -> schedQueue = qeue_number;
      break;
    }
  }
}

char* print_state(int state){
  if(state == 0){
    return "UNUSED";
  }else if(state == 1){
    return "EMBRYO";
  }else if(state == 2){
    return "SLEEPING";
  }else if(state == 3){
    return "RUNNABLE";
  }else if(state == 4){
    return "RUNNING";
  }else if(state == 5){
    return "ZOMBIE";
  }else{
    return "";
  }
}

int int_size(int i){
    if( i >= 1000000000) return 10;
    if( i >= 100000000)  return 9;
    if( i >= 10000000)   return 8;
    if( i >= 1000000)    return 7;
    if( i >= 100000)     return 6;
    if( i >= 10000)      return 5;
    if( i >= 1000)       return 4;
    if( i >= 100)        return 3;
    if( i >= 10)         return 2;
                        return 1;
}

char* find_queue_name(int queue){
  if(queue == 1){
    return "PRIORITY";
  }else if(queue == 2){
    return "FCFS";
  }else if(queue == 3){
    return "LOTTERY";
  }else{
    return "";
  }
}

void
show_all_processes_scheduling()
{
  struct proc *p;
  int name_spaces = 0;
  int i = 0 ;
  char* state;
  char* queue_name;
  for(p = ptable.proc; p < &ptable.proc[NPROC]; p++){
    if(p->pid == 0)
      continue;
    if( name_spaces < strlen(p->name))
      name_spaces = strlen(p->name);
  }

  cprintf("name");
  for(i = 0 ; i < name_spaces - strlen("name") + 3 ; i++)
    cprintf(" ");
  
  cprintf("pid");
  for(i = 0 ; i < 4; i++)
    cprintf(" ");
  cprintf("state");
  for(i = 0 ; i < 6; i++)
    cprintf(" ");
  cprintf("queue");
  for(i = 0 ; i < 5; i++)
    cprintf(" ");
  cprintf("priority");
  for(i = 0 ; i < 3; i++)
    cprintf(" ");
  cprintf("lottery");
  for(i = 0 ; i < 3; i++)
    cprintf(" ");
  cprintf("createTime");
  for(i = 0 ; i < 3; i++)
    cprintf(" ");
  cprintf("number\n");
  cprintf("- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - \n");
  for(p = ptable.proc; p < &ptable.proc[NPROC]; p++){
    if(p->pid == 0)
      continue;
    cprintf("%s", p->name);
    for(i = 0 ; i < name_spaces - strlen(p->name) + 4 ; i++)
      cprintf(" ");
    cprintf("%d", p->pid);
    for(i = 0 ; i < 6 - int_size(p->pid); i++)
      cprintf(" ");
    state = print_state(p->state);
    cprintf("%s" , state);
    for(i = 0 ; i < 11 - strlen(state); i++)
      cprintf(" ");
    queue_name =  find_queue_name(p->schedQueue);
    cprintf("%s ", queue_name);
    for(i = 0 ; i < 12 - strlen(queue_name); i++)
      cprintf(" ");
    cprintf("%d  ", p->priority);
    for(i = 0 ; i < 8 - int_size(p->priority); i++)
      cprintf(" ");
    cprintf("%d  ", p->lottery_ticket);
    for(i = 0 ; i < 10 - int_size(p->lottery_ticket); i++)
      cprintf(" ");
    cprintf("%d  ", p->creation_time);
        for(i = 0 ; i < 10 - int_size(p->creation_time); i++)
      cprintf(" ");
    cprintf("%d  " , p->process_count);
    cprintf("\n");
  }
}

//PAGEBREAK: 42
// Per-CPU process scheduler.
// Each CPU calls scheduler() after setting itself up.
// Scheduler never returns.  It loops, doing:
//  - choose a process to run
//  - swtch to start running that process
//  - eventually that process transfers control
//      via swtch back to the scheduler.
void
scheduler(void)
{
  if(scheduler_algorithm == ROUND_ROBIN)
  {
    roundRobinSched();
  }
  else
  {
    struct proc *p;  
    struct cpu *c = mycpu();
    c->proc = 0;
    for(;;){
      // Enable interrupts on this processor.
      sti();
      // Loop over process table looking for process to run.
      acquire(&ptable.lock);
      p = lotterySched();
      
      if(p == 0)
        p = FCFSSched();
      if(p == 0)
        p = prioritySched();
      if(p !=0 ) {
        // Switch to chosen process.  It is the process's job
        // to release ptable.lock and then reacquire it
        // before jumping back to us.
        c->proc = p;
        switchuvm(p);
        p->state = RUNNING;

        swtch(&(c->scheduler), p->context);
        switchkvm();

        // Process is done running for now.
        // It should have changed its p->state before coming back.
        c->proc = 0;
      }

      release(&ptable.lock);
    }
  }
}

// Enter scheduler.  Must hold only ptable.lock
// and have changed proc->state. Saves and restores
// intena because intena is a property of this
// kernel thread, not this CPU. It should
// be proc->intena and proc->ncli, but that would
// break in the few places where a lock is held but
// there's no process.
void
sched(void)
{
  
  int intena;
  struct proc *p = myproc();

  if(!holding(&ptable.lock))
    panic("sched ptable.lock");
  if(mycpu()->ncli != 1)
    panic("sched locks");
  if(p->state == RUNNING)
    panic("sched running");
  if(readeflags()&FL_IF)
    panic("sched interruptible");
  intena = mycpu()->intena;
  swtch(&p->context, mycpu()->scheduler);
  mycpu()->intena = intena;
  

}

// Give up the CPU for one scheduling round.
void
yield(void)
{
  acquire(&ptable.lock);  //DOC: yieldlock
  myproc()->state = RUNNABLE;
  sched();
  release(&ptable.lock);
}

// A fork child's very first scheduling by scheduler()
// will swtch here.  "Return" to user space.
void
forkret(void)
{
  static int first = 1;
  // Still holding ptable.lock from scheduler.
  release(&ptable.lock);

  if (first) {
    // Some initialization functions must be run in the context
    // of a regular process (e.g., they call sleep), and thus cannot
    // be run from main().
    first = 0;
    iinit(ROOTDEV);
    initlog(ROOTDEV);
  }

  // Return to "caller", actually trapret (see allocproc).
}

// Atomically release lock and sleep on chan.
// Reacquires lock when awakened.
void
sleep(void *chan, struct spinlock *lk)
{
  struct proc *p = myproc();
  
  if(p == 0)
    panic("sleep");

  if(lk == 0)
    panic("sleep without lk");

  // Must acquire ptable.lock in order to
  // change p->state and then call sched.
  // Once we hold ptable.lock, we can be
  // guaranteed that we won't miss any wakeup
  // (wakeup runs with ptable.lock locked),
  // so it's okay to release lk.
  if(lk != &ptable.lock){  //DOC: sleeplock0
    acquire(&ptable.lock);  //DOC: sleeplock1
    release(lk);
  }
  // Go to sleep.
  p->chan = chan;
  p->state = SLEEPING;

  sched();

  // Tidy up.
  p->chan = 0;

  // Reacquire original lock.
  if(lk != &ptable.lock){  //DOC: sleeplock2
    release(&ptable.lock);
    acquire(lk);
  }
}

void
ticketSleep(struct ticketlock *chan)
{
  struct proc *p = myproc();
  if(p == 0)
    panic("sleep");
  
  acquire(&ptable.lock);  
  p->chan = chan;
  p->state = SLEEPING;
  sched();
  p->chan = 0;
  release(&ptable.lock);
}


//PAGEBREAK!
// Wake up all processes sleeping on chan.
// The ptable lock must be held.
static void
wakeup1(void *chan)
{
  struct proc *p;

  for(p = ptable.proc; p < &ptable.proc[NPROC]; p++)
    if(p->state == SLEEPING && p->chan == chan)
      p->state = RUNNABLE;
}

// Wake up all processes sleeping on chan.
void
wakeup(void *chan)
{
  acquire(&ptable.lock);
  wakeup1(chan);
  release(&ptable.lock);
}

// Kill the process with the given pid.
// Process won't exit until it returns
// to user space (see trap in trap.c).
int
kill(int pid)
{
  struct proc *p;
  struct proc *curproc = myproc();
  curproc->count++;

  char argsForTrace[256]; strncpy(argsForTrace, " ", 2);
  char temp[128];
  addNewArgTrace(argsForTrace, itoa_simple(temp, pid), "int");
  addNewTrace(curproc -> pid, SYS_kill,argsForTrace);

  acquire(&ptable.lock);
  for(p = ptable.proc; p < &ptable.proc[NPROC]; p++){
    p->count++;
    if(p->pid == pid){
      p->killed = 1;
      // Wake process from sleep if necessary.
      if(p->state == SLEEPING)
        p->state = RUNNABLE;
      release(&ptable.lock);
      return 0;
    }
  }
  release(&ptable.lock);
  return -1;
}

//PAGEBREAK: 36
// Print a process listing to console.  For debugging.
// Runs when user types ^P on console.
// No lock to avoid wedging a stuck machine further.
void
procdump(void)
{
  static char *states[] = {
  [UNUSED]    "unused",
  [EMBRYO]    "embryo",
  [SLEEPING]  "sleep ",
  [RUNNABLE]  "runble",
  [RUNNING]   "run   ",
  [ZOMBIE]    "zombie"
  };
  int i;
  struct proc *p;
  char *state;
  uint pc[10];

  for( p= ptable.proc; p < &ptable.proc[NPROC]; p++){
    if(p->state == UNUSED)
      continue;
    if(p->state >= 0 && p->state < NELEM(states) && states[p->state])
      state = states[p->state];
    else
      state = "???";
    cprintf("%d %s %s", p->pid, state, p->name);
    if(p->state == SLEEPING){
      getcallerpcs((uint*)p->context->ebp+2, pc);
      for(i=0; i<10 && pc[i] != 0; i++)
        cprintf(" %p", pc[i]);
    }
    cprintf(" system call count: %d" , p->count);
    cprintf("\n");
  }
}