Initial Spring 2016 commit.

2015-12-23 00:50:04 +00:00
commit cafa9f5690
732 changed files with 92195 additions and 0 deletions
--- a/kern/thread/clock.c
+++ b/kern/thread/clock.c
@@ -0,0 +1,121 @@
+/*
+ * Copyright (c) 2000, 2001, 2002, 2003, 2004, 2005, 2008, 2009
+ *	The President and Fellows of Harvard College.
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ * 3. Neither the name of the University nor the names of its contributors
+ *    may be used to endorse or promote products derived from this software
+ *    without specific prior written permission.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE UNIVERSITY AND CONTRIBUTORS ``AS IS'' AND
+ * ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
+ * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
+ * ARE DISCLAIMED.  IN NO EVENT SHALL THE UNIVERSITY OR CONTRIBUTORS BE LIABLE
+ * FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
+ * DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
+ * OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
+ * HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
+ * LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
+ * OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
+ * SUCH DAMAGE.
+ */
+
+#include <types.h>
+#include <lib.h>
+#include <cpu.h>
+#include <wchan.h>
+#include <clock.h>
+#include <thread.h>
+#include <current.h>
+
+/*
+ * Time handling.
+ *
+ * This is pretty primitive. A real kernel will typically have some
+ * kind of support for scheduling callbacks to happen at specific
+ * points in the future, usually with more resolution than one second.
+ *
+ * A real kernel also has to maintain the time of day; in OS/161 we
+ * skimp on that because we have a known-good hardware clock.
+ */
+
+/*
+ * Timing constants. These should be tuned along with any work done on
+ * the scheduler.
+ */
+#define SCHEDULE_HARDCLOCKS	4	/* Reschedule every 4 hardclocks. */
+#define MIGRATE_HARDCLOCKS	16	/* Migrate every 16 hardclocks. */
+
+/*
+ * Once a second, everything waiting on lbolt is awakened by CPU 0.
+ */
+static struct wchan *lbolt;
+static struct spinlock lbolt_lock;
+
+/*
+ * Setup.
+ */
+void
+hardclock_bootstrap(void)
+{
+	spinlock_init(&lbolt_lock);
+	lbolt = wchan_create("lbolt");
+	if (lbolt == NULL) {
+		panic("Couldn't create lbolt\n");
+	}
+}
+
+/*
+ * This is called once per second, on one processor, by the timer
+ * code.
+ */
+void
+timerclock(void)
+{
+	/* Just broadcast on lbolt */
+	spinlock_acquire(&lbolt_lock);
+	wchan_wakeall(lbolt, &lbolt_lock);
+	spinlock_release(&lbolt_lock);
+}
+
+/*
+ * This is called HZ times a second (on each processor) by the timer
+ * code.
+ */
+void
+hardclock(void)
+{
+	/*
+	 * Collect statistics here as desired.
+	 */
+
+	curcpu->c_hardclocks++;
+	if ((curcpu->c_hardclocks % MIGRATE_HARDCLOCKS) == 0) {
+		thread_consider_migration();
+	}
+	if ((curcpu->c_hardclocks % SCHEDULE_HARDCLOCKS) == 0) {
+		schedule();
+	}
+	thread_yield();
+}
+
+/*
+ * Suspend execution for n seconds.
+ */
+void
+clocksleep(int num_secs)
+{
+	spinlock_acquire(&lbolt_lock);
+	while (num_secs > 0) {
+		wchan_sleep(lbolt, &lbolt_lock);
+		num_secs--;
+	}
+	spinlock_release(&lbolt_lock);
+}