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proc.c
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proc.c
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#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 <stddef.h>
struct {
struct spinlock lock;
struct proc proc[NPROC];
} ptable;
static struct proc *initproc;
int nextpid = 1;
int schedPolicy = 0;
extern void forkret(void);
extern void trapret(void);
static void wakeup1(void *chan);
struct spinlock threadLock; //lock for growing address space
int random_at_most(int max);
int lottery_Total(void);
void
pinit(void)
{
initlock(&ptable.lock, "ptable");
initlock(&threadLock, "threadLock"); //read the details!
}
// 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++;
p->stackTop = -1;
p->threads = -1;
p->ctime = ticks;
p->retime = 0;
p->rutime = 0;
p->stime = 0;
p->priority = 3; //default value of priority
p->qua = 0;
p->tickets = 10;
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;
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;
// ####
p->ctime = ticks;
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();
acquire(&threadLock); //lock the threadLock
sz = curproc->sz;
if(n > 0){
if((sz = allocuvm(curproc->pgdir, sz, sz + n)) == 0){
release(&threadLock);
return -1;
}
} else if(n < 0){
if((sz = deallocuvm(curproc->pgdir, sz, sz + n)) == 0){
release(&threadLock);
return -1;
}
}
curproc->sz = sz; //update the size of current process
acquire(&ptable.lock);
//we want to update sz in all threads
struct proc *p;
int numberOfChildren;
if(curproc->threads == -1){ //child thread
//we have to update parent and sibilings
curproc->parent->sz = curproc->sz; //update parent sz
numberOfChildren = curproc->parent->threads - 2; //number or its sibilings
if(numberOfChildren <= 0){
//doesn't have sibilings
release(&ptable.lock);
release(&threadLock);
switchuvm(curproc);
return 0;
}
else{
//have sibilings
for(p = ptable.proc; p < &ptable.proc[NPROC]; p++){
if(p != curproc && p->parent == curproc->parent && p->threads == -1){
p->sz = curproc->sz;
numberOfChildren--;
}
}
}
}
else{
//parent
numberOfChildren = curproc->threads - 1;
if(numberOfChildren <= 0){
//have no children
release(&ptable.lock);
release(&threadLock);
switchuvm(curproc);
return 0;
}
else{
//have chilren which we should update there size
for(p = ptable.proc; p < &ptable.proc[NPROC]; p++){
if(p->parent == curproc && p->threads == -1){
p->sz = curproc->sz;
numberOfChildren--;
}
}
}
}
release(&ptable.lock);
release(&threadLock);
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();
// 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->threads = 1; //the new process is a child process.
*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->state = RUNNABLE;
release(&ptable.lock);
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;
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);
}
}
// Jump into the scheduler, never to return.
curproc->state = ZOMBIE;
// ####
curproc->ttime = ticks;
sched();
panic("zombie exit");
}
int
check_pgdir_share(struct proc *process){
struct proc *p;
for(p = ptable.proc; p < &ptable.proc[NPROC]; p++){
if(p != process && p->pgdir == process->pgdir)
return 0; //there is still a thread with the same pgdir
}
return 1; //it's okay to free pgdir
}
// 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();
acquire(&ptable.lock);
for(;;){
// Scan through table looking for exited children.
havekids = 0;
for(p = ptable.proc; p < &ptable.proc[NPROC]; p++){
if(p->parent != curproc)
continue;
if(p->threads == -1)
continue; //it is a child thread! not a process!
havekids = 1;
if(p->state == ZOMBIE){
// Found one.
pid = p->pid;
kfree(p->kstack);
p->kstack = 0;
if(check_pgdir_share(p)) //there is still threads running
freevm(p->pgdir);
p->pid = 0;
p->parent = 0;
p->name[0] = 0;
p->killed = 0;
p->state = UNUSED;
//reset stackTop and pgdir
p->stackTop = -1;
p->pgdir = 0;
p->threads = -1;
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
}
}
int wait2(int *retime, int *rutime, int *stime) {
struct proc *p;
int havekids, pid;
acquire(&ptable.lock);
for(;;){
// Scan through table looking for zombie children.
havekids = 0;
for(p = ptable.proc; p < &ptable.proc[NPROC]; p++){
if(p->parent != myproc())
continue;
havekids = 1;
if(p->state == ZOMBIE){
// Found one.
*retime = p->retime;
*rutime = p->rutime;
*stime = p->stime;
pid = p->pid;
kfree(p->kstack);
p->kstack = 0;
freevm(p->pgdir);
p->state = UNUSED;
p->pid = 0;
p->parent = 0;
p->name[0] = 0;
p->killed = 0;
p->ctime = 0;
p->retime = 0;
p->rutime = 0;
p->stime = 0;
p->priority = 0;
release(&ptable.lock);
return pid;
}
}
// No point waiting if we don't have any children.
if(!havekids || myproc()->killed){
release(&ptable.lock);
return -1;
}
// Wait for children to exit. (See wakeup1 call in proc_exit.)
sleep(myproc(), &ptable.lock); //DOC: wait-sleep
}
}
struct proc* findReadyProcess(int *index1, int *index2, int *index3, int *index4, int *index5, int *index6,uint *priority) {
int i;
struct proc* proc2;
notfound:
for (i = 0; i < NPROC; i++) {
switch(*priority) {
case 1:
proc2 = &ptable.proc[(*index1 + i) % NPROC];
if (proc2->state == RUNNABLE && proc2->priority == *priority) {
*index1 = (*index1 + 1 + i) % NPROC;
proc2->qua=6;
return proc2; // found a runnable process with appropriate priority
}
case 2:
proc2 = &ptable.proc[(*index2 + i) % NPROC];
if (proc2->state == RUNNABLE && proc2->priority == *priority) {
*index2 = (*index2 + 1 + i) % NPROC;
proc2->qua=5;
return proc2; // found a runnable process with appropriate priority
}
case 3:
proc2 = &ptable.proc[(*index3 + i) % NPROC];
if (proc2->state == RUNNABLE && proc2->priority == *priority){
*index3 = (*index3 + 1 + i) % NPROC;
proc2->qua=4;
return proc2; // found a runnable process with appropriate priority
}
case 4:
proc2 = &ptable.proc[(*index1 + i) % NPROC];
if (proc2->state == RUNNABLE && proc2->priority == *priority) {
*index4 = (*index4 + 1 + i) % NPROC;
proc2->qua=3;
return proc2; // found a runnable process with appropriate priority
}
case 5:
proc2 = &ptable.proc[(*index1 + i) % NPROC];
if (proc2->state == RUNNABLE && proc2->priority == *priority) {
*index5 = (*index5 + 1 + i) % NPROC;
proc2->qua=2;
return proc2; // found a runnable process with appropriate priority
}
case 6:
proc2 = &ptable.proc[(*index1 + i) % NPROC];
if (proc2->state == RUNNABLE && proc2->priority == *priority) {
*index6 = (*index6 + 1 + i) % NPROC;
proc2->qua=1;
return proc2; // found a runnable process with appropriate priority
}
}
}
if (*priority == 6) {//did not find any process on any of the prorities
*priority = 6;
return 0;
}
else {
*priority += 1; //will try to find a process at a lower priority (ighter value of priority)
goto notfound;
}
return 0;
}
//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)
{
struct proc *p;
struct cpu *c = mycpu();
c->proc = 0;
int count = 0;
long golden_ticket = 0;
int total_no_tickets = 0;
for(;;){
// Enable interrupts on this processor.
sti();
acquire(&ptable.lock);
//resetting the variables to make scheduler start from the beginning of the process queue
golden_ticket = 0;
count = 0;
total_no_tickets = 0;
//calculate Total number of tickets for runnable processes
total_no_tickets = lottery_Total();
//pick a random ticket from total available tickets
golden_ticket = random_at_most(total_no_tickets);
// Loop over process table looking for process to run.
for(p = ptable.proc; p < &ptable.proc[NPROC]; p++){
if(schedPolicy == 0){
if(p->state != RUNNABLE)
continue;
}
if(schedPolicy == 1){
struct proc *highP = 0;
struct proc *p1 = 0;
if(p->state != RUNNABLE)
continue;
// Choose the process with highest priority (among RUNNABLEs)
highP = p;
for(p1 = ptable.proc; p1 < &ptable.proc[NPROC]; p1++){
if((p1->state == RUNNABLE) && (highP->priority > p1->priority))
highP = p1;
}
if(highP != 0)
p = highP;
}
if(schedPolicy == 2){ //Multi level
struct proc *foundP = 0;
uint priority = 1;
int index1 = 0;
int index2 = 0;
int index3 = 0;
int index4 = 0;
int index5 = 0;
int index6 = 0;
foundP = findReadyProcess(&index1, &index2, &index3,&index4, &index5, &index6, &priority);
if (foundP != 0)
p = foundP;
else{
if(p->state != RUNNABLE)
continue;
}
}
if(schedPolicy == 3){ //Lottery
if(p->state != RUNNABLE)
continue;
//find the process which holds the lottery winning ticket
if ((count + p->tickets) < golden_ticket){
count += p->tickets;
continue;
}
}
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);
}
}
//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;
acquire(&ptable.lock);
for(p = ptable.proc; p < &ptable.proc[NPROC]; p++){
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("\n");
}
}
int
getTicks(void){
cprintf("%d\n", ticks);
return 0;
}
int
getProcInfo(void){
struct proc *p;
for(p = ptable.proc; p < &ptable.proc[NPROC]; p++){
if(p->state == RUNNING){
cprintf("#pid = %d, create time = %d\n", p->pid, p->ctime);
}
// if(p->state == SLEEPING){
// cprintf("-pid = %d, create time = %d\n", p->pid, p->ctime);
// }
}
return 0;
}
int
thread_create(void *stack)
{
int i, pid;
struct proc *np; //new process
struct proc *curproc = myproc();
// Allocate process.
if((np = allocproc()) == 0){
return -1;
}
//incerase thread numbers for parent (default for child is -1)
curproc->threads++;
//grow downwards
np->stackTop = (int)((char*)stack + PGSIZE);
acquire(&ptable.lock);
np->pgdir = curproc->pgdir; //page directory
np->sz = curproc->sz; //size of thread
release(&ptable.lock);
int bytesOnStack = curproc->stackTop - curproc->tf->esp;
np->tf->esp = np->stackTop - bytesOnStack;
memmove((void*)np->tf->esp, (void*)curproc->tf->esp, bytesOnStack);
np->parent = curproc;
// copy all trap frame register values from p into newp
*np->tf = *curproc->tf;
// Clear %eax so that fork returns 0 in the child because we had copied all parent data in child and fork return value for parent was child PID
np->tf->eax = 0;
// esp is stack pointer (update it to grow down on the size of bytes)
np->tf->esp = np->stackTop - bytesOnStack;
// ebp is the base pointer
np->tf->ebp = np->stackTop - (curproc->stackTop - curproc->tf->ebp);
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->state = RUNNABLE;
release(&ptable.lock);
return pid;
}
int
thread_join(int input_pid)
{
acquire(&threadLock);
int flag = 0;
struct proc *p;
// search for thread
for(p = ptable.proc; p < &ptable.proc[NPROC]; p++){
if((p->pid) == input_pid){
flag = 1;
break;
}
}
release(&threadLock);
if(flag == 0)
return -1;
acquire(&ptable.lock);
for(;;){
if(p->state == ZOMBIE){
// Found one.
kfree(p->kstack);
p->kstack = 0;
if(check_pgdir_share(p)){ //check if there are still some threads left with this pagedir
freevm(p->pgdir);
}
p->pid = 0;
p->parent = 0;
p->name[0] = 0;
p->killed = 0;
p->state = UNUSED;
p->stackTop = 0;
p->pgdir = 0;
p->threads = -1;
release(&ptable.lock);
return 0;
}
// No point waiting if we don't have any children.
if(p->killed){
release(&ptable.lock);
return -1;
}
// Wait for children to exit. (See wakeup1 call in proc_exit.)
sleep(p->parent, &ptable.lock); //DOC: wait-sleep
}
}
int
thread_id(void)
{
struct proc *curproc = myproc();
return curproc->pid;
}
void updateStatus() {
struct proc *p;
acquire(&ptable.lock);
for(p = ptable.proc; p < &ptable.proc[NPROC]; p++){
switch(p->state) {
case RUNNABLE:
p->retime++;
break;
case SLEEPING:
p->stime++;
break;
case RUNNING:
p->rutime++;
break;
default:
;
}
}
release(&ptable.lock);
}
int
setPriority(int priority, int pid){
struct proc *p;
if(priority<1 || priority>6){
priority = 5;
}
acquire(&ptable.lock);
for(p = ptable.proc; p < &ptable.proc[NPROC]; p++){
if(p->pid == pid){
p->priority = priority;
}
}
release(&ptable.lock);
return 0;
}
int
getPriority(int pid){
struct proc *p;
acquire(&ptable.lock);
for(p = ptable.proc; p < &ptable.proc[NPROC]; p++){
if(p->pid == pid){
// cprintf("priority for %d is %d\n", pid, p->priority);
return p->priority;
}
}
release(&ptable.lock);
return 0;
}
uint
getctime(int pid){
struct proc *p;
acquire(&ptable.lock);
for(p = ptable.proc; p < &ptable.proc[NPROC]; p++){
if(p->pid == pid){
return p->ctime;
}
}
release(&ptable.lock);
return 0;
}
int
getttime(int pid){
struct proc *p;
acquire(&ptable.lock);
for(p = ptable.proc; p < &ptable.proc[NPROC]; p++){
if(p->pid == pid){