* invalidate any other reasons why the executable file might be covered by
* the GNU General Public License.
*
- * Copyright 2001, 2004 Develer S.r.l. (http://www.develer.com/)
- * Copyright 1999, 2000, 2001, 2008 Bernie Innocenti <bernie@codewiz.org>
+ * 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>
- * \author Stefano Fedrigo <aleph@develer.com>
*/
#include "proc_p.h"
#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>
-#include <unistd.h> // XXX alarm()
-/*
- * The time sharing scheduler forces a task switch when the current
- * process has exhausted its quantum.
- */
-uint16_t Quantum;
+Timer preempt_timer;
/**
* Disable preemptive task switching.
--CurrentProcess->forbid_cnt;
}
-static void (*irq_handlers[100])(void); // FIXME
-
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?");
- IRQ_DISABLE;
- /* Poll on the ready queue for the first ready process */
- while (!(CurrentProcess = (struct Process *)list_remHead(&ProcReadyList)))
- {
- /*
- * 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;
- CPU_IDLE;
- MEMORY_BARRIER;
- IRQ_DISABLE;
- }
IRQ_ENABLE;
+
+ TRACEMSG("new proc: %p:%s", CurrentProcess, CurrentProcess ? CurrentProcess->monitor.name : "---");
+ monitor_report();
}
-void proc_preempt_timer(void)
+void proc_preempt_timer(UNUSED_ARG(void *, param))
{
- // TODO: check Quantum
+ IRQ_DISABLE;
+/*
+ if (!CurrentProcess->forbid_cnt)
+ {
+ TRACEMSG("preempting %p:%s", CurrentProcess, CurrentProcess->monitor.name);
+ LIST_ASSERT_VALID(&ProcReadyList);
+ SCHED_ENQUEUE(CurrentProcess);
+ proc_preempt();
+ }
+*/
+ IRQ_ENABLE;
- alarm(1);
- ATOMIC(SCHED_ENQUEUE(CurrentProcess));
- proc_schedule();
+ timer_setDelay(&preempt_timer, CONFIG_KERN_QUANTUM);
+ timer_add(&preempt_timer);
}
void proc_schedule(void)
{
+ TRACE;
+
+ // Will invoke proc_preempt() in interrupt context
kill(0, SIGUSR1);
}
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;
}
-/* signal handler */
-void irq_entry(int signum)
+void proc_entry(void (*user_entry)(void))
{
- Process *old_process;
-
- TRACEMSG("storing %p:%s", CurrentProcess, CurrentProcess->monitor.name);
- CurrentProcess->leaving = false;
- getcontext(&CurrentProcess->context);
- /* We get here in two ways: directly, and after setcontext() below */
-
- if (CurrentProcess->leaving)
- {
- TRACEMSG("leaving to %p:%s", CurrentProcess, CurrentProcess->monitor.name);
- return;
- }
+ user_entry();
+ proc_exit();
+}
- old_process = CurrentProcess;
- irq_handlers[signum]();
+static cpustack_t idle_stack[CONFIG_PROC_DEFSTACKSIZE / sizeof(cpustack_t)];
- if (old_process != CurrentProcess)
+/*
+ * 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 (;;)
{
- TRACEMSG("launching %p:%s", CurrentProcess, CurrentProcess->monitor.name);
- CurrentProcess->leaving = true;
- setcontext(&CurrentProcess->context);
- /* not reached */
+ TRACE;
+ monitor_report();
+ proc_yield(); // FIXME: CPU_IDLE
}
-
- TRACEMSG("keeping %p:%s", CurrentProcess, CurrentProcess->monitor.name);
}
void preempt_init(void)
{
- struct sigaction act;
- act.sa_handler = irq_entry;
- sigemptyset(&act.sa_mask);
- sigaddset(&act.sa_mask, SIGUSR1);
- sigaddset(&act.sa_mask, SIGALRM);
- act.sa_flags = SA_RESTART; /* | SA_SIGINFO; */
-
- irq_handlers[SIGUSR1] = proc_preempt;
- irq_handlers[SIGALRM] = proc_preempt_timer;
- sigaction(SIGUSR1, &act, NULL);
- sigaction(SIGALRM, &act, NULL);
-
- alarm(1);
+ MOD_CHECK(irq);
+ MOD_CHECK(timer);
+
+ irq_register(SIGUSR1, proc_preempt);
+
+ 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);
}