int Xinu_Default_Scheduling() {
register struct pentry *optr; /* pointer to old process entry */
register struct pentry *nptr; /* pointer to new process entry */
/* no switch needed if current process priority higher than next*/
if (((optr = &proctab[currpid])->pstate == PRCURR) && (lastkey(rdytail) < optr->pprio)) {
return (OK);
}
/* force context switch */
if (optr->pstate == PRCURR) {
optr->pstate = PRREADY;
insert(currpid, rdyhead, optr->pprio);
}
/* remove highest priority process at end of ready list */
nptr = &proctab[(currpid = getlast(rdytail))];
nptr->pstate = PRCURR; /* mark it currently running */
#ifdef RTCLOCK
preempt = QUANTUM; /* reset preemption counter */
#endif
ctxsw((int) &optr->pesp, (int) optr->pirmask, (int) &nptr->pesp, (int) nptr->pirmask);
/* The OLD process returns here when resumed. */
return OK;
}
xexecl(void (*pf)(), int parm)
{
struct pentry *pptr;
char *saddr;
int *sp1;
int ps;
int dummy;
disable(ps);
pptr = &proctab[currpid];
pptr->phasmsg = 0;
sp1 = (int *)(pptr->pbase + pptr->plen);
pptr->pargs = 1;
*(--sp1) = parm;
*(--sp1) = (int) INITRET;
*(--sp1)= (int) pf;
--sp1;
*(--sp1) = INITF;
sp1 -= 2;
pptr->pregs = sp1;
pptr->paddr = pf;
ctxsw(&dummy, &pptr->pregs);
} /* xexecl */
/*------------------------------------------------------------------------
* resched -- reschedule processor to highest priority ready process
*
* Notes: Upon entry, currpid gives current process id.
* Proctab[currpid].pstate gives correct NEXT state for
* current process if other than PRCURR.
*------------------------------------------------------------------------
*/
int resched()
{
register struct pentry *optr; /* pointer to old process entry */
register struct pentry *nptr; /* pointer to new process entry */
register int pflag;
char *oldStackPtr = NULL;
proctab[currpid].time = proctab[currpid].time + tod
- proctab[currpid].oldtime;
optr = &proctab[currpid];
pflag = sys_pcxget();
if ( optr->pstate == PRCURR ) {
/* no switch needed if current prio. higher than next */
/* or if rescheduling is disabled ( pflag == 0 ) */
if ( pflag == 0 || lastkey(rdytail) < optr->pprio )
return;
/* force context switch */
optr->pstate = PRREADY;
insert(currpid,rdyhead,optr->pprio);
} else if ( pflag == 0 ) {
kprintf("pid=%d state=%d name=%s",
currpid,optr->pstate,optr->pname);
panic("Reschedule impossible in this state");
}
/* remove highest priority process at end of ready list */
nptr = &proctab[(currpid=getlast(rdytail))];
nptr->pstate = PRCURR; /* mark it currently running */
preempt = QUANTUM; /* reset preemption counter */
_pglob = nptr->pglob; /* retrieve global environment */
proctab[currpid].oldtime=tod;
if (!optr->pregs || !nptr->pregs)
{
kprintf("Rescheduling failed: pregs = 0\n");
return;
}
/* if (!debug_log)
debug_log = xinu_open("resched.log", O_RDWR|O_CREAT|O_TRUNC);
dprintf(1, "Old: %s, New: %s\n", optr->pname, nptr->pname);*/
oldStackPtr = optr->pregs;
ctxsw(&optr->pregs,&nptr->pregs);
if (currpid != 0 && optr->pregs > optr->pbase + optr->plen)
panic("stack overflow");
if (optr->phastrap) {
optr->phastrap = FALSE; /* mark trap as serviced */
if (optr->ptfn != NULL)
(*optr->ptfn)(optr->ptarg);
}
/* The OLD process returns here when resumed. */
return;
}
/* Aging Scheduler */
int aging_resched()
{
register struct qent *oqptr; /* pointer to the currently running process in queue entry table */
register struct pentry *opptr; /* pointer to the currently running process in process entry table */
register struct qent *nqptr; /* pointer to the newly selected process in queue entry table */
register struct pentry *npptr; /* pointer to the newly selected process in process entry table */
int opid = currpid;
/* no switch needed if current process priority higher than next*/
oqptr = &q[opid];
opptr = &proctab[opid];
/* set the priority of current process to base priority */
q[currpid].qkey = proctab[currpid].pprio;
if ( ( opptr->pstate == PRCURR) && (lastkey(rdytail) < oqptr->qkey) ) {
updprocprio(); /* update priorities of all the processes in ready queue */
#ifdef RTCLOCK
preempt = QUANTUM; /* reset preemption counter */
#endif
return(OK);
}
/* remove highest priority process at end of ready list */
npptr = &proctab[ (currpid = getlast(rdytail)) ];
npptr->pstate = PRCURR; /* mark it currently running */
updprocprio(); /* update priorities of all the processes in ready queue */
/* put old process in ready queue if it is the current executing process */
if (opptr->pstate == PRCURR) {
opptr->pstate = PRREADY;
insert(opid,rdyhead,opptr->pprio);
}
#ifdef RTCLOCK
preempt = QUANTUM; /* reset preemption counter */
#endif
ctxsw((int)&opptr->pesp, (int)opptr->pirmask, (int)&npptr->pesp, (int)npptr->pirmask);
/* The OLD process returns here when resumed. */
return OK;
}
/**
* Reschedule processor to highest priority ready thread.
* Upon entry, thrcurrent gives current thread id.
* Threadtab[thrcurrent].pstate gives correct NEXT state
* for current thread if other than THRREADY.
* @return OK when the thread is context switched back
*/
int resched(void)
{
uchar asid; /* address space identifier */
struct thrent *throld; /* old thread entry */
struct thrent *thrnew; /* new thread entry */
if (resdefer > 0)
{ /* if deferred, increase count & return */
resdefer++;
return (OK);
}
throld = &thrtab[thrcurrent];
throld->intmask = disable();
if (THRCURR == throld->state)
{
if (nonempty(readylist) && (throld->prio > firstkey(readylist)))
{
restore(throld->intmask);
return OK;
}
throld->state = THRREADY;
insert(thrcurrent, readylist, throld->prio);
}
/* get highest priority thread from ready list */
thrcurrent = dequeue(readylist);
thrnew = &thrtab[thrcurrent];
thrnew->state = THRCURR;
/* change address space identifier to thread id */
asid = thrcurrent & 0xff;
#if 0
// XXX Fix this later?
asm("mtc0 %0, $10": :"r"(asid));
#endif
restore(thrnew->intmask);
ctxsw(&throld->stkptr, &thrnew->stkptr);
/* old thread returns here when resumed */
restore(throld->intmask);
return OK;
}
/**
* Reschedule processor to next ready process.
* Upon entry, currpid gives current process id. Proctab[currpid].pstate
* gives correct NEXT state for current process if other than PRREADY.
* @return OK when the process is context switched back
*/
syscall resched(void)
{
irqmask im;
pcb *oldproc; /* pointer to old process entry */
pcb *newproc; /* pointer to new process entry */
short head, tail;
im = disable();
oldproc = &proctab[ currpid ];
/* Aging implemented */
if(AGING)
{
head = queuehead(readylist);
head = queuetab[head].next;
tail = queuetail(readylist);
while(head != tail)
{
queuetab[head].key++;
head = queuetab[head].next;
}
}
/* place current process at end of ready queue */
if (PRCURR == oldproc->state)
{
oldproc->state = PRREADY;
prioritize(currpid, readylist, oldproc->priority);
}
/* remove first process in ready queue */
currpid = dequeue(readylist);
newproc = &proctab[ currpid ];
newproc->state = PRCURR; /* mark it currently running */
#if PREEMPT
preempt = QUANTUM; /* reset preemption counter */
#endif
ctxsw(&oldproc->stkptr, &newproc->stkptr);
/* The OLD process returns here when resumed. */
restore(im);
return OK;
}
/*------------------------------------------------------------------------
* resched_lab1 - Reschedule processor to highest priority eligible process
*------------------------------------------------------------------------
*/
void resched_lab1(void) /* Assumes interrupts are disabled */
{
struct procent *ptold; /* Ptr to table entry for old process */
struct procent *ptnew; /* Ptr to table entry for new process */
/* If rescheduling is deferred, record attempt and return */
if (Defer.ndefers > 0) {
Defer.attempt = TRUE;
return;
}
/* Point to process table entry for the current (old) process */
ptold = &proctab[currpid];
if (ptold->prstate == PR_CURR) { /* Process remains eligible */
if (ptold->prprio > firstkey(readylist)) {
return;
}
/* Old process will no longer remain current */
ptold->prstate = PR_READY;
insert(currpid, readylist, ptold->prprio);
}
/* Force context switch to highest priority ready process */
currpid = dequeue(readylist);
ptnew = &proctab[currpid];
ptnew->prstate = PR_CURR;
preempt = QUANTUM; /* Reset time slice for process */
ctxsw(&ptold->prstkptr, &ptnew->prstkptr);
// LAB 4Q3: Invoke the handleCallback
handleCallback();
/* Old process returns here when resumed */
return;
}
/*
* This function makes the current process block state.
*/
int dskresched() {
register struct pentry *optr;
register struct pentry *nptr;
STATWORD ps;
disable(ps);
optr = &proctab[currpid];
optr -> pstate = PRSUSP;
nptr = &proctab[(currpid = getlast(rdytail))];
nptr -> pstate = PRCURR;
#ifdef RTCLOCK
preempt = QUANTUM;
#endif
restore(ps);
ctxsw((int)&optr -> pesp, (int)optr -> pirmask, (int)&nptr -> pesp, (int)nptr -> pirmask);
return OK;
}
void _resched_aging(struct pentry *optr, struct pentry *nptr)
{
int oldpreempt = preempt;
preempt = MAXINT;
/* Loop through everything in the queue and increase each entries
priority by a factor of 1.2 */
int next = q[rdyhead].qnext;
while (q[next].qnext != EMPTY) {
q[next].qkey = min(MAX_PRIORITY, ceil(q[next].qkey * 1.2));
next = q[next].qnext;
}
/* Put the current process back into the queue with its base
priority */
if (optr->pstate == PRCURR) {
optr->pstate = PRREADY;
insert(currpid, rdyhead, optr->pprio);
}
/* Now get the item with the highest priority */
int oldcurrpid = currpid;
currpid = getlast(rdytail);
/* If the process from the end of the list is the current process,
no context switch is necessary */
if (currpid == oldcurrpid) {
optr->pstate = PRCURR;
preempt = oldpreempt;
return;
}
/* Otherwise, switch contexts to the new current process */
nptr = &proctab[currpid];
nptr->pstate = PRCURR;
#ifdef RTCLOCK
preempt = QUANTUM; /* Reset preempt counter */
#endif
ctxsw((int)&optr->pesp, (int)optr->pirmask, (int)&nptr->pesp, (int)nptr->pirmask);
return;
}
/**
* Reschedule processor to next ready process.
* Upon entry, currpid gives current process id. Proctab[currpid].pstate
* gives correct NEXT state for current process if other than PRREADY.
* @return OK when the process is context switched back
*/
syscall resched(void)
{
pcb *oldproc; /* pointer to old process entry */
pcb *newproc; /* pointer to new process entry */
oldproc = &proctab[ currpid ];
/* place current process at end of ready queue */
if (PRCURR == oldproc->state)
{
oldproc->state = PRREADY;
enqueue(currpid, readylist);
}
/* remove first process in ready queue */
currpid = dequeue(readylist);
newproc = &proctab[ currpid ];
newproc->state = PRCURR; /* mark it currently running */
ctxsw(&oldproc->stkptr, &newproc->stkptr);
/* The OLD process returns here when resumed. */
return OK;
}
int RealTimeProcess_Scheduling(int newEpoch, struct pentry *optr, struct pentry *nptr) {
optr->quantumleft = preempt;
if (optr->quantumleft <= 0)
optr->quantumleft = 0;
if (newEpoch == TRUE) {
int i = 0;
struct pentry *p;
for (i = 0; i < NPROC; i++) {
p = &proctab[i];
if (p->pstate == PRFREE || p->real == FALSE)
continue;
else {
p->quantum = 100;
p->quantumleft = p->quantum;
}
}
}
if (optr->real == TRUE && optr->quantumleft > 0 && optr->pstate == PRCURR && ((newEpoch == FALSE) || isempty(realrdyhead))) {
/*
* Current process has quantum left and wants to be in PCURR state
* Or
* It is a newEpoch, then as per Round-Robin, next process must be selected not optr again.
* But if this is the only process, then it has to be chosen.
* Also, if it is newEpoch it definitely means current process does not want to return.
*/
preempt = optr->quantumleft;
return OK;
} else if (optr->pstate != PRCURR || optr->quantumleft <= 0 || optr->real == FALSE || (!isempty(realrdyhead) && newEpoch == TRUE && optr->quantumleft > 0 && optr->pstate == PRCURR)) {
/*
* Currpid does not want to be PRCURR state any more or its quantum exhausted for this epoch.
* Also, currpid want to execute but RoundRobin-wise next process is to be selected
*/
if (isempty(realrdyhead))
return NEWEPOCH;
else {
/*
* Choosing next process with quantumleft > 0
*/
int newprocPID = 0;
int k = 0;
for (k = q[realrdytail].qprev; k != realrdyhead; k = q[k].qprev) {
if (proctab[k].quantumleft > 0) {
newprocPID = k;
break;
}
}
if (newprocPID != realrdyhead) {
if (optr->real == TRUE && optr->pstate == PRCURR) { //Just like in Xinu Scheduling
optr->pstate = PRREADY;
insert(currpid, realrdyhead, 1);
} else if (optr->real == FALSE && optr->pstate == PRCURR) {
optr->pstate = PRREADY;
insert(currpid, rdyhead, optr->pprio);
}
nptr = &proctab[newprocPID];
nptr->pstate = PRCURR;
dequeue(newprocPID);
currpid = newprocPID;
preempt = nptr->quantumleft;
ctxsw((int) &optr->pesp, (int) optr->pirmask, (int) &nptr->pesp, (int) nptr->pirmask);
return OK;
} else
return NEWEPOCH;
}
}
return SYSERR;
}
int Linux_22_Scheduling() {
/*
* preempt = no. of clock ticks remaining
*/
register struct pentry *optr; /* pointer to old process entry */
register struct pentry *nptr; /* pointer to new process entry */
int newEpoch = FALSE;
choose: optr = &proctab[currpid];
int optrOldPrio = optr->goodness - optr->quantumleft; //Even If optr's prio has been changed, difference gives old priority
optr->goodness = optrOldPrio + preempt;
optr->quantumleft = preempt;
if (optr->quantumleft <= 0 || currpid == NULLPROC) {
optr->quantumleft = 0; //No more CPU time left
optr->goodness = 0; //Exhausted allocated CPU time
}
//Find, of all runnable processes which has highest goodness
int maxGoodness = 0;
int k = 0;
int newprocPID = 0;
for (k = q[rdytail].qprev; k != rdyhead; k = q[k].qprev) {
if (proctab[k].goodness > maxGoodness) {
newprocPID = k;
maxGoodness = proctab[k].goodness;
}
}
if (maxGoodness == 0 && (optr->pstate != PRCURR || optr->quantumleft == 0)) {
/*
* NEW EPOCH
* MaxGoodness is zero, it means runnable processes are other old process
* have exhausted CPU and new epoch has to begin
* For Current old process, if counter = 0, exhausted CPU, forced to next epoch
* If it does not want to stay PRCURR despite CPU time, next epoch
*/
if (newEpoch == FALSE) {
newEpoch = TRUE;
int i;
struct pentry *p;
for (i = 0; i < NPROC; i++) {
p = &proctab[i];
if (p->pstate == PRFREE)
continue;
else if (p->quantumleft == 0 || p->quantumleft == p->quantum) { //Process either exhausted or not run at all;
p->quantum = p->pprio;
} else {
p->quantum = (p->quantumleft) / 2 + p->pprio;
}
p->quantumleft = p->quantum;
p->goodness = p->quantumleft + p->pprio;
}
preempt = optr->quantumleft;
goto choose;
}
/*
* Now that quantum, counter and goodness are set, choose process with best goodness.
* Since optr is still current process, preempt is set to optr->counter
*/
if (maxGoodness == 0) {
if (currpid == NULLPROC) {
return OK;
} else {
newprocPID = NULLPROC;
if (optr->pstate == PRCURR) { //Just like in Xinu Scheduling
optr->pstate = PRREADY;
insert(currpid, rdyhead, optr->pprio);
}
nptr = &proctab[newprocPID];
nptr->pstate = PRCURR;
dequeue(newprocPID);
currpid = newprocPID;
#ifdef RTCLOCK
preempt = QUANTUM;
#endif
ctxsw((int) &optr->pesp, (int) optr->pirmask, (int) &nptr->pesp, (int) nptr->pirmask);
return OK;
}
}
} else if (optr->goodness >= maxGoodness && optr->goodness > 0 && optr->pstate == PRCURR) {
/*
* Current process has maximum goodness,
* Its goodness is greater than 0.
* If goodness is 0, then all runnable processes have same goodness and they have to
* chosen in Round-Robin manner. Goodness being 0 also means exhausted CPU time.
* So, no need to run it again in this epoch.
* Currpid wants to be CURR state.
* In the same epoch, execute till its counter exhausts i.e, reduces to 0.
*/
preempt = optr->quantumleft;
return OK;
}
/*
* There can be multiple processes with non-zero maxGoodness, in that case
* while iterating readyList from head to tail, we will get the last one and execute it
* Then next from the last with same maxGoodness. Meanwhile if any process enter readyList
* it will not be executed till next epoch as its goodness stays 0.
*/
else if (maxGoodness > 0 && (optr->pstate != PRCURR || optr->quantumleft == 0 || optr->goodness < maxGoodness)) {
/*
* Currpid does not want to be PRCURR state any more even though it has more goodness and CPU time
* Exhausted allocated CPU time, but wants to be PRCURR and has maxGoodness
* Its goodness is less than maxGoodness, and has CPU time and wants to be PRCURR
* Process must be rescheduled and next process must begin.
*/
if (optr->pstate == PRCURR) { //Just like in Xinu Scheduling
optr->pstate = PRREADY;
insert(currpid, rdyhead, optr->pprio);
}
nptr = &proctab[newprocPID];
nptr->pstate = PRCURR;
dequeue(newprocPID);
currpid = newprocPID;
preempt = nptr->quantumleft;
ctxsw((int) &optr->pesp, (int) optr->pirmask, (int) &nptr->pesp, (int) nptr->pirmask);
return OK;
} else
return SYSERR;
}
int NormalQueue_Scheduling(int newEpoch, struct pentry *optr, struct pentry *nptr) {
if (newEpoch) {
int i = 0;
struct pentry *p;
for (i = 0; i < NPROC; i++) {
p = &proctab[i];
if (p->pstate == PRFREE || p->real == TRUE)
continue;
else if (p->quantumleft == 0 || p->quantumleft == p->quantum) { //Process either exhausted or not run at all;
p->quantum = p->pprio;
} else {
p->quantum = (p->quantumleft) / 2 + p->pprio;
}
p->quantumleft = p->quantum;
p->goodness = p->quantumleft + p->pprio;
}
preempt = optr->quantumleft;
}
int optrOldPrio = optr->goodness - optr->quantumleft; //Even If optr's prio has been changed, difference gives old priority
optr->goodness = optrOldPrio + preempt;
optr->quantumleft = preempt;
if (optr->quantumleft <= 0) {
optr->quantumleft = 0; //No more CPU time left
optr->goodness = 0; //Exhausted allocated CPU time
}
if (optr->real == TRUE)
optr->goodness = 0;
//Find, of all runnable processes which has highest goodness
int maxGoodness = 0;
int k = 0;
int newprocPID = 0;
for (k = q[rdyhead].qnext; k != rdytail; k = q[k].qnext) {
if (proctab[k].goodness > maxGoodness) {
newprocPID = k;
maxGoodness = proctab[k].goodness;
}
}
if (maxGoodness == 0 && (optr->pstate != PRCURR || optr->quantumleft == 0)) {
/* NEW EPOCH
* MaxGoodness is zero, it means processes in readylist
* have exhausted CPU and new epoch has to begin
* For Current process, if counter = 0, exhausted CPU, forced to next epoch
* If it does not want to stay PRCURR despite CPU time, next epoch*/
if (newEpoch == TRUE && isempty(realrdyhead)) {
if (optr->real == TRUE && (optr->pstate == PRCURR || optr->pstate == PRREADY)) {
return NEWEPOCH;
} else if (currpid == NULLPROC) {
// kprintf("\tNUM OF USER PROCESSES : %d \n", numproc);
return OK;
} else {
newprocPID = NULLPROC;
if (optr->real == FALSE && optr->pstate == PRCURR) {
optr->pstate = PRREADY;
insert(currpid, rdyhead, optr->pprio);
} else if (optr->real == TRUE && optr->pstate == PRCURR) {
optr->pstate = PRREADY;
insert(currpid, realrdyhead, 1);
}
//kprintf("\t switched to Null process\t");
nptr = &proctab[newprocPID];
nptr->pstate = PRCURR;
dequeue(newprocPID);
currpid = newprocPID;
#ifdef RTCLOCK
preempt = QUANTUM; //reset preemption counter
#endif
ctxsw((int) &optr->pesp, (int) optr->pirmask, (int) &nptr->pesp, (int) nptr->pirmask);
return OK;
}
} else
return NEWEPOCH;
} else if (optr->real == FALSE && optr->goodness >= maxGoodness && optr->goodness > 0 && optr->pstate == PRCURR) {
/*
* Current process has maximum goodness,
* Its goodness is greater than 0.
* Currpid wants to be CURR state.
* In the same epoch, execute till its quantumleft exhausts i.e, reduces to 0.
*/
preempt = optr->quantumleft;
return OK;
} else if (maxGoodness > 0 && (optr->pstate != PRCURR || optr->quantumleft == 0 || optr->goodness < maxGoodness)) {
/*
* Currpid does not want to be PRCURR state any more even though it has more goodness and CPU time
* OR, Exhausted allocated CPU time, but wants to be PRCURR and has maxGoodness
* OR, Its goodness is less than maxGoodness, and has CPU time and wants to be PRCURR
* Process must be rescheduled and next process must begin.
*/
if (optr->real == FALSE && optr->pstate == PRCURR) { //Just like in Xinu Scheduling
optr->pstate = PRREADY;
insert(currpid, rdyhead, optr->pprio);
} else if (optr->real == TRUE && optr->pstate == PRCURR) { //Just like in Xinu Scheduling
optr->pstate = PRREADY;
insert(currpid, realrdyhead, 1);
}
nptr = &proctab[newprocPID];
nptr->pstate = PRCURR;
dequeue(newprocPID);
currpid = newprocPID;
preempt = nptr->quantumleft;
ctxsw((int) &optr->pesp, (int) optr->pirmask, (int) &nptr->pesp, (int) nptr->pirmask);
return OK;
} else
return SYSERR;
}
/*-----------------------------------------------------------------------
* resched -- reschedule processor to highest priority ready process
*
* Notes: Upon entry, currpid gives current process id.
* Proctab[currpid].pstate gives correct NEXT state for
* current process if other than PRREADY.
*------------------------------------------------------------------------
*/
int resched()
{
register struct pentry *optr; /* pointer to old process entry */
register struct pentry *nptr; /* pointer to new process entry */
int itemA, itemB, itemC,proc;
int num, i;
//STATWORD ps;
optr = &proctab[currpid];
if(sched_type==RANDOMSCHED)
{
/*if(count_random==0)
{
count_random++;
enqueue(dequeue(0),queueC_tail);
}*/
if((!nonempty(queueC_head)) && (!nonempty(queueC_head)) && (!nonempty(queueC_head)))
{
return OK;
}
proctab[currpid].quantumLeft = preempt; //quantum used in last execution
if(switched_to_randomsched==1)
{
switched_to_randomsched=0;
proctab[currpid].procCpuTicks += (proctab[currpid].assignedQuantum - preempt);
}
else
{
proctab[currpid].procCpuTicks += (QUANTUM - preempt);
}
//proctab[currpid].procCpuTicks += (QUANTUM - preempt);
/*Make current process as ready*/
if (optr->pstate == PRCURR)
{
//kprintf("\nen inside ");
optr->pstate = PRREADY;
if(((optr->pprio)>=66) && ((optr->pprio)<=99))
{
//kprintf("\nReady Queue A, %s", optr->pname);
enqueue(currpid, queueA_tail);
}
else if(optr->pprio>=33 && optr->pprio<=65)
{
//kprintf("\nReady Queue b, %s", optr->pname);
enqueue(currpid, queueB_tail);
}
else if(optr->pprio>=0 && optr->pprio<=32)
{
//kprintf("\nReady Queue c, %s", optr->pname);
enqueue(currpid, queueC_tail);
//enqueue(0,queueC_tail);
}
}
//srand(1);
generate_random:
num = rand();
//kprintf("\n rand 1: %d", num);
num = (num%97);
//kprintf("\n normalized rand 1: %d", num);
if(num>=50)
{
if(nonempty(queueA_head))
{
itemA = getfirst(queueA_head);
//kprintf("\nresched Queue A, %d",itemA);
nptr = &proctab[ (currpid = itemA)];//getfirst(queueA_head)) ];
nptr->pstate = PRCURR; /* mark it currently running */
#ifdef RTCLOCK
preempt = QUANTUM; /* reset preemption counter */
#endif
ctxsw((int)&optr->pesp, (int)optr->pirmask, (int)&nptr->pesp, (int)nptr->pirmask);
/* The OLD process returns here when resumed. */
return OK;
}
else
goto generate_random;//resched();
}
else if(num>20 && num <50)
{
if(nonempty(queueB_head))
{
itemB = getfirst(queueB_head);
//kprintf("\nresched Queue B, %d, %s",itemB, proctab[itemB].pname);
nptr = &proctab[ (currpid = itemB)];//getfirst(queueB_head)) ];
nptr->pstate = PRCURR; /* mark it currently running */
#ifdef RTCLOCK
preempt = QUANTUM; /* reset preemption counter */
#endif
ctxsw((int)&optr->pesp, (int)optr->pirmask, (int)&nptr->pesp, (int)nptr->pirmask);
/* The OLD process returns here when resumed. */
return OK;
}
else
goto generate_random;//resched();
}
else if(num<=20)
{
if(nonempty(queueC_head))
{
itemC = getfirst(queueC_head);
//kprintf("\nresched Queue C, %d, %s",itemC, proctab[itemC].pname);
nptr = &proctab[ (currpid = itemC)];//getfirst(queueC_head)) ];
nptr->pstate = PRCURR; /* mark it currently running */
#ifdef RTCLOCK
preempt = QUANTUM; /* reset preemption counter */
#endif
ctxsw((int)&optr->pesp, (int)optr->pirmask, (int)&nptr->pesp, (int)nptr->pirmask);
/* The OLD process returns here when resumed. */
return OK;
}
else
goto generate_random;//resched();
}
}
else if(sched_type == LINUXSCHED)
{
//int usedPreempt = preempt;
int highProc;
int oldPriority = proctab[currpid].pprio; //save the current process' priority so that the effect of chprio() or change in priority to the quantum
// or goodness is reflected in new epoch
//int procGoodness = 0;
int startNewEpoch = 1;
//disable(ps);
proctab[currpid].quantumLeft = preempt;
if(switched_to_linuxsched==1)
{
proctab[currpid].runnableProc = 1;
switched_to_linuxsched=0;
proctab[currpid].procCpuTicks += (QUANTUM - preempt);
proctab[currpid].assignedQuantum = proctab[currpid].assignedQuantum -(QUANTUM - preempt);
}
else
{
proctab[currpid].procCpuTicks += (proctab[currpid].assignedQuantum - preempt);
proctab[currpid].assignedQuantum = proctab[currpid].quantumLeft;
}
if(optr->pstate == PRCURR)
{
optr->pstate = PRREADY;
insert(currpid, rdyhead, proctab[currpid].procGoodness);
}
highProc = rdytail;
while(q[highProc].qprev!=rdyhead && q[highProc].qprev>=0 && q[highProc].qprev<NPROC) //q[temp].qnext!=rdytail && q[temp].qnext>=0 && q[temp].qnext<NPROC
{
//kprintf("\t pbdsf%s",proctab[q[highProc].qprev].pname);
if((proctab[q[highProc].qprev].runnableProc == 1) && (proctab[q[highProc].qprev].assignedQuantum > 0 ) ) //q[highProc].qnext!=0 &&
{
//kprintf("\n bacha hai : %d, %s",q[highProc].qprev, proctab[q[highProc].qprev].pname);
startNewEpoch = 0;
break;
}
highProc = q[highProc].qprev;
}
if(startNewEpoch == 1)
{
//kprintf("\nNew Epoch started---*******");
for(i=0; i<NPROC; i++)
{
if(proctab[i].pstate != PRFREE)
{
oldPriority = proctab[i].pprio; //prevent priority change effect in calculation of quantum
//proctab[i].runnableProc = 1;
//calculate quantum of each process either sleeping/waiting or ready
if(proctab[i].runnableProc == 1)
{
if(proctab[i].assignedQuantum > 0)
{
proctab[i].assignedQuantum = (oldPriority + (proctab[i].assignedQuantum /2));
proctab[i].procGoodness = (oldPriority + proctab[i].quantumLeft);
//kprintf("\nNew quantum and goodness %d, %d, %s",proctab[i].assignedQuantum, proctab[i].procGoodness, proctab[i].pname);
}
else
{
proctab[i].assignedQuantum = oldPriority;
proctab[i].procGoodness = 0;//(oldPriority);
//kprintf("\nused up quantum %d, %d, %s",proctab[i].assignedQuantum, proctab[i].procGoodness, proctab[i].pname);
}
}
proctab[i].runnableProc = 1;
//kprintf("\nFinal values of quantum and goodness %d, %d, %s",proctab[i].assignedQuantum, proctab[i].procGoodness, proctab[i].pname);
dequeue(i);
insert(i, rdyhead, proctab[i].procGoodness);
}
}
}
//goodness is to be calculated for process in same epoch also ? -> no
highProc = rdytail;
while(q[highProc].qprev!=rdyhead && q[highProc].qprev>=0 && q[highProc].qprev<NPROC)
{
/*kprintf("\n Highest proc based on goodness %d, %d, %d", q[highProc].qprev, proctab[q[highProc].qprev].procGoodness, proctab[q[highProc].qprev].assignedQuantum);
if(proctab[q[highProc].qprev].pstate == PRREADY)
{
kprintf("\nstate: PRREADY, %d", proctab[q[highProc].qprev].runnableProc);
}*/
if( (proctab[q[highProc].qprev].runnableProc == 1) && (proctab[q[highProc].qprev].assignedQuantum > 0 ) )//&& (proctab[q[highProc].qprev].pstate==PRREADY) && q[highProc].qprev!=0 )
{
//kprintf(" \ninside----------- %d", currpid);
currpid = dequeue(q[highProc].qprev);
//kprintf(" \nnew pid----------- %d", currpid);
//if(currpid != 0)
//{
nptr = &proctab[currpid];
nptr->pstate = PRCURR; /* mark it currently running */
#ifdef RTCLOCK
preempt = nptr->assignedQuantum; /* reset preemption counter */
#endif
ctxsw((int)&optr->pesp, (int)optr->pirmask, (int)&nptr->pesp, (int)nptr->pirmask);
/* The OLD process returns here when resumed. */
return ;// OK;
break;
}
else if( (q[rdyhead].qnext == 0) && (q[rdytail].qprev== 0))
{
//proctab[currpid].assignedQuantum = QUANTUM;
// kprintf(" \ninside----------- %d", currpid);
nptr = &proctab[(currpid=0)];
nptr->pstate = PRCURR; /* mark it currently running */
#ifdef RTCLOCK
preempt = QUANTUM; /* reset preemption counter */
#endif
ctxsw((int)&optr->pesp, (int)optr->pirmask, (int)&nptr->pesp, (int)nptr->pirmask);
/* The OLD process returns here when resumed. */
return;// OK;
break;
}
highProc = q[highProc].qprev;
}
}
else if(sched_type!=RANDOMSCHED && sched_type!=LINUXSCHED)
{
/* no switch needed if current process priority higher than next*/
if ( ( optr->pstate == PRCURR) && (lastkey(rdytail)<optr->pprio))
{
return(OK);
}
/* force context switch */
if (optr->pstate == PRCURR) {
optr->pstate = PRREADY;
insert(currpid,rdyhead,optr->pprio);
}
proctab[currpid].quantumLeft = preempt;
proctab[currpid].procCpuTicks += (QUANTUM - preempt);
/* remove highest priority process at end of ready list */
nptr = &proctab[ (currpid = getlast(rdytail)) ];
nptr->pstate = PRCURR; /* mark it currently running */
#ifdef RTCLOCK
preempt = QUANTUM; /* reset preemption counter */
#endif
ctxsw((int)&optr->pesp, (int)optr->pirmask, (int)&nptr->pesp, (int)nptr->pirmask);
/* The OLD process returns here when resumed. */
return OK;
}
}
/*------------------------------------------------------------------------
* resched - Reschedule processor to highest priority eligible process
*------------------------------------------------------------------------
*/
void resched(void) /* Assumes interrupts are disabled */
{
struct procent *ptold; /* Ptr to table entry for old process */
struct procent *ptnew; /* Ptr to table entry for new process */
/* If rescheduling is deferred, record attempt and return */
if (Defer.ndefers > 0) {
Defer.attempt = TRUE;
return;
}
/* Point to process table entry for the current (old) process */
ptold = &proctab[currpid];
if(ptold->is_real_proc==1)
{
if(ptold->prstate == PR_CURR){
if(ptold->real_prio > queuetab[firstid(60)].real_qkey)
{
return;
}
ptold->prstate = PR_READY;
insert_real(currpid, readylist[60], (double)(ptold->real_prio));
}
}
//if the process is currently executing i.e it is executing currently, then it is considered as CPU bound process
else{
if (ptold->prstate == PR_CURR) { /* Process remains eligible */
/*if (ptold->prprio > firstkey(readylist)) {
return;
}*/
/* Old process will no longer remain current */
if(currpid!=NULLPROC){
ptold->prprio = tstab[ptold->prprio].ts_tqexp;
}
ptold->prstate = PR_READY;
enqueue(currpid, readylist[ptold->prprio]);
}
//if the process is in sleep state, it is considered to be as an I/O bound process
else if(ptold->prstate == PR_SLEEP){
ptold->prprio = tstab[ptold->prprio].ts_slpret;
}
}
/* Force context switch to highest priority ready process */
//Now find the Process with the highest Priority from the ready list and then assign it as the currpid
int i;
for(i=60;i>=0;i--){
if(!isempty(readylist[i]))
{
//enqueue(currpid, readylist[ptold->prprio]);
currpid = dequeue(readylist[i]);
if(currpid ==NULLPROC)
{
if(!isempty(readylist[i]))
{
enqueue(currpid, readylist[i]);
currpid = dequeue(readylist[i]);
}
}
break;
}
}
ptnew = &proctab[currpid];
if(ptnew->is_real_proc==1)
{
preempt = 70;
}
else
{
preempt = tstab[ptnew->prprio].ts_quantum; /* Reset time slice for process */
}
ptnew->prstate = PR_CURR;
ctxsw(&ptold->prstkptr, &ptnew->prstkptr);
//run the call back function
ptnew = &proctab[currpid];
if(ptnew->asigcb == 0){
if(proctab[currpid].func!=NULL && proctab[currpid].prhasmsg==TRUE)
{
*(proctab[currpid].abuf)= proctab[currpid].prmsg;
proctab[currpid].prhasmsg = FALSE;
(*proctab[currpid].func)();
// proctab[currpid].prhasmsg = FALSE;
}
}
if(ptnew->asigcb ==1) {
if(ptnew->optarg == 0)
{
if(ptnew->arecvfunc!=NULL && ptnew->prhasmsg==TRUE)
{
(*ptnew->arecvfunc)();
// ptnew->prhasmsg = FALSE;
}
}
// if(ptnew->optarg>0)
// {
// if(ptnew->alarmfunc!=NULL && ptnew->prhasmsg==TRUE)
// {
if(ptnew->alarm_time>0)
{
if(myglobalclock >= ptnew->alarm_time)
{
ptnew->alarm_time = -1;
(*ptnew->alarmfunc)();
}
}
// ptnew->prhasmsg = FALSE;
// }
// }
// }
}
/* Old process returns here when resumed */
return;
}
void _resched_linux(struct pentry *optr, struct pentry *nptr)
{
int oldpreempt = preempt;
preempt = MAXINT;
/* Copy over however much counter the current process had left */
int counter_diff = proctab[currpid].pcounter - oldpreempt;
proctab[currpid].pcounter -= counter_diff;
/* Check to see if there are any processes on the ready queue
which are able to run and have quantum left */
int done_with_epoch = 1;
int item = q[rdytail].qprev;
/* Loop over backwards, looking for can_run, pstate == PRREADY and
counter > 0 */
while (q[item].qprev != EMPTY) {
/* If we find an eligible process, flag the epoch as not done */
if (proctab[item].pcan_run && (proctab[item].pstate == PRREADY ||
proctab[item].pstate == PRCURR) && proctab[item].pcounter > 0) {
done_with_epoch = 0;
break;
}
/* Move on to the previous item */
item = q[item].qprev;
}
/* If the epoch is over or we have no proceses eligible to execute for this epoch */
if (done_with_epoch) {
/* Make sure the null proc has a counter of 0 */
proctab[NULLPROC].pcounter = 0;
/* Loop over each process */
int pid;
for (pid=1; pid<NPROC; pid++) {
if (proctab[pid].pstate == PRFREE)
continue;
/* Set this process as runnable, since we're starting a new epoch */
proctab[pid].pcan_run = 1;
/* Copy the priority over to the field to use during epochs, since
priority cannot change during runtime */
proctab[pid].pprio2 = proctab[pid].pprio;
/* If this process has quantum left over the threshold, factor that in */
if (proctab[pid].pcounter >= rollover_threshold) {
proctab[pid].pquantum = floor(proctab[pid].pcounter/2) + proctab[pid].pprio2;
proctab[pid].pcounter = proctab[pid].pquantum;
}
/* Otherwise, set it's quantum counter to it's priority */
else {
proctab[pid].pquantum = proctab[pid].pcounter = proctab[pid].pprio2;
}
/* If this process is on the ready queue, make sure it's in the right
spot since it's key may have changed */
if (proctab[pid].pstate == PRREADY) {
int new_goodness = proctab[pid].pcounter + proctab[pid].pprio2;
/* If the new value is between the processes before and after
this one, then it's safe to just change the value */
if (new_goodness >= q[q[pid].qprev].qkey &&
new_goodness <= q[q[pid].qnext].qkey) {
q[pid].qkey = new_goodness;
}
/* If it's not though, we need to dequeue the process and
insert it back in with the new goodness value */
else {
dequeue(pid);
insert(pid, rdyhead, new_goodness);
}
}
}
/* Then put the current process back into the ready queue, if it wants to */
if (optr->pstate == PRCURR) {
optr->pstate = PRREADY;
insert(currpid, rdyhead, proctab[currpid].pcounter + proctab[currpid].pprio2);
}
}
/* Put the current process back into the ready queue */
else if (optr->pstate == PRCURR) {
int new_goodness = optr->pcounter > 0 ? optr->pcounter + optr->pprio2 : 0;
if (new_goodness > lastkey(rdytail)) {
if (currpid != 0)
preempt = optr->pcounter;
else
preempt = QUANTUM;
return;
}
optr->pstate = PRREADY;
insert(currpid, rdyhead, new_goodness);
}
/* Get the item with the highest 'goodness' */
currpid = getlast(rdytail);
/* Otherwise, switch contexts to the new current process */
nptr = &proctab[currpid];
nptr->pstate = PRCURR;
#ifdef RTCLOCK
if (currpid != 0)
preempt = nptr->pcounter;
else
preempt = QUANTUM;
#endif
ctxsw((int)&optr->pesp, (int)optr->pirmask, (int)&nptr->pesp, (int)nptr->pirmask);
return;
}
/*------------------------------------------------------------------------
* resched -- reschedule processor to highest priority ready process
*
* Notes: Upon entry, currpid gives current process id.
* Proctab[currpid].pstate gives correct NEXT state for
* current process if other than PRREADY.
*------------------------------------------------------------------------
*/
int resched()
{
STATWORD PS;
register struct pentry *optr; /* pointer to old process entry */
register struct pentry *nptr; /* pointer to new process entry */
register int i;
disable(PS);
/* no switch needed if current process priority higher than next*/
if ( ( (optr= &proctab[currpid])->pstate == PRCURR) &&
(lastkey(rdytail)<optr->pprio)) {
restore(PS);
return(OK);
}
#ifdef STKCHK
/* make sure current stack has room for ctsw */
asm("movl %esp, currSP");
if (currSP - optr->plimit < 48) {
kprintf("Bad SP current process, pid=%d (%s), lim=0x%lx, currently 0x%lx\n",
currpid, optr->pname,
(unsigned long) optr->plimit,
(unsigned long) currSP);
panic("current process stack overflow");
}
#endif
/* force context switch */
if (optr->pstate == PRCURR) {
optr->pstate = PRREADY;
insert(currpid,rdyhead,optr->pprio);
}
/* remove highest priority process at end of ready list */
nptr = &proctab[ (currpid = getlast(rdytail)) ];
nptr->pstate = PRCURR; /* mark it currently running */
#ifdef notdef
#ifdef STKCHK
if ( *( (int *)nptr->pbase ) != MAGIC ) {
kprintf("Bad magic pid=%d value=0x%lx, at 0x%lx\n",
currpid,
(unsigned long) *( (int *)nptr->pbase ),
(unsigned long) nptr->pbase);
panic("stack corrupted");
}
/*
* need ~16 longs of stack space below, so include that in check
* below.
*/
if (nptr->pesp - nptr->plimit < 48) {
kprintf("Bad SP pid=%d (%s), lim=0x%lx will be 0x%lx\n",
currpid, nptr->pname,
(unsigned long) nptr->plimit,
(unsigned long) nptr->pesp);
panic("stack overflow");
}
#endif /* STKCHK */
#endif /* notdef */
#ifdef RTCLOCK
preempt = QUANTUM; /* reset preemption counter */
#endif
#ifdef DEBUG
PrintSaved(nptr);
#endif
//OS proj 3 modify
write_cr3(nptr->pdbr);
ctxsw(&optr->pesp, optr->pirmask, &nptr->pesp, nptr->pirmask);
#ifdef DEBUG
PrintSaved(nptr);
#endif
/* The OLD process returns here when resumed. */
restore(PS);
return OK;
}
/*------------------------------------------------------------------------
* resched_lab2 - fair scheduler from lab2, need to set lab2flag according to specs
* given in lab2 documentation on 503 course website.
*------------------------------------------------------------------------
*/
void resched_lab2(void)
{
uint32 currTime = clktimemsec;
struct procent *ptold; /* Ptr to table entry for old process */
struct procent *ptnew; /* Ptr to table entry for new process */
/* If rescheduling is deferred, record attempt and return */
if (Defer.ndefers > 0) {
Defer.attempt = TRUE;
return;
}
uint32 addToTotalTime =0;
/* Point to process table entry for the current (old) process */
ptold = &proctab[currpid];
//Update the total processing time for context switched out process
// Handle the case where the counter overflows then get the absolute value of difference
addToTotalTime = (currTime)-(ptold->prctxswintime);
// if the old process id is not of null user then update its total CPU time
// else ignore this step because prcpumsec of null user is already set to max to
// force it to only execute if no other process is ready
if(currpid != 0)
ptold->prcpumsec = ptold->prcpumsec + addToTotalTime;
// totest switches the key for the readylist queue to be tested based on the lab we are running.
// For the lab3, its the priority of the process
// and for lab 4 and 5 it's the prcpumsec, the cpu time given to the process
int32 totest = ptold->prprio;
// Here the totest will be set to the negation of prcpumsec
// because we wan't to maintain using the insert function that
// inserts elements in decreasing order. By this negation of prcpumsec would
// cause the element with the least prcpumsec to be the first to be dequeud at the head.
// Hence, we are followin the rules of the dynamic priority scheduling algorithm
if(lab2flag == 4 || lab2flag == 5)
totest =-(int32)ptold->prcpumsec;
if (ptold->prstate == PR_CURR) { /* Process remains eligible */
if (totest > firstkey(readylist)) {
ptold->prctxswintime = currTime;
if(lab2flag ==5)
reward_ready_waiting();
return;
}
/* Old process will no longer remain current */
if(lab2flag == 5)
reward_ready_waiting();
ptold->prstate = PR_READY;
// The only other place an insert happens is at the ready method
// even there we have chosen to implement a similar strategy of choosing the value
// of key based on the lab that we are dealing with. That is, either to insert
// based on priority or the negation of the prcpumsec spent.
insert(currpid, readylist, totest);
currpid = dequeue(readylist);
}
else
{
//even if the process is in sleep state and calling a reschedule
// we must reward the other processes
// of course, as soon as the process that is dequeued is removed its key value
// would also
if(lab2flag ==5)
reward_ready_waiting();
currpid = dequeue(readylist);
}
/* Force context switch to highest priority ready process */
ptnew = &proctab[currpid];
ptnew->prstate = PR_CURR;
preempt = QUANTUM; /* Reset time slice for process */
//Update the context switch-in time for new process
ptnew->prctxswintime = currTime;
ctxsw(&ptold->prstkptr, &ptnew->prstkptr);
// LAB 4Q3: Invoke the handleCallback
handleCallback();
/* Old process returns here when resumed */
return;
}
/*------------------------------------------------------------------------
* resched -- reschedule processor to highest priority ready process
*
* Notes: Upon entry, currpid gives current process id.
* Proctab[currpid].pstate gives correct NEXT state for
* current process if other than PRREADY.
*------------------------------------------------------------------------
*/
int resched()
{
STATWORD PS;
register struct pentry *optr; /* pointer to old process entry */
register struct pentry *nptr; /* pointer to new process entry */
disable(PS);
/* no switch needed if current process priority higher than next*/
if ( ( (optr= &proctab[currpid])->pstate == PRCURR) &&
(lastkey(rdytail)<optr->pprio)) {
restore(PS);
return(OK);
}
#ifdef STKCHK
/* make sure current stack has room for ctsw */
asm("movl %esp, currSP");
if (currSP - optr->plimit < 48) {
kprintf("Bad SP current process, pid=%d (%s), lim=0x%lx, currently 0x%lx\n",
currpid, optr->pname,
(unsigned long) optr->plimit,
(unsigned long) currSP);
panic("current process stack overflow");
}
#endif
/* force context switch */
if (optr->pstate == PRCURR) {
optr->pstate = PRREADY;
insert(currpid,rdyhead,optr->pprio);
}
/* remove highest priority process at end of ready list */
nptr = &proctab[ (currpid = getlast(rdytail)) ];
nptr->pstate = PRCURR; /* mark it currently running */
#ifdef notdef
#ifdef STKCHK
if ( *( (int *)nptr->pbase ) != MAGIC ) {
kprintf("Bad magic pid=%d value=0x%lx, at 0x%lx\n",
currpid,
(unsigned long) *( (int *)nptr->pbase ),
(unsigned long) nptr->pbase);
panic("stack corrupted");
}
/*
* need ~16 longs of stack space below, so include that in check
* below.
*/
if (nptr->pesp - nptr->plimit < 48) {
kprintf("Bad SP pid=%d (%s), lim=0x%lx will be 0x%lx\n",
currpid, nptr->pname,
(unsigned long) nptr->plimit,
(unsigned long) nptr->pesp);
panic("stack overflow");
}
#endif /* STKCHK */
#endif /* notdef */
#ifdef RTCLOCK
preempt = QUANTUM; /* reset preemption counter */
#endif
#ifdef DEBUG
PrintSaved(nptr);
#endif
// When performing a context switch between processes we must also
// switch between memory spaces. This is accomplished by adjusting
// the PDBR register with every context switch.
//
// 5 - Context switch
// - every process has separate page directory
// - before ctxsw() load CR3 with the process' PDBR
set_PDBR(VA2VPNO(nptr->pd));
#if DUSTYDEBUG
kprintf("switching to process %d\n", (nptr - proctab));
#endif
ctxsw(&optr->pesp, optr->pirmask, &nptr->pesp, nptr->pirmask);
#ifdef DEBUG
PrintSaved(nptr);
#endif
/* The OLD process returns here when resumed. */
restore(PS);
return OK;
}
/* ------------------------------------------------------------------------
* resched_lab3 - Multi-feedback queue will now be the default scheduler going forward
* This is the scheduler from lab3 that achieves constant time dequeue
* since the size of the levels in the dispatch table is a fixed number
*-------------------------------------------------------------------------
*/
void resched_lab3(void)
{
uint32 currTime = clktimemsec;
struct procent *ptold; /* Ptr to table entry for old process */
struct procent *ptnew; /* Ptr to table entry for new process */
/* If rescheduling is deferred, record attempt and return */
if (Defer.ndefers > 0) {
Defer.attempt = TRUE;
return;
}
/* Point to process table entry for the current (old) process */
uint32 addToTotalTime =0;
/* Point to process table entry for the current (old) process */
ptold = &proctab[currpid];
//Update the total processing time for context switched out process
// Handle the case where the counter overflows then get the absolute value of difference
addToTotalTime = (currTime)-(ptold->prctxswintime);
ptold->prcpumsec = ptold->prcpumsec + addToTotalTime;
ptold = &proctab[currpid];
pri16 oldprio = ptold->prprio;
if (ptold->prstate == PR_CURR) {
// update the priority based on TS dispatch table values for active process's time quantum expiration scenario
pri16 oldprio = ptold->prprio;
int timegiven = tsdtab[oldprio].ts_quantum;
if(currpid != 0)
{
ptold->prprio = tsdtab[oldprio].ts_tqexp;
}
// cpu- intensive process
if(currproc_eligible()) // check eligibility of current process to get another quantum
{
ptold->prctxswintime = currTime;
return;
}
else
{
// current process will be switched out
// enqueu at correct location for when next time it may be selected
// by scheduler it will be at correct level on multi-level feedback queue.
ptold->prstate = PR_READY;
enqueue(currpid, queueArr[ptold->prprio]);
}
}
else if (ptold->prstate == PR_SLEEP)
{
// io- intensive process
// update the priority based on TS dispatch table values for sleep return
if(currpid != 0)
ptold->prprio = tsdtab[ptold->prprio].ts_slpret;
}
/* Force context switch to highest priority ready process */
currpid = multifeedbackDQ();
ptnew = &proctab[currpid];
ptnew->prstate = PR_CURR;
ptnew->prctxswintime = currTime;
preempt = tsdtab[ptnew->prprio].ts_quantum; /* Reset time slice for process */
ctxsw(&ptold->prstkptr, &ptnew->prstkptr);
// LAB 4Q3: Invoke the handleCallback
handleCallback();
/* Old process returns here when resumed */
return;
}
/*-----------------------------------------------------------------------
* resched -- reschedule processor to highest priority ready process
*
* Notes: Upon entry, currpid gives current process id.
* Proctab[currpid].pstate gives correct NEXT state for
* current process if other than PRREADY.
*------------------------------------------------------------------------
*/
int resched()
{
register struct pentry *optr; /* pointer to old process entry */
register struct pentry *nptr; /* pointer to new process entry */
int rand_num,temp_currpid,i;
/* no switch needed if current process priority higher than next*/
if(used_scheduler == RANDOMSCHED)
{
optr= &proctab[currpid];
}
else if(used_scheduler == LINUXSCHED)
{
optr= &proctab[currpid];
}
else
{
if ( ( (optr= &proctab[currpid])->pstate == PRCURR) &&
(lastkey(rdytail)<optr->pprio))
{
return(OK);
}
}
/* force context switch */
if (optr->pstate == PRCURR)
{
optr->pstate = PRREADY;
optr->arrival_time = ctr1000;
if(preempt >= 0)
optr->quantum_left = preempt;
insert(currpid,rdyhead,optr->pprio);
}
/* remove highest priority process at end of ready list */
if(used_scheduler != LINUXSCHED)
{
execution_time[currpid]+=(QUANTUM-preempt);
}
else
execution_time[currpid]+= (proctab[currpid].quantum_left -preempt);
//kprintf("\nPreempt: %d",preempt);
if(used_scheduler == RANDOMSCHED)
{
if(q[rdyhead].qnext == rdytail)
return(OK);
do
{
rand_num = rand()%100;
// kprintf("Random Number: %d",rand_num);
if(rand_num >=80)
temp_currpid = random_getpid(1);
else if(rand_num <80 && rand_num >=50)
temp_currpid = random_getpid(2);
else
temp_currpid = random_getpid(3);
}while(temp_currpid == -1);
currpid = temp_currpid;
nptr = &proctab[currpid];
dequeue(currpid);
//kprintf("\n Current PID : %d",currpid);
}
else if(used_scheduler == LINUXSCHED)
{
temp_currpid = linux_getpid();
if(temp_currpid == -1)
{
new_epoch();
temp_currpid = linux_getpid();
if(temp_currpid == -1)
{
temp_currpid=0;;
}
}
currpid = temp_currpid;
nptr = &proctab[currpid];
dequeue(currpid);
}
else
{
nptr = &proctab[ (currpid = getlast(rdytail)) ];
}
nptr->pstate = PRCURR; /* mark it currently running */
#ifdef RTCLOCK
if(used_scheduler != LINUXSCHED)
preempt = QUANTUM; /* reset preemption counter */
else
{ preempt = proctab[currpid].quantum_left;
}
#endif
ctxsw((int)&optr->pesp, (int)optr->pirmask, (int)&nptr->pesp, (int)nptr->pirmask);
/* The OLD process returns here when resumed. */
return OK;
}