// 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;
}
int
cpunum(void)
{
// Cannot call cpu when interrupts are enabled:
// result not guaranteed to last long enough to be used!
// Would prefer to panic but even printing is chancy here:
// almost everything, including cprintf and panic, calls cpu,
// often indirectly through acquire and release.
if(readeflags()&FL_IF){
static int n;
if(n++ == 0)
cprintf("cpu called from %x with interrupts enabled\n",
__builtin_return_address(0));
}
if(lapic)
return lapic[ID]>>24;
return 0;
}
// Enter scheduler. Must hold only ptable.lock
// and have changed proc->state.
void
sched(void)
{
int intena;
if(!holding(&ptable.lock))
panic("sched ptable.lock");
if(cpu->ncli != 1){
cprintf("current proc %d\n cpu->ncli %d\n",proc->pid,cpu->ncli);
panic("sched locks");
}
if(proc->state == RUNNING)
panic("sched running");
if(readeflags()&FL_IF)
panic("sched interruptible");
intena = cpu->intena;
swtch(&proc->context, cpu->scheduler);
cpu->intena = intena;
}
void next_task()
{
uint8_t is_enabled = readeflags() & 0x200;
cli();
if (task_count <= 1)
{
return;
}
task_t *previous_task = current_task;
current_task = current_task->next;
switch_task(&(previous_task->regs), current_task->regs);
if(is_enabled)
{
sti();
}
}
//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;
for(;;){
// Enable interrupts on this processor.
sti();
// Loop over process table looking for process to run.
acquire(&ptable.lock);
#ifndef __ORIGINAL_SCHED__
p = pdequeue();
if(p){
#else
for(p = ptable.proc; p < &ptable.proc[NPROC]; p++){
if(p->state != RUNNABLE)
continue;
#endif
// For debug, checking the scheduled process priority
cprintf("cpu %d get process %s, process prio = %d\n",cpunum(),p->name,p->priority);
// Switch to chosen process. It is the process's job
// to release ptable.lock and then reacquire it
// before jumping back to us.
proc = p;
switchuvm(p);
p->state = RUNNING;
swtch(&cpu->scheduler, proc->context);
switchkvm();
// Process is done running for now.
// It should have changed its p->state before coming back.
proc = 0;
}
release(&ptable.lock);
}
}
// Enter scheduler. Must hold only ptable.lock
// and have changed proc->state.
void
sched(void)
{
int intena;
if(!holding(&ptable.lock))
panic("sched ptable.lock");
if(cpu->ncli != 1)
panic("sched locks");
if(proc->state == RUNNING)
panic("sched running");
if(readeflags()&FL_IF)
panic("sched interruptible");
intena = cpu->intena;
swtch(&proc->context, cpu->scheduler);
cpu->intena = intena;
}
