* Copyright 2008 Bernie Innocenti <bernie@codewiz.org>
* -->
*
- * \brief Simple realtime multitasking scheduler.
- * Context switching is only done cooperatively.
+ * \brief Simple preemptive multitasking scheduler.
*
* \version $Id: proc.c 1616 2008-08-10 19:41:26Z bernie $
* \author Bernie Innocenti <bernie@codewiz.org>
#include "proc.h"
#include <kern/irq.h>
+#include <kern/monitor.h>
#include <cpu/frame.h> // CPU_IDLE
#include <drv/timer.h>
#include <cfg/module.h>
-/*
- * The time sharing scheduler forces a task switch when the current
- * process has exhausted its quantum.
- */
-uint16_t Quantum;
Timer preempt_timer;
void proc_preempt(void)
{
- TRACE;
+ IRQ_DISABLE;
- ATOMIC(LIST_ASSERT_VALID(&ProcReadyList));
+ LIST_ASSERT_VALID(&ProcReadyList);
+ CurrentProcess = (struct Process *)list_remHead(&ProcReadyList);
+ LIST_ASSERT_VALID(&ProcReadyList);
+ ASSERT2(CurrentProcess, "no idle proc?");
- TRACEMSG("hello1");
- IRQ_DISABLE;
- /* Poll on the ready queue for the first ready process */
- while (!(CurrentProcess = (struct Process *)list_remHead(&ProcReadyList)))
- {
- //TRACEMSG("hello2");
- /*
- * Make sure we physically reenable interrupts here, no matter what
- * the current task status is. This is important because if we
- * are idle-spinning, we must allow interrupts, otherwise no
- * process will ever wake up.
- *
- * During idle-spinning, an interrupt can occur and it may
- * modify \p ProcReadyList. To ensure that compiler reload this
- * variable every while cycle we call CPU_MEMORY_BARRIER.
- * The memory barrier ensure that all variables used in this context
- * are reloaded.
- */
- IRQ_ENABLE;
- //FIXME: calls Qt stuff from sighandler! CPU_IDLE;
- MEMORY_BARRIER;
- IRQ_DISABLE;
- //TRACEMSG("hello3");
- }
IRQ_ENABLE;
- TRACEMSG("hello4");
+
+ TRACEMSG("new proc: %p:%s", CurrentProcess, CurrentProcess ? CurrentProcess->monitor.name : "---");
+ monitor_report();
}
void proc_preempt_timer(UNUSED_ARG(void *, param))
{
IRQ_DISABLE;
- if (CurrentProcess)
+/*
+ if (!CurrentProcess->forbid_cnt)
{
TRACEMSG("preempting %p:%s", CurrentProcess, CurrentProcess->monitor.name);
+ LIST_ASSERT_VALID(&ProcReadyList);
SCHED_ENQUEUE(CurrentProcess);
- IRQ_ENABLE;
proc_preempt();
}
+*/
IRQ_ENABLE;
timer_setDelay(&preempt_timer, CONFIG_KERN_QUANTUM);
void proc_yield(void)
{
- ATOMIC(SCHED_ENQUEUE(CurrentProcess));
+ TRACE;
+ ASSERT_IRQ_ENABLED();
+ IRQ_DISABLE;
+ SCHED_ENQUEUE(CurrentProcess);
+ LIST_ASSERT_VALID(&ProcReadyList);
proc_schedule();
+ IRQ_ENABLE;
}
void proc_entry(void (*user_entry)(void))
proc_exit();
}
+
+static cpustack_t idle_stack[CONFIG_PROC_DEFSTACKSIZE / sizeof(cpustack_t)];
+
+/*
+ * The idle process
+ *
+ * This process never dies and never sleeps. It's also quite apathic
+ * and a bit antisocial.
+ *
+ * Having an idle process costs some stack space, but simplifies the
+ * interrupt-driven preemption logic because there is always a user
+ * context to which we can return.
+ */
+static NORETURN void idle(void)
+{
+ for (;;)
+ {
+ TRACE;
+ monitor_report();
+ proc_yield(); // FIXME: CPU_IDLE
+ }
+}
+
void preempt_init(void)
{
MOD_CHECK(irq);
timer_setSoftint(&preempt_timer, proc_preempt_timer, NULL);
timer_setDelay(&preempt_timer, CONFIG_KERN_QUANTUM);
timer_add(&preempt_timer);
+
+ proc_new(idle, NULL, sizeof(idle_stack), idle_stack);
}