Pid_t OSSim::contextSwitch(CPU_t cpu, Pid_t nPid)
{
// This is the process we displaced to run the target process
Pid_t oldPid=-1;
ProcessId *newProc = ProcessId::getProcessId(nPid);
I(newProc);
GProcessor *newCore=cpus.getProcessor(cpu);
I(newCore);
// Get the cpu where the target process is already running
CPU_t runCpu=(newProc->getState()==RunningState)?newProc->getCPU():-1;
// If already running on the target processor, do nothing
if(runCpu==cpu)
return -1;
// If target core has no available flows, make one
if(!newCore->availableFlows()) {
oldPid=newCore->findVictimPid();
ProcessId *oldProc=ProcessId::getProcessId(oldPid);
cpus.switchOut(cpu, oldProc);
}
// Is the target process already running on another cpu?
if(runCpu!=-1) {
// Get another process to run on original cpu
ProcessId *repProc=ProcessId::queueGet(runCpu);
// Get the target process out of old core
cpus.switchOut(runCpu, newProc);
// Get the replacement process (if any) into the old core
if(repProc)
cpus.switchIn(runCpu,repProc);
// Get the target process in the target cpu
cpus.switchIn(cpu, newProc);
} else {
// If new process not ready, make it ready
if(newProc->getState()!=ReadyState) {
// Make it prefer the target cpu
newProc->setCPU(cpu);
// Make it ready
newProc->setState(InvalidState);
cpus.makeRunnable(newProc);
// The target cpu is prefered by the target process, and
// the target cpu has available flows. Thus, the target
// process should be now running on the target cpu
I(newProc->getCPU()==cpu);
I(newProc->getState()==RunningState);
} else {
// The new process is already ready, just switch it in
cpus.switchIn(cpu,newProc);
}
}
return oldPid;
}
int32_t OSSim::eventYield(Pid_t curPid, Pid_t yieldPid)
{
// LOG("OSSim::yield(%d,%d)", curPid, yieldPid);
ProcessId *curProc=ProcessId::getProcessId(curPid);
// The current process should be running
I(curProc->getState()==RunningState);
// get the CPU where the current process is running
CPU_t cpu=curProc->getCPU();
// Get the ProcessId of the new process
ProcessId *yieldProc;
if(yieldPid<0) {
// No specific new process, get next ready process
yieldProc=ProcessId::queueGet(cpu);
} else {
// Specific ready process, get its ProcessId
yieldProc=ProcessId::getProcessId(yieldPid);
// there should be such a process
if(!yieldProc) {
LOG("OSSim::yield(%d) to non existing process???", yieldPid);
return 0;
}
}
// Do nothing if no process to yield to
if(!yieldProc)
return 1;
// Do nothing if the new process already running
if(yieldProc->getState()==RunningState)
return 1;
// The new process should not be suspended
if(yieldProc->getState()==SuspendedState) {
LOG("OSSim::yield(%d) to a suspended process???", yieldPid);
return 0;
}
// The new process should not be pinned to a other processor
if(yieldProc->isPinned()&&(yieldProc->getCPU()!=cpu)) {
LOG("OSSim::yield(%d) to a NOMIGRABLE process in another CPU", yieldPid);
return 0;
}
// Remove current process from the processor
cpus.switchOut(cpu,curProc);
// Put the new process on that processor
cpus.switchIn(cpu,yieldProc);
return 1;
}
void OSSim::setPriority(Pid_t pid, int32_t newPrio)
{
ProcessId *proc = ProcessId::getProcessId(pid);
I(proc);
int32_t oldPrio=proc->getPriority();
if(newPrio==oldPrio)
return;
// Set the new priority of the process
ProcessId *otherProc=proc->setPriority(newPrio);
if(newPrio>oldPrio) {
// Priority is better now, check if still running
if(proc->getState()==RunningState) {
// Is there a process we need to swap with
if(otherProc) {
// Get the cpu where the demoted process is running
CPU_t cpu=proc->getCPU();
// Switch the demoted process out
cpus.switchOut(cpu,proc);
// Switch the new process in
cpus.switchIn(cpu,otherProc);
}
}
} else {
// Priority is worse now, check if ready but not already running
if(proc->getState()==ReadyState) {
// Is there a process we need to swap with
if(otherProc) {
// Get the cpu where the other process is running
CPU_t cpu=otherProc->getCPU();
// Switch the victim process out
cpus.switchOut(cpu,otherProc);
// Switch the promoted process in
cpus.switchIn(cpu,proc);
}
}
}
}
