Initial source

1 files changed, 225 insertions, 0 deletions

diff --git a/kern/priority.c b/kern/priority.c
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+/*
+ * Mach Operating System
+ * Copyright (c) 1991,1990,1989,1988,1987 Carnegie Mellon University.
+ * Copyright (c) 1993,1994 The University of Utah and
+ * the Computer Systems Laboratory (CSL).
+ * All rights reserved.
+ *
+ * Permission to use, copy, modify and distribute this software and its
+ * documentation is hereby granted, provided that both the copyright
+ * notice and this permission notice appear in all copies of the
+ * software, derivative works or modified versions, and any portions
+ * thereof, and that both notices appear in supporting documentation.
+ *
+ * CARNEGIE MELLON, THE UNIVERSITY OF UTAH AND CSL ALLOW FREE USE OF
+ * THIS SOFTWARE IN ITS "AS IS" CONDITION, AND DISCLAIM ANY LIABILITY
+ * OF ANY KIND FOR ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF
+ * THIS SOFTWARE.
+ *
+ * Carnegie Mellon requests users of this software to return to
+ *
+ *  Software Distribution Coordinator  or  Software.Distribution@CS.CMU.EDU
+ *  School of Computer Science
+ *  Carnegie Mellon University
+ *  Pittsburgh PA 15213-3890
+ *
+ * any improvements or extensions that they make and grant Carnegie Mellon
+ * the rights to redistribute these changes.
+ */
+/*
+ *	File:	clock_prim.c
+ *	Author:	Avadis Tevanian, Jr.
+ *	Date:	1986
+ *
+ *	Clock primitives.
+ */
+
+#include <cpus.h>
+
+#include <mach/boolean.h>
+#include <mach/kern_return.h>
+#include <mach/machine.h>
+#include <kern/host.h>
+#include <kern/mach_param.h>
+#include <kern/sched.h>
+#include <kern/thread.h>
+#include <kern/processor.h>
+#include <kern/timer.h>
+#include <kern/time_out.h>
+#include <kern/time_stamp.h>
+#include <machine/machspl.h>
+
+
+
+/*
+ *	USAGE_THRESHOLD is the amount by which usage must change to
+ *	cause a priority shift that moves a thread between run queues.
+ */
+
+#ifdef	PRI_SHIFT_2
+#if	PRI_SHIFT_2 > 0
+#define	USAGE_THRESHOLD (((1 << PRI_SHIFT) + (1 << PRI_SHIFT_2)) << (2 + SCHED_SHIFT))
+#else	/* PRI_SHIFT_2 > 0 */
+#define	USAGE_THRESHOLD (((1 << PRI_SHIFT) - (1 << -(PRI_SHIFT_2))) << (2 + SCHED_SHIFT))
+#endif	/* PRI_SHIFT_2 > 0 */
+#else	/* PRI_SHIFT_2 */
+#define USAGE_THRESHOLD	(1 << (PRI_SHIFT + 2 + SCHED_SHIFT))
+#endif	/* PRI_SHIFT_2 */
+
+/*
+ *	thread_quantum_update:
+ *
+ *	Recalculate the quantum and priority for a thread.
+ *	The number of ticks that has elapsed since we were last called
+ *	is passed as "nticks."
+ *
+ *	Called only from clock_interrupt().
+ */
+
+void thread_quantum_update(mycpu, thread, nticks, state)
+	register int		mycpu;
+	register thread_t	thread;
+	int			nticks;
+	int			state;
+{
+	register int			quantum;
+	register processor_t		myprocessor;
+#if	NCPUS > 1
+	register processor_set_t	pset;
+#endif
+	spl_t				s;
+
+	myprocessor = cpu_to_processor(mycpu);
+#if	NCPUS > 1
+	pset = myprocessor->processor_set;
+	if (pset == 0) {
+	    /*
+	     * Processor is being reassigned.
+	     * Should rewrite processor assignment code to
+	     * block clock interrupts.
+	     */
+	    return;
+	}
+#endif	/* NCPUS > 1 */
+
+	/*
+	 *	Account for thread's utilization of these ticks.
+	 *	This assumes that there is *always* a current thread.
+	 *	When the processor is idle, it should be the idle thread.
+	 */
+
+	/*
+	 *	Update set_quantum and calculate the current quantum.
+	 */
+#if	NCPUS > 1
+	pset->set_quantum = pset->machine_quantum[
+		((pset->runq.count > pset->processor_count) ?
+		  pset->processor_count : pset->runq.count)];
+
+	if (myprocessor->runq.count != 0)
+		quantum = min_quantum;
+	else
+		quantum = pset->set_quantum;
+#else	/* NCPUS > 1 */
+	quantum = min_quantum;
+	default_pset.set_quantum = quantum;
+#endif	/* NCPUS > 1 */
+		
+	/*
+	 *	Now recompute the priority of the thread if appropriate.
+	 */
+
+	if (state != CPU_STATE_IDLE) {
+		myprocessor->quantum -= nticks;
+#if	NCPUS > 1
+		/*
+		 *	Runtime quantum adjustment.  Use quantum_adj_index
+		 *	to avoid synchronizing quantum expirations.
+		 */
+		if ((quantum != myprocessor->last_quantum) &&
+		    (pset->processor_count > 1)) {
+			myprocessor->last_quantum = quantum;
+			simple_lock(&pset->quantum_adj_lock);
+			quantum = min_quantum + (pset->quantum_adj_index *
+				(quantum - min_quantum)) / 
+					(pset->processor_count - 1);
+			if (++(pset->quantum_adj_index) >=
+			    pset->processor_count)
+				pset->quantum_adj_index = 0;
+			simple_unlock(&pset->quantum_adj_lock);
+		}
+#endif	/* NCPUS > 1 */
+		if (myprocessor->quantum <= 0) {
+			s = splsched();
+			thread_lock(thread);
+			if (thread->sched_stamp != sched_tick) {
+				update_priority(thread);
+			}
+			else {
+			    if (
+#if	MACH_FIXPRI
+				(thread->policy == POLICY_TIMESHARE) &&
+#endif	/* MACH_FIXPRI */
+				(thread->depress_priority < 0)) {
+				    thread_timer_delta(thread);
+				    thread->sched_usage +=
+					thread->sched_delta;
+				    thread->sched_delta = 0;
+				    compute_my_priority(thread);
+			    }
+			}
+			thread_unlock(thread);
+			(void) splx(s);
+			/*
+			 *	This quantum is up, give this thread another.
+			 */
+			myprocessor->first_quantum = FALSE;
+#if	MACH_FIXPRI
+			if (thread->policy == POLICY_TIMESHARE) {
+#endif	/* MACH_FIXPRI */
+				myprocessor->quantum += quantum;
+#if	MACH_FIXPRI
+			}
+			else {
+				/*
+				 *    Fixed priority has per-thread quantum.
+				 *    
+				 */
+				myprocessor->quantum += thread->sched_data;
+			}
+#endif	/* MACH_FIXPRI */
+		}
+		/*
+		 *	Recompute priority if appropriate.
+		 */
+		else {
+		    s = splsched();
+		    thread_lock(thread);
+		    if (thread->sched_stamp != sched_tick) {
+			update_priority(thread);
+		    }
+		    else {
+			if (
+#if	MACH_FIXPRI
+			    (thread->policy == POLICY_TIMESHARE) &&
+#endif	/* MACH_FIXPRI */
+			    (thread->depress_priority < 0)) {
+				thread_timer_delta(thread);
+				if (thread->sched_delta >= USAGE_THRESHOLD) {
+				    thread->sched_usage +=
+					thread->sched_delta;
+				    thread->sched_delta = 0;
+				    compute_my_priority(thread);
+				}
+			}
+		    }
+		    thread_unlock(thread);
+		    (void) splx(s);
+		}
+		/*
+		 * Check for and schedule ast if needed.
+		 */
+		ast_check();
+	}
+}
+