//----------------------------------------------------------------------
//
// ProcessSchedule
//
// Schedule the next process to run. If there are no processes to
// run, exit. This means that there should be an idle loop process
// if you want to allow the system to "run" when there's no real
// work to be done.
//
// NOTE: the scheduler should only be called from a trap or interrupt
// handler. This way, interrupts are disabled. Also, it must be
// called consistently, and because it might be called from an interrupt
// handler (the timer interrupt), it must ALWAYS be called from a trap
// or interrupt handler.
//
// Note that this procedure doesn't actually START the next process.
// It only changes the currentPCB and other variables so the next
// return from interrupt will restore a different context from that
// which was saved.
//
//----------------------------------------------------------------------
void
ProcessSchedule ()
{
PCB *pcb;
int i;
dbprintf ('p', "Now entering ProcessSchedule (cur=0x%x, %d ready)\n",
currentPCB, QueueLength (&runQueue));
// The OS exits if there's no runnable process. This is a feature, not a
// bug. An easy solution to allowing no runnable "user" processes is to
// have an "idle" process that's simply an infinite loop.
if (QueueEmpty (&runQueue)) {
printf ("No runnable processes - exiting!\n");
exitsim (); // NEVER RETURNS
}
// Move the front of the queue to the end, if it is the running process.
pcb = (PCB *)((QueueFirst (&runQueue))->object);
if (pcb == currentPCB)
{
QueueRemove (&pcb->l);
QueueInsertLast (&runQueue, &pcb->l);
}
// Now, run the one at the head of the queue.
pcb = (PCB *)((QueueFirst (&runQueue))->object);
currentPCB = pcb;
dbprintf ('p',"About to switch to PCB 0x%x,flags=0x%x @ 0x%x\n",
pcb, pcb->flags,
pcb->sysStackPtr[PROCESS_STACK_IAR]);
// Clean up zombie processes here. This is done at interrupt time
// because it can't be done while the process might still be running
while (!QueueEmpty (&zombieQueue)) {
pcb = (PCB *)(QueueFirst (&zombieQueue)->object);
dbprintf ('p', "Freeing zombie PCB 0x%x.\n", pcb);
QueueRemove (&pcb->l);
ProcessFreeResources (pcb);
}
// Set the timer so this process gets at most a fixed quantum of time.
TimerSet (processQuantum);
dbprintf ('p', "Leaving ProcessSchedule (cur=0x%x)\n", currentPCB);
}
PCB *
ProcessHighestPriority() {
PCB *ret = NULL;
int i;
for (i = 0; i < 32; i++) {
if ((&runQueue[i])->nitems != 0) {
dbprintf('p', "Found process to run in queue [%i]\n",i);
ret = (PCB *)(QueueFirst(&runQueue[i])->object);
break;
}
}
return ret;
}
//----------------------------------------------------------------------
//
// SemSignal
//
// Signal on a semaphore. Again, details are in Section 6.4 of
// _OSC_.
//
//----------------------------------------------------------------------
void
SemSignal (Sem *sem)
{
Link *l;
int intrs;
intrs = DisableIntrs ();
dbprintf ('s', "Signalling on sem 0x%x, count=%d.\n", sem, sem->count);
sem->count += 1;
if (sem->count <= 0) {
l = QueueFirst (&sem->waiting);
QueueRemove (l);
dbprintf ('s', "Waking up PCB 0x%x.\n", l->object);
ProcessWakeup ((PCB *)(l->object));
QueueFreeLink (l);
}
RestoreIntrs (intrs);
}
//----------------------------------------------------------------------
//
// ProcessFork
//
// Create a new process and make it runnable. This involves the
// following steps:
// * Allocate resources for the process (PCB, memory, etc.)
// * Initialize the resources
// * Place the PCB on the runnable queue
//
// NOTE: This code has been tested for system processes, but not
// for user processes.
//
//----------------------------------------------------------------------
int
ProcessFork (VoidFunc func, uint32 param, int p_nice, int p_info,char *name, int isUser)
{
int i, j, fd, n;
Link *l;
int start, codeS, codeL, dataS, dataL;
uint32 *stackframe;
int newPage;
PCB *pcb;
int addr = 0;
int intrs;
unsigned char buf[100];
uint32 dum[MAX_ARGS+8], count, offset;
char *str;
intrs = DisableIntrs ();
dbprintf ('I', "Old interrupt value was 0x%x.\n", intrs);
dbprintf ('p', "Entering ProcessFork args=0x%x 0x%x %s %d\n", func,
param, name, isUser);
// Get a free PCB for the new process
if (QueueEmpty (&freepcbs)) {
printf ("FATAL error: no free processes!\n");
exitsim (); // NEVER RETURNS!
}
l = QueueFirst (&freepcbs);
dbprintf ('p', "Got a link @ 0x%x\n", l);
QueueRemove (l);
pcb = (PCB *)(l->object);
// This prevents someone else from grabbing this process
ProcessSetStatus (pcb, PROCESS_STATUS_RUNNABLE);
// At this point, the PCB is allocated and nobody else can get it.
// However, it's not in the run queue, so it won't be run. Thus, we
// can turn on interrupts here.
dbprintf ('I', "Before restore interrupt value is 0x%x.\n", CurrentIntrs());
RestoreIntrs (intrs);
dbprintf ('I', "New interrupt value is 0x%x.\n", CurrentIntrs());
// Copy the process name into the PCB.
dstrcpy (pcb->name, name);
//----------------------------------------------------------------------
// This section initializes the memory for this process
//----------------------------------------------------------------------
// For now, we'll use one user page and a page for the system stack.
// For system processes, though, all pages must be contiguous.
// Of course, system processes probably need just a single page for
// their stack, and don't need any code or data pages allocated for them.
pcb->npages = 1;
newPage = MemoryAllocPage ();
if (newPage == 0) {
printf ("aFATAL: couldn't allocate memory - no free pages!\n");
exitsim (); // NEVER RETURNS!
}
pcb->pagetable[0] = MemorySetupPte (newPage);
newPage = MemoryAllocPage ();
if (newPage == 0) {
printf ("bFATAL: couldn't allocate system stack - no free pages!\n");
exitsim (); // NEVER RETURNS!
}
pcb->sysStackArea = newPage * MEMORY_PAGE_SIZE;
//---------------------------------------
// Lab3: initialized pcb member for your scheduling algorithm here
//--------------------------------------
pcb->p_nice = p_nice < 0 ? 0 : p_nice;
pcb->p_info = p_info;
pcb->sleeptime = my_timer_get();
pcb->estcpu = 0;
pcb->prio = PUSER;
pcb->processed = 1 - processedFlag;
pcb->estcputime = 0;
//----------------------------------------------------------------------
// Stacks grow down from the top. The current system stack pointer has
// to be set to the bottom of the interrupt stack frame, which is at the
// high end (address-wise) of the system stack.
stackframe = ((uint32 *)(pcb->sysStackArea + MEMORY_PAGE_SIZE)) -
(PROCESS_STACK_FRAME_SIZE + 8);
// The system stack pointer is set to the base of the current interrupt
// stack frame.
pcb->sysStackPtr = stackframe;
// The current stack frame pointer is set to the same thing.
pcb->currentSavedFrame = stackframe;
dbprintf ('p',
"Setting up PCB @ 0x%x (sys stack=0x%x, mem=0x%x, size=0x%x)\n",
pcb, pcb->sysStackArea, pcb->pagetable[0],
pcb->npages * MEMORY_PAGE_SIZE);
//----------------------------------------------------------------------
// This section sets up the stack frame for the process. This is done
// so that the frame looks to the interrupt handler like the process
// was "suspended" right before it began execution. The standard
// mechanism of swapping in the registers and returning to the place
// where it was "interrupted" will then work.
//----------------------------------------------------------------------
// The previous stack frame pointer is set to 0, meaning there is no
// previous frame.
stackframe[PROCESS_STACK_PREV_FRAME] = 0;
// Set the base of the level 1 page table. If there's only one page
// table level, this is it. For 2-level page tables, put the address
// of the level 1 page table here. For 2-level page tables, we'll also
// have to build up the necessary tables....
stackframe[PROCESS_STACK_PTBASE] = (uint32)&(pcb->pagetable[0]);
// Set the size (maximum number of entries) of the level 1 page table.
// In our case, it's just one page, but it could be larger.
stackframe[PROCESS_STACK_PTSIZE] = pcb->npages;
// Set the number of bits for both the level 1 and level 2 page tables.
// This can be changed on a per-process basis if desired. For now,
// though, it's fixed.
stackframe[PROCESS_STACK_PTBITS] = (MEMORY_L1_PAGE_SIZE_BITS
+ (MEMORY_L2_PAGE_SIZE_BITS << 16));
if (isUser) {
dbprintf ('p', "About to load %s\n", name);
fd = ProcessGetCodeInfo (name, &start, &codeS, &codeL, &dataS, &dataL);
if (fd < 0) {
// Free newpage and pcb so we don't run out...
ProcessFreeResources (pcb);
return (-1);
}
dbprintf ('p', "File %s -> start=0x%08x\n", name, start);
dbprintf ('p', "File %s -> code @ 0x%08x (size=0x%08x)\n", name, codeS,
codeL);
dbprintf ('p', "File %s -> data @ 0x%08x (size=0x%08x)\n", name, dataS,
dataL);
while ((n = ProcessGetFromFile (fd, buf, &addr, sizeof (buf))) > 0) {
dbprintf ('p', "Placing %d bytes at vaddr %08x.\n", n, addr - n);
// Copy the data to user memory. Note that the user memory needs to
// have enough space so that this copy will succeed!
MemoryCopySystemToUser (pcb, buf, addr - n, n);
}
FsClose (fd);
stackframe[PROCESS_STACK_ISR] = PROCESS_INIT_ISR_USER;
// Set the initial stack pointer correctly. Currently, it's just set
// to the top of the (single) user address space allocated to this
// process.
str = (char *)param;
stackframe[PROCESS_STACK_IREG+29] = MEMORY_PAGE_SIZE - SIZE_ARG_BUFF;
// Copy the initial parameter to the top of stack
MemoryCopySystemToUser (pcb, (char *)str,
(char *)stackframe[PROCESS_STACK_IREG+29],
SIZE_ARG_BUFF-32);
offset = get_argument((char *)param);
dum[2] = MEMORY_PAGE_SIZE - SIZE_ARG_BUFF + offset;
for(count=3;;count++)
{
offset=get_argument(NULL);
dum[count] = MEMORY_PAGE_SIZE - SIZE_ARG_BUFF + offset;
if(offset==0)
{
break;
}
}
dum[0] = count-2;
dum[1] = MEMORY_PAGE_SIZE - SIZE_ARG_BUFF - (count-2)*4;
MemoryCopySystemToUser (pcb, (char *)dum,
(char *)(stackframe[PROCESS_STACK_IREG+29]-count*4),
(count)*sizeof(uint32));
stackframe[PROCESS_STACK_IREG+29] -= 4*count;
// Set the correct address at which to execute a user process.
stackframe[PROCESS_STACK_IAR] = (uint32)start;
pcb->flags |= PROCESS_TYPE_USER;
} else {
// Set r31 to ProcessExit(). This will only be called for a system
// process; user processes do an exit() trap.
stackframe[PROCESS_STACK_IREG+31] = (uint32)ProcessExit;
// Set the stack register to the base of the system stack.
stackframe[PROCESS_STACK_IREG+29]=pcb->sysStackArea + MEMORY_PAGE_SIZE-32;
// Set the initial parameter properly by placing it on the stack frame
// at the location pointed to by the "saved" stack pointer (r29).
*((uint32 *)(stackframe[PROCESS_STACK_IREG+29])) = param;
// Set up the initial address at which to execute. This is done by
// placing the address into the IAR slot of the stack frame.
stackframe[PROCESS_STACK_IAR] = (uint32)func;
// Set the initial value for the interrupt status register
stackframe[PROCESS_STACK_ISR] = PROCESS_INIT_ISR_SYS;
// Mark this as a system process.
pcb->flags |= PROCESS_TYPE_SYSTEM;
}
// Place the PCB onto the run queue.
intrs = DisableIntrs ();
QueueInsertLast (&runQueue[pcb->prio/4], l);
RestoreIntrs (intrs);
// If this is the first process, make it the current one
if (currentPCB == NULL) {
dbprintf ('p', "Setting currentPCB=0x%x, stackframe=0x%x\n",
pcb, pcb->currentSavedFrame);
currentPCB = pcb;
}
dbprintf ('p', "Leaving ProcessFork (%s)\n", name);
// Return the process number (found by subtracting the PCB number
// from the base of the PCB array).
return (pcb - pcbs);
}
//----------------------------------------------------------------------
//
// ProcessSchedule
//
// Schedule the next process to run. If there are no processes to
// run, exit. This means that there should be an idle loop process
// if you want to allow the system to "run" when there's no real
// work to be done.
//
// NOTE: the scheduler should only be called from a trap or interrupt
// handler. This way, interrupts are disabled. Also, it must be
// called consistently, and because it might be called from an interrupt
// handler (the timer interrupt), it must ALWAYS be called from a trap
// or interrupt handler.
//
// Note that this procedure doesn't actually START the next process.
// It only changes the currentPCB and other variables so the next
// return from interrupt will restore a different context from that
// which was saved.
//
//----------------------------------------------------------------------
// You should modify this function to use 4.4BSD scheduling policy
//
void
ProcessSchedule ()
{
PCB *pcb;
int i;
int empty;
int count = 0;
float pinfotime;
PCB* tailPtrs[32];
PCB *curr;
total_num_quanta++;
currentPCB->estcpu++;
currentPCB->estcputime++;
if (currentPCB->p_info) {
pinfotime = currentPCB->estcputime *.1;
printf(TIMESTRING1, (int)GetCurrentPid());
printf(TIMESTRING2, pinfotime);
printf(TIMESTRING3, (int)GetCurrentPid());
printf(TIMESTRING4, currentPCB->prio);
}
empty = 1;
for (i = 0; i < 32; i++) {
count += QueueLength(&runQueue[i]);
}
dbprintf ('p', "Now entering ProcessSchedule (cur=0x%x, %d ready)\n",
currentPCB, count);
// The OS exits if there's no runnable process. This is a feature, not a
// bug. An easy solution to allowing no runnable "user" processes is to
// have an "idle" process that's simply an infinite loop.
if (!count) {
printf ("No runnable processes - exiting!\n");
exitsim (); // NEVER RETURNS
}
dbprintf('p', "About to check if estcpu is divisible by 4 (cur=0x%x\n", currentPCB);
if ((int)currentPCB->estcputime % 4 == 0) {
//printf("Updating prio");
currentPCB->prio = PUSER + (int)(currentPCB->estcpu/4) + 2*currentPCB->p_nice;
}
dbprintf('p', "About to move to end of queue (cur=0x%x\n", currentPCB);
// Move the front of the queue to the end, if it is the running process.
for (i = 0; i < 32; i++) {
pcb = (PCB *)((QueueFirst (&runQueue[i]))->object);
if (pcb == currentPCB)
{
QueueRemove(&pcb->l);
QueueInsertLast(&runQueue[pcb->prio/4], &pcb->l);
break;
}
}
dbprintf('p', "Before decay (cur=0x%x\n", currentPCB);
//decay
if (!(total_num_quanta % 10)) {
//printf("Looping through all to update everything");
for (i = 0; i < 32; i++) { // loop through each queue
if (!QueueLength(&runQueue[i]))
continue;
curr = QueueFirst(&runQueue[i])->object;
dbprintf('p', "Processing PCB in queue %d: 0x%x\n", i, curr);
while (curr && curr->processed != processedFlag) { // all the elements not previously processed in the queue
curr->estcpu = 2.0f/(2 + 1) *curr->estcpu + curr->p_nice;
curr->prio = PUSER + (int)(curr->estcpu/4) + 2*curr->p_nice;
curr->processed = processedFlag;
QueueRemove(&curr->l);
QueueInsertLast(&runQueue[curr->prio/4], &curr->l);
curr = QueueFirst(&runQueue[i])->object;
dbprintf('p', "Processing PCB in queue %d: 0x%x\n", i, curr);
}
}
processedFlag = 1 - processedFlag;
}
// Now, run the one at the head of the queue.
dbprintf ('p',"About to switch 0x%x", currentPCB);
for (i = 0; i < 32; i++) {
if (!QueueLength(&runQueue[i]))
continue;
pcb = (PCB *)((QueueFirst (&runQueue[i]))->object);
currentPCB = pcb;
dbprintf ('p',"About to switch to PCB 0x%x,flags=0x%x @ 0x%x\n",
pcb, pcb->flags,
pcb->sysStackPtr[PROCESS_STACK_IAR]);
break;
}
// Clean up zombie processes here. This is done at interrupt time
// because it can't be done while the process might still be running
while (!QueueEmpty (&zombieQueue)) {
pcb = (PCB *)(QueueFirst (&zombieQueue)->object);
dbprintf ('p', "Freeing zombie PCB 0x%x.\n", pcb);
QueueRemove (&pcb->l);
ProcessFreeResources (pcb);
}
// Set the timer so this process gets at most a fixed quantum of time.
TimerSet (processQuantum);
dbprintf ('p', "Leaving ProcessSchedule (cur=0x%x)\n", currentPCB);
}
//----------------------------------------------------------------------
//
// ProcessSchedule
//
// Schedule the next process to run. If there are no processes to
// run, exit. This means that there should be an idle loop process
// if you want to allow the system to "run" when there's no real
// work to be done.
//
// NOTE: the scheduler should only be called from a trap or interrupt
// handler. This way, interrupts are disabled. Also, it must be
// called consistently, and because it might be called from an interrupt
// handler (the timer interrupt), it must ALWAYS be called from a trap
// or interrupt handler.
//
// Note that this procedure doesn't actually START the next process.
// It only changes the currentPCB and other variables so the next
// return from interrupt will restore a different context from that
// which was saved.
//
//----------------------------------------------------------------------
// You should modify this function to use 4.4BSD scheduling policy
//
void
ProcessSchedule ()
{
PCB *pcb;
int i, j, n;
int atEndOfQueue = FALSE; // To be used as a boolean value
Link *links[32];
// The OS exits if there's no runnable process. This is a feature, not a
// bug. An easy solution to allowing no runnable "user" processes is to
// have an "idle" process that's simply an infinite loop.
/* if (QueueEmpty (&runQueue)) {
printf ("No runnable processes - exiting!\n");
exitsim (); // NEVER RETURNS
}*/
dbprintf('p', "Entering ProcessSchedule [context switch] with current PCB: %p\n",currentPCB);
currentPCB->p_quanta++;
totalQuanta++;
pcb = ProcessHighestPriority();
currentPCB->runtime += my_timer_get() - startTime;
if (currentPCB->p_info == 1) {
printf(TIMESTRING1, currentPCB - pcbs);
printf(TIMESTRING2, currentPCB->runtime / (float)1000);
printf(TIMESTRING3, currentPCB - pcbs, currentPCB->prio);
}
startTime = my_timer_get();
if (!pcb) {
printf ("No runnable processes - exiting!\n");
exitsim ();
}
dbprintf('p', "PCB (%p) currentPCB (%p)\n",pcb,currentPCB);
// If last run process is still the highest priority (ie. not asleep/a zombie)
if (pcb == currentPCB) {
currentPCB->estcpu++;
QueueRemove (&pcb->l);
QueueInsertLast (&runQueue[pcb->runQueueNum], &pcb->l);
dbprintf('p', "\tProcess quanta: %i estcpu: %i\n",currentPCB->p_quanta,currentPCB->estcpu);
if((currentPCB->p_quanta % PROCESS_QUANTA_MAX) == 0) {
dbprintf('p', "Recalculating priority of currentPCB\n");
currentPCB->prio = PUSER + (currentPCB->estcpu/4) + (2*currentPCB->p_nice);
dbprintf('p', "run queue: %i new run queue: %i prio: %i\n",currentPCB->runQueueNum,currentPCB->prio/4,currentPCB->prio);
currentPCB->runQueueNum = currentPCB->prio/4;
QueueRemove(¤tPCB->l);
QueueInsertLast(&runQueue[currentPCB->runQueueNum], ¤tPCB->l);
dbprintf('p', "Recalculated priority\n");
}
}
if(totalQuanta % TOTAL_QUANTA_MAX == 0) {
dbprintf('p', "Full reshuffle\n");
// dbprintf('p', "Process quanta exceeded max\n");
// Store all the tails of all of the RunQueues
for(i = 0; i < 32; i++) {
links[i] = QueueLast(&runQueue[i]);
}
dbprintf('p', "Last links registered\n");
for(i = 0; i < 32; i++) {
// if(QueueEmpty(&runQueue[i])) atEndOfQueue = TRUE;
n = (&runQueue[i])->nitems;
// while(!atEndOfQueue) {
for (j = 0; j < n; j++) {
pcb = (PCB *)((QueueFirst(&runQueue[i]))->object);
pcb->estcpu = (int)((((float)2 * pcb->load)/((float)2 * pcb->load + 1)) * pcb->estcpu) + pcb->p_nice; // Decay the estimated CPU time of all processes
pcb->prio = PUSER + (pcb->estcpu/4) + (2 * pcb->p_nice); // Recalculate the priority of all processes
dbprintf('p', "\tRun queue shift (%p->%d)\n",pcb,pcb->prio);
dbprintf('p', "At link: %p for last link: %p\n",&pcb->l,links[i]);
if(links[i] == &pcb->l || (&pcb->l)->next == NULL) atEndOfQueue = TRUE;
pcb->runQueueNum = pcb->prio/4;
QueueRemove(&pcb->l);
QueueInsertLast(&runQueue[pcb->runQueueNum], &pcb->l);
}
}
pcb = ProcessHighestPriority();
if (currentPCB == pcb) {
QueueRemove(¤tPCB->l);
QueueInsertLast(&runQueue[currentPCB->runQueueNum], ¤tPCB->l);
}
}
//}
pcb = ProcessHighestPriority();
// }
currentPCB = pcb;
// currentPCB = ProcessHighestPriority();
// Move the front of the queue to the end, if it is the running process.
/*
pcb = (PCB *)((QueueFirst (&runQueue))->object);
if (pcb == currentPCB)
{
QueueRemove (&pcb->l);
QueueInsertLast (&runQueue, &pcb->l);
}
// Now, run the one at the head of the queue.
pcb = (PCB *)((QueueFirst (&runQueue))->object);
currentPCB = pcb;
dbprintf ('p',"About to switch to PCB 0x%x,flags=0x%x @ 0x%x\n",
pcb, pcb->flags,
pcb->sysStackPtr[PROCESS_STACK_IAR]);
*/
// Clean up zombie processes here. This is done at interrupt time
// because it can't be done while the process might still be running
while (!QueueEmpty (&zombieQueue)) {
pcb = (PCB *)(QueueFirst (&zombieQueue)->object);
dbprintf ('p', "Freeing zombie PCB 0x%x.\n", pcb);
QueueRemove (&pcb->l);
ProcessFreeResources (pcb);
}
// Set the timer so this process gets at most a fixed quantum of time.
TimerSet (processQuantum);
dbprintf ('p', "Leaving ProcessSchedule (cur=0x%x)\n", currentPCB);
}
