socsvn commit: r222332 - in soc2011/rudot: . kern

rudot at FreeBSD.org rudot at FreeBSD.org
Tue May 24 08:51:10 UTC 2011


Author: rudot
Date: Tue May 24 08:51:08 2011
New Revision: 222332
URL: http://svnweb.FreeBSD.org/socsvn/?view=rev&rev=222332

Log:
  Original 4.4BSD scheduler as a starting point

Added:
  soc2011/rudot/kern/
  soc2011/rudot/kern/sched_4bsd.c
Deleted:
  soc2011/rudot/test.c

Added: soc2011/rudot/kern/sched_4bsd.c
==============================================================================
--- /dev/null	00:00:00 1970	(empty, because file is newly added)
+++ soc2011/rudot/kern/sched_4bsd.c	Tue May 24 08:51:08 2011	(r222332)
@@ -0,0 +1,1679 @@
+/*-
+ * Copyright (c) 1982, 1986, 1990, 1991, 1993
+ *	The Regents of the University of California.  All rights reserved.
+ * (c) UNIX System Laboratories, Inc.
+ * All or some portions of this file are derived from material licensed
+ * to the University of California by American Telephone and Telegraph
+ * Co. or Unix System Laboratories, Inc. and are reproduced herein with
+ * the permission of UNIX System Laboratories, Inc.
+ *
+ * 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.
+ * 4. 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 REGENTS 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 REGENTS 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 <sys/cdefs.h>
+__FBSDID("$FreeBSD: src/sys/kern/sched_4bsd.c,v 1.131.2.7.2.1 2010/12/21 17:09:25 kensmith Exp $");
+
+#include "opt_hwpmc_hooks.h"
+#include "opt_sched.h"
+#include "opt_kdtrace.h"
+
+#include <sys/param.h>
+#include <sys/systm.h>
+#include <sys/cpuset.h>
+#include <sys/kernel.h>
+#include <sys/ktr.h>
+#include <sys/lock.h>
+#include <sys/kthread.h>
+#include <sys/mutex.h>
+#include <sys/proc.h>
+#include <sys/resourcevar.h>
+#include <sys/sched.h>
+#include <sys/smp.h>
+#include <sys/sysctl.h>
+#include <sys/sx.h>
+#include <sys/turnstile.h>
+#include <sys/umtx.h>
+#include <machine/pcb.h>
+#include <machine/smp.h>
+
+#ifdef HWPMC_HOOKS
+#include <sys/pmckern.h>
+#endif
+
+#ifdef KDTRACE_HOOKS
+#include <sys/dtrace_bsd.h>
+int				dtrace_vtime_active;
+dtrace_vtime_switch_func_t	dtrace_vtime_switch_func;
+#endif
+
+/*
+ * INVERSE_ESTCPU_WEIGHT is only suitable for statclock() frequencies in
+ * the range 100-256 Hz (approximately).
+ */
+#define	ESTCPULIM(e) \
+    min((e), INVERSE_ESTCPU_WEIGHT * (NICE_WEIGHT * (PRIO_MAX - PRIO_MIN) - \
+    RQ_PPQ) + INVERSE_ESTCPU_WEIGHT - 1)
+#ifdef SMP
+#define	INVERSE_ESTCPU_WEIGHT	(8 * smp_cpus)
+#else
+#define	INVERSE_ESTCPU_WEIGHT	8	/* 1 / (priorities per estcpu level). */
+#endif
+#define	NICE_WEIGHT		1	/* Priorities per nice level. */
+
+#define	TS_NAME_LEN (MAXCOMLEN + sizeof(" td ") + sizeof(__XSTRING(UINT_MAX)))
+
+/*
+ * The schedulable entity that runs a context.
+ * This is  an extension to the thread structure and is tailored to
+ * the requirements of this scheduler
+ */
+struct td_sched {
+	fixpt_t		ts_pctcpu;	/* (j) %cpu during p_swtime. */
+	int		ts_cpticks;	/* (j) Ticks of cpu time. */
+	int		ts_slptime;	/* (j) Seconds !RUNNING. */
+	int		ts_flags;
+	struct runq	*ts_runq;	/* runq the thread is currently on */
+#ifdef KTR
+	char		ts_name[TS_NAME_LEN];
+#endif
+};
+
+/* flags kept in td_flags */
+#define TDF_DIDRUN	TDF_SCHED0	/* thread actually ran. */
+#define TDF_BOUND	TDF_SCHED1	/* Bound to one CPU. */
+
+/* flags kept in ts_flags */
+#define	TSF_AFFINITY	0x0001		/* Has a non-"full" CPU set. */
+
+#define SKE_RUNQ_PCPU(ts)						\
+    ((ts)->ts_runq != 0 && (ts)->ts_runq != &runq)
+
+#define	THREAD_CAN_SCHED(td, cpu)	\
+    CPU_ISSET((cpu), &(td)->td_cpuset->cs_mask)
+
+static struct td_sched td_sched0;
+struct mtx sched_lock;
+
+static int	sched_tdcnt;	/* Total runnable threads in the system. */
+static int	sched_quantum;	/* Roundrobin scheduling quantum in ticks. */
+#define	SCHED_QUANTUM	(hz / 10)	/* Default sched quantum */
+
+static void	setup_runqs(void);
+static void	schedcpu(void);
+static void	schedcpu_thread(void);
+static void	sched_priority(struct thread *td, u_char prio);
+static void	sched_setup(void *dummy);
+static void	maybe_resched(struct thread *td);
+static void	updatepri(struct thread *td);
+static void	resetpriority(struct thread *td);
+static void	resetpriority_thread(struct thread *td);
+#ifdef SMP
+static int	sched_pickcpu(struct thread *td);
+static int	forward_wakeup(int cpunum);
+static void	kick_other_cpu(int pri, int cpuid);
+#endif
+
+static struct kproc_desc sched_kp = {
+        "schedcpu",
+        schedcpu_thread,
+        NULL
+};
+SYSINIT(schedcpu, SI_SUB_RUN_SCHEDULER, SI_ORDER_FIRST, kproc_start,
+    &sched_kp);
+SYSINIT(sched_setup, SI_SUB_RUN_QUEUE, SI_ORDER_FIRST, sched_setup, NULL);
+
+/*
+ * Global run queue.
+ */
+static struct runq runq;
+
+#ifdef SMP
+/*
+ * Per-CPU run queues
+ */
+static struct runq runq_pcpu[MAXCPU];
+long runq_length[MAXCPU];
+#endif
+
+static void
+setup_runqs(void)
+{
+#ifdef SMP
+	int i;
+
+	for (i = 0; i < MAXCPU; ++i)
+		runq_init(&runq_pcpu[i]);
+#endif
+
+	runq_init(&runq);
+}
+
+static int
+sysctl_kern_quantum(SYSCTL_HANDLER_ARGS)
+{
+	int error, new_val;
+
+	new_val = sched_quantum * tick;
+	error = sysctl_handle_int(oidp, &new_val, 0, req);
+        if (error != 0 || req->newptr == NULL)
+		return (error);
+	if (new_val < tick)
+		return (EINVAL);
+	sched_quantum = new_val / tick;
+	hogticks = 2 * sched_quantum;
+	return (0);
+}
+
+SYSCTL_NODE(_kern, OID_AUTO, sched, CTLFLAG_RD, 0, "Scheduler");
+
+SYSCTL_STRING(_kern_sched, OID_AUTO, name, CTLFLAG_RD, "4BSD", 0,
+    "Scheduler name");
+
+SYSCTL_PROC(_kern_sched, OID_AUTO, quantum, CTLTYPE_INT | CTLFLAG_RW,
+    0, sizeof sched_quantum, sysctl_kern_quantum, "I",
+    "Roundrobin scheduling quantum in microseconds");
+
+#ifdef SMP
+/* Enable forwarding of wakeups to all other cpus */
+SYSCTL_NODE(_kern_sched, OID_AUTO, ipiwakeup, CTLFLAG_RD, NULL, "Kernel SMP");
+
+static int runq_fuzz = 1;
+SYSCTL_INT(_kern_sched, OID_AUTO, runq_fuzz, CTLFLAG_RW, &runq_fuzz, 0, "");
+
+static int forward_wakeup_enabled = 1;
+SYSCTL_INT(_kern_sched_ipiwakeup, OID_AUTO, enabled, CTLFLAG_RW,
+	   &forward_wakeup_enabled, 0,
+	   "Forwarding of wakeup to idle CPUs");
+
+static int forward_wakeups_requested = 0;
+SYSCTL_INT(_kern_sched_ipiwakeup, OID_AUTO, requested, CTLFLAG_RD,
+	   &forward_wakeups_requested, 0,
+	   "Requests for Forwarding of wakeup to idle CPUs");
+
+static int forward_wakeups_delivered = 0;
+SYSCTL_INT(_kern_sched_ipiwakeup, OID_AUTO, delivered, CTLFLAG_RD,
+	   &forward_wakeups_delivered, 0,
+	   "Completed Forwarding of wakeup to idle CPUs");
+
+static int forward_wakeup_use_mask = 1;
+SYSCTL_INT(_kern_sched_ipiwakeup, OID_AUTO, usemask, CTLFLAG_RW,
+	   &forward_wakeup_use_mask, 0,
+	   "Use the mask of idle cpus");
+
+static int forward_wakeup_use_loop = 0;
+SYSCTL_INT(_kern_sched_ipiwakeup, OID_AUTO, useloop, CTLFLAG_RW,
+	   &forward_wakeup_use_loop, 0,
+	   "Use a loop to find idle cpus");
+
+static int forward_wakeup_use_single = 0;
+SYSCTL_INT(_kern_sched_ipiwakeup, OID_AUTO, onecpu, CTLFLAG_RW,
+	   &forward_wakeup_use_single, 0,
+	   "Only signal one idle cpu");
+
+static int forward_wakeup_use_htt = 0;
+SYSCTL_INT(_kern_sched_ipiwakeup, OID_AUTO, htt2, CTLFLAG_RW,
+	   &forward_wakeup_use_htt, 0,
+	   "account for htt");
+
+#endif
+#if 0
+static int sched_followon = 0;
+SYSCTL_INT(_kern_sched, OID_AUTO, followon, CTLFLAG_RW,
+	   &sched_followon, 0,
+	   "allow threads to share a quantum");
+#endif
+
+static __inline void
+sched_load_add(void)
+{
+
+	sched_tdcnt++;
+	KTR_COUNTER0(KTR_SCHED, "load", "global load", sched_tdcnt);
+}
+
+static __inline void
+sched_load_rem(void)
+{
+
+	sched_tdcnt--;
+	KTR_COUNTER0(KTR_SCHED, "load", "global load", sched_tdcnt);
+}
+/*
+ * Arrange to reschedule if necessary, taking the priorities and
+ * schedulers into account.
+ */
+static void
+maybe_resched(struct thread *td)
+{
+
+	THREAD_LOCK_ASSERT(td, MA_OWNED);
+	if (td->td_priority < curthread->td_priority)
+		curthread->td_flags |= TDF_NEEDRESCHED;
+}
+
+/*
+ * This function is called when a thread is about to be put on run queue
+ * because it has been made runnable or its priority has been adjusted.  It
+ * determines if the new thread should be immediately preempted to.  If so,
+ * it switches to it and eventually returns true.  If not, it returns false
+ * so that the caller may place the thread on an appropriate run queue.
+ */
+int
+maybe_preempt(struct thread *td)
+{
+#ifdef PREEMPTION
+	struct thread *ctd;
+	int cpri, pri;
+
+	/*
+	 * The new thread should not preempt the current thread if any of the
+	 * following conditions are true:
+	 *
+	 *  - The kernel is in the throes of crashing (panicstr).
+	 *  - The current thread has a higher (numerically lower) or
+	 *    equivalent priority.  Note that this prevents curthread from
+	 *    trying to preempt to itself.
+	 *  - It is too early in the boot for context switches (cold is set).
+	 *  - The current thread has an inhibitor set or is in the process of
+	 *    exiting.  In this case, the current thread is about to switch
+	 *    out anyways, so there's no point in preempting.  If we did,
+	 *    the current thread would not be properly resumed as well, so
+	 *    just avoid that whole landmine.
+	 *  - If the new thread's priority is not a realtime priority and
+	 *    the current thread's priority is not an idle priority and
+	 *    FULL_PREEMPTION is disabled.
+	 *
+	 * If all of these conditions are false, but the current thread is in
+	 * a nested critical section, then we have to defer the preemption
+	 * until we exit the critical section.  Otherwise, switch immediately
+	 * to the new thread.
+	 */
+	ctd = curthread;
+	THREAD_LOCK_ASSERT(td, MA_OWNED);
+	KASSERT((td->td_inhibitors == 0),
+			("maybe_preempt: trying to run inhibited thread"));
+	pri = td->td_priority;
+	cpri = ctd->td_priority;
+	if (panicstr != NULL || pri >= cpri || cold /* || dumping */ ||
+	    TD_IS_INHIBITED(ctd))
+		return (0);
+#ifndef FULL_PREEMPTION
+	if (pri > PRI_MAX_ITHD && cpri < PRI_MIN_IDLE)
+		return (0);
+#endif
+
+	if (ctd->td_critnest > 1) {
+		CTR1(KTR_PROC, "maybe_preempt: in critical section %d",
+		    ctd->td_critnest);
+		ctd->td_owepreempt = 1;
+		return (0);
+	}
+	/*
+	 * Thread is runnable but not yet put on system run queue.
+	 */
+	MPASS(ctd->td_lock == td->td_lock);
+	MPASS(TD_ON_RUNQ(td));
+	TD_SET_RUNNING(td);
+	CTR3(KTR_PROC, "preempting to thread %p (pid %d, %s)\n", td,
+	    td->td_proc->p_pid, td->td_name);
+	mi_switch(SW_INVOL | SW_PREEMPT | SWT_PREEMPT, td);
+	/*
+	 * td's lock pointer may have changed.  We have to return with it
+	 * locked.
+	 */
+	spinlock_enter();
+	thread_unlock(ctd);
+	thread_lock(td);
+	spinlock_exit();
+	return (1);
+#else
+	return (0);
+#endif
+}
+
+/*
+ * Constants for digital decay and forget:
+ *	90% of (td_estcpu) usage in 5 * loadav time
+ *	95% of (ts_pctcpu) usage in 60 seconds (load insensitive)
+ *          Note that, as ps(1) mentions, this can let percentages
+ *          total over 100% (I've seen 137.9% for 3 processes).
+ *
+ * Note that schedclock() updates td_estcpu and p_cpticks asynchronously.
+ *
+ * We wish to decay away 90% of td_estcpu in (5 * loadavg) seconds.
+ * That is, the system wants to compute a value of decay such
+ * that the following for loop:
+ * 	for (i = 0; i < (5 * loadavg); i++)
+ * 		td_estcpu *= decay;
+ * will compute
+ * 	td_estcpu *= 0.1;
+ * for all values of loadavg:
+ *
+ * Mathematically this loop can be expressed by saying:
+ * 	decay ** (5 * loadavg) ~= .1
+ *
+ * The system computes decay as:
+ * 	decay = (2 * loadavg) / (2 * loadavg + 1)
+ *
+ * We wish to prove that the system's computation of decay
+ * will always fulfill the equation:
+ * 	decay ** (5 * loadavg) ~= .1
+ *
+ * If we compute b as:
+ * 	b = 2 * loadavg
+ * then
+ * 	decay = b / (b + 1)
+ *
+ * We now need to prove two things:
+ *	1) Given factor ** (5 * loadavg) ~= .1, prove factor == b/(b+1)
+ *	2) Given b/(b+1) ** power ~= .1, prove power == (5 * loadavg)
+ *
+ * Facts:
+ *         For x close to zero, exp(x) =~ 1 + x, since
+ *              exp(x) = 0! + x**1/1! + x**2/2! + ... .
+ *              therefore exp(-1/b) =~ 1 - (1/b) = (b-1)/b.
+ *         For x close to zero, ln(1+x) =~ x, since
+ *              ln(1+x) = x - x**2/2 + x**3/3 - ...     -1 < x < 1
+ *              therefore ln(b/(b+1)) = ln(1 - 1/(b+1)) =~ -1/(b+1).
+ *         ln(.1) =~ -2.30
+ *
+ * Proof of (1):
+ *    Solve (factor)**(power) =~ .1 given power (5*loadav):
+ *	solving for factor,
+ *      ln(factor) =~ (-2.30/5*loadav), or
+ *      factor =~ exp(-1/((5/2.30)*loadav)) =~ exp(-1/(2*loadav)) =
+ *          exp(-1/b) =~ (b-1)/b =~ b/(b+1).                    QED
+ *
+ * Proof of (2):
+ *    Solve (factor)**(power) =~ .1 given factor == (b/(b+1)):
+ *	solving for power,
+ *      power*ln(b/(b+1)) =~ -2.30, or
+ *      power =~ 2.3 * (b + 1) = 4.6*loadav + 2.3 =~ 5*loadav.  QED
+ *
+ * Actual power values for the implemented algorithm are as follows:
+ *      loadav: 1       2       3       4
+ *      power:  5.68    10.32   14.94   19.55
+ */
+
+/* calculations for digital decay to forget 90% of usage in 5*loadav sec */
+#define	loadfactor(loadav)	(2 * (loadav))
+#define	decay_cpu(loadfac, cpu)	(((loadfac) * (cpu)) / ((loadfac) + FSCALE))
+
+/* decay 95% of `ts_pctcpu' in 60 seconds; see CCPU_SHIFT before changing */
+static fixpt_t	ccpu = 0.95122942450071400909 * FSCALE;	/* exp(-1/20) */
+SYSCTL_INT(_kern, OID_AUTO, ccpu, CTLFLAG_RD, &ccpu, 0, "");
+
+/*
+ * If `ccpu' is not equal to `exp(-1/20)' and you still want to use the
+ * faster/more-accurate formula, you'll have to estimate CCPU_SHIFT below
+ * and possibly adjust FSHIFT in "param.h" so that (FSHIFT >= CCPU_SHIFT).
+ *
+ * To estimate CCPU_SHIFT for exp(-1/20), the following formula was used:
+ *	1 - exp(-1/20) ~= 0.0487 ~= 0.0488 == 1 (fixed pt, *11* bits).
+ *
+ * If you don't want to bother with the faster/more-accurate formula, you
+ * can set CCPU_SHIFT to (FSHIFT + 1) which will use a slower/less-accurate
+ * (more general) method of calculating the %age of CPU used by a process.
+ */
+#define	CCPU_SHIFT	11
+
+/*
+ * Recompute process priorities, every hz ticks.
+ * MP-safe, called without the Giant mutex.
+ */
+/* ARGSUSED */
+static void
+schedcpu(void)
+{
+	register fixpt_t loadfac = loadfactor(averunnable.ldavg[0]);
+	struct thread *td;
+	struct proc *p;
+	struct td_sched *ts;
+	int awake, realstathz;
+
+	realstathz = stathz ? stathz : hz;
+	sx_slock(&allproc_lock);
+	FOREACH_PROC_IN_SYSTEM(p) {
+		PROC_LOCK(p);
+		FOREACH_THREAD_IN_PROC(p, td) {
+			awake = 0;
+			thread_lock(td);
+			ts = td->td_sched;
+			/*
+			 * Increment sleep time (if sleeping).  We
+			 * ignore overflow, as above.
+			 */
+			/*
+			 * The td_sched slptimes are not touched in wakeup
+			 * because the thread may not HAVE everything in
+			 * memory? XXX I think this is out of date.
+			 */
+			if (TD_ON_RUNQ(td)) {
+				awake = 1;
+				td->td_flags &= ~TDF_DIDRUN;
+			} else if (TD_IS_RUNNING(td)) {
+				awake = 1;
+				/* Do not clear TDF_DIDRUN */
+			} else if (td->td_flags & TDF_DIDRUN) {
+				awake = 1;
+				td->td_flags &= ~TDF_DIDRUN;
+			}
+
+			/*
+			 * ts_pctcpu is only for ps and ttyinfo().
+			 */
+			ts->ts_pctcpu = (ts->ts_pctcpu * ccpu) >> FSHIFT;
+			/*
+			 * If the td_sched has been idle the entire second,
+			 * stop recalculating its priority until
+			 * it wakes up.
+			 */
+			if (ts->ts_cpticks != 0) {
+#if	(FSHIFT >= CCPU_SHIFT)
+				ts->ts_pctcpu += (realstathz == 100)
+				    ? ((fixpt_t) ts->ts_cpticks) <<
+				    (FSHIFT - CCPU_SHIFT) :
+				    100 * (((fixpt_t) ts->ts_cpticks)
+				    << (FSHIFT - CCPU_SHIFT)) / realstathz;
+#else
+				ts->ts_pctcpu += ((FSCALE - ccpu) *
+				    (ts->ts_cpticks *
+				    FSCALE / realstathz)) >> FSHIFT;
+#endif
+				ts->ts_cpticks = 0;
+			}
+			/*
+			 * If there are ANY running threads in this process,
+			 * then don't count it as sleeping.
+			 * XXX: this is broken.
+			 */
+			if (awake) {
+				if (ts->ts_slptime > 1) {
+					/*
+					 * In an ideal world, this should not
+					 * happen, because whoever woke us
+					 * up from the long sleep should have
+					 * unwound the slptime and reset our
+					 * priority before we run at the stale
+					 * priority.  Should KASSERT at some
+					 * point when all the cases are fixed.
+					 */
+					updatepri(td);
+				}
+				ts->ts_slptime = 0;
+			} else
+				ts->ts_slptime++;
+			if (ts->ts_slptime > 1) {
+				thread_unlock(td);
+				continue;
+			}
+			td->td_estcpu = decay_cpu(loadfac, td->td_estcpu);
+		      	resetpriority(td);
+			resetpriority_thread(td);
+			thread_unlock(td);
+		}
+		PROC_UNLOCK(p);
+	}
+	sx_sunlock(&allproc_lock);
+}
+
+/*
+ * Main loop for a kthread that executes schedcpu once a second.
+ */
+static void
+schedcpu_thread(void)
+{
+
+	for (;;) {
+		schedcpu();
+		pause("-", hz);
+	}
+}
+
+/*
+ * Recalculate the priority of a process after it has slept for a while.
+ * For all load averages >= 1 and max td_estcpu of 255, sleeping for at
+ * least six times the loadfactor will decay td_estcpu to zero.
+ */
+static void
+updatepri(struct thread *td)
+{
+	struct td_sched *ts;
+	fixpt_t loadfac;
+	unsigned int newcpu;
+
+	ts = td->td_sched;
+	loadfac = loadfactor(averunnable.ldavg[0]);
+	if (ts->ts_slptime > 5 * loadfac)
+		td->td_estcpu = 0;
+	else {
+		newcpu = td->td_estcpu;
+		ts->ts_slptime--;	/* was incremented in schedcpu() */
+		while (newcpu && --ts->ts_slptime)
+			newcpu = decay_cpu(loadfac, newcpu);
+		td->td_estcpu = newcpu;
+	}
+}
+
+/*
+ * Compute the priority of a process when running in user mode.
+ * Arrange to reschedule if the resulting priority is better
+ * than that of the current process.
+ */
+static void
+resetpriority(struct thread *td)
+{
+	register unsigned int newpriority;
+
+	if (td->td_pri_class == PRI_TIMESHARE) {
+		newpriority = PUSER + td->td_estcpu / INVERSE_ESTCPU_WEIGHT +
+		    NICE_WEIGHT * (td->td_proc->p_nice - PRIO_MIN);
+		newpriority = min(max(newpriority, PRI_MIN_TIMESHARE),
+		    PRI_MAX_TIMESHARE);
+		sched_user_prio(td, newpriority);
+	}
+}
+
+/*
+ * Update the thread's priority when the associated process's user
+ * priority changes.
+ */
+static void
+resetpriority_thread(struct thread *td)
+{
+
+	/* Only change threads with a time sharing user priority. */
+	if (td->td_priority < PRI_MIN_TIMESHARE ||
+	    td->td_priority > PRI_MAX_TIMESHARE)
+		return;
+
+	/* XXX the whole needresched thing is broken, but not silly. */
+	maybe_resched(td);
+
+	sched_prio(td, td->td_user_pri);
+}
+
+/* ARGSUSED */
+static void
+sched_setup(void *dummy)
+{
+	setup_runqs();
+
+	if (sched_quantum == 0)
+		sched_quantum = SCHED_QUANTUM;
+	hogticks = 2 * sched_quantum;
+
+	/* Account for thread0. */
+	sched_load_add();
+}
+
+/* External interfaces start here */
+
+/*
+ * Very early in the boot some setup of scheduler-specific
+ * parts of proc0 and of some scheduler resources needs to be done.
+ * Called from:
+ *  proc0_init()
+ */
+void
+schedinit(void)
+{
+	/*
+	 * Set up the scheduler specific parts of proc0.
+	 */
+	proc0.p_sched = NULL; /* XXX */
+	thread0.td_sched = &td_sched0;
+	thread0.td_lock = &sched_lock;
+	mtx_init(&sched_lock, "sched lock", NULL, MTX_SPIN | MTX_RECURSE);
+}
+
+int
+sched_runnable(void)
+{
+#ifdef SMP
+	return runq_check(&runq) + runq_check(&runq_pcpu[PCPU_GET(cpuid)]);
+#else
+	return runq_check(&runq);
+#endif
+}
+
+int
+sched_rr_interval(void)
+{
+	if (sched_quantum == 0)
+		sched_quantum = SCHED_QUANTUM;
+	return (sched_quantum);
+}
+
+/*
+ * We adjust the priority of the current process.  The priority of
+ * a process gets worse as it accumulates CPU time.  The cpu usage
+ * estimator (td_estcpu) is increased here.  resetpriority() will
+ * compute a different priority each time td_estcpu increases by
+ * INVERSE_ESTCPU_WEIGHT
+ * (until MAXPRI is reached).  The cpu usage estimator ramps up
+ * quite quickly when the process is running (linearly), and decays
+ * away exponentially, at a rate which is proportionally slower when
+ * the system is busy.  The basic principle is that the system will
+ * 90% forget that the process used a lot of CPU time in 5 * loadav
+ * seconds.  This causes the system to favor processes which haven't
+ * run much recently, and to round-robin among other processes.
+ */
+void
+sched_clock(struct thread *td)
+{
+	struct td_sched *ts;
+
+	THREAD_LOCK_ASSERT(td, MA_OWNED);
+	ts = td->td_sched;
+
+	ts->ts_cpticks++;
+	td->td_estcpu = ESTCPULIM(td->td_estcpu + 1);
+	if ((td->td_estcpu % INVERSE_ESTCPU_WEIGHT) == 0) {
+		resetpriority(td);
+		resetpriority_thread(td);
+	}
+
+	/*
+	 * Force a context switch if the current thread has used up a full
+	 * quantum (default quantum is 100ms).
+	 */
+	if (!TD_IS_IDLETHREAD(td) &&
+	    ticks - PCPU_GET(switchticks) >= sched_quantum)
+		td->td_flags |= TDF_NEEDRESCHED;
+}
+
+/*
+ * Charge child's scheduling CPU usage to parent.
+ */
+void
+sched_exit(struct proc *p, struct thread *td)
+{
+
+	KTR_STATE1(KTR_SCHED, "thread", sched_tdname(td), "proc exit",
+	    "prio:%d", td->td_priority);
+
+	PROC_LOCK_ASSERT(p, MA_OWNED);
+	sched_exit_thread(FIRST_THREAD_IN_PROC(p), td);
+}
+
+void
+sched_exit_thread(struct thread *td, struct thread *child)
+{
+
+	KTR_STATE1(KTR_SCHED, "thread", sched_tdname(child), "exit",
+	    "prio:%d", child->td_priority);
+	thread_lock(td);
+	td->td_estcpu = ESTCPULIM(td->td_estcpu + child->td_estcpu);
+	thread_unlock(td);
+	mtx_lock_spin(&sched_lock);
+	if ((child->td_proc->p_flag & P_NOLOAD) == 0)
+		sched_load_rem();
+	mtx_unlock_spin(&sched_lock);
+}
+
+void
+sched_fork(struct thread *td, struct thread *childtd)
+{
+	sched_fork_thread(td, childtd);
+}
+
+void
+sched_fork_thread(struct thread *td, struct thread *childtd)
+{
+	struct td_sched *ts;
+
+	childtd->td_estcpu = td->td_estcpu;
+	childtd->td_lock = &sched_lock;
+	childtd->td_cpuset = cpuset_ref(td->td_cpuset);
+	ts = childtd->td_sched;
+	bzero(ts, sizeof(*ts));
+	ts->ts_flags |= (td->td_sched->ts_flags & TSF_AFFINITY);
+}
+
+void
+sched_nice(struct proc *p, int nice)
+{
+	struct thread *td;
+
+	PROC_LOCK_ASSERT(p, MA_OWNED);
+	p->p_nice = nice;
+	FOREACH_THREAD_IN_PROC(p, td) {
+		thread_lock(td);
+		resetpriority(td);
+		resetpriority_thread(td);
+		thread_unlock(td);
+	}
+}
+
+void
+sched_class(struct thread *td, int class)
+{
+	THREAD_LOCK_ASSERT(td, MA_OWNED);
+	td->td_pri_class = class;
+}
+
+/*
+ * Adjust the priority of a thread.
+ */
+static void
+sched_priority(struct thread *td, u_char prio)
+{
+
+
+	KTR_POINT3(KTR_SCHED, "thread", sched_tdname(td), "priority change",
+	    "prio:%d", td->td_priority, "new prio:%d", prio, KTR_ATTR_LINKED,
+	    sched_tdname(curthread));
+	if (td != curthread && prio > td->td_priority) {
+		KTR_POINT3(KTR_SCHED, "thread", sched_tdname(curthread),
+		    "lend prio", "prio:%d", td->td_priority, "new prio:%d",
+		    prio, KTR_ATTR_LINKED, sched_tdname(td));
+	}
+	THREAD_LOCK_ASSERT(td, MA_OWNED);
+	if (td->td_priority == prio)
+		return;
+	td->td_priority = prio;
+	if (TD_ON_RUNQ(td) && td->td_rqindex != (prio / RQ_PPQ)) {
+		sched_rem(td);
+		sched_add(td, SRQ_BORING);
+	}
+}
+
+/*
+ * Update a thread's priority when it is lent another thread's
+ * priority.
+ */
+void
+sched_lend_prio(struct thread *td, u_char prio)
+{
+
+	td->td_flags |= TDF_BORROWING;
+	sched_priority(td, prio);
+}
+
+/*
+ * Restore a thread's priority when priority propagation is
+ * over.  The prio argument is the minimum priority the thread
+ * needs to have to satisfy other possible priority lending
+ * requests.  If the thread's regulary priority is less
+ * important than prio the thread will keep a priority boost
+ * of prio.
+ */
+void
+sched_unlend_prio(struct thread *td, u_char prio)
+{
+	u_char base_pri;
+
+	if (td->td_base_pri >= PRI_MIN_TIMESHARE &&
+	    td->td_base_pri <= PRI_MAX_TIMESHARE)
+		base_pri = td->td_user_pri;
+	else
+		base_pri = td->td_base_pri;
+	if (prio >= base_pri) {
+		td->td_flags &= ~TDF_BORROWING;
+		sched_prio(td, base_pri);
+	} else
+		sched_lend_prio(td, prio);
+}
+
+void
+sched_prio(struct thread *td, u_char prio)
+{
+	u_char oldprio;
+
+	/* First, update the base priority. */
+	td->td_base_pri = prio;
+
+	/*
+	 * If the thread is borrowing another thread's priority, don't ever
+	 * lower the priority.
+	 */
+	if (td->td_flags & TDF_BORROWING && td->td_priority < prio)
+		return;
+
+	/* Change the real priority. */
+	oldprio = td->td_priority;
+	sched_priority(td, prio);
+
+	/*
+	 * If the thread is on a turnstile, then let the turnstile update
+	 * its state.
+	 */
+	if (TD_ON_LOCK(td) && oldprio != prio)
+		turnstile_adjust(td, oldprio);
+}
+
+void
+sched_user_prio(struct thread *td, u_char prio)
+{
+	u_char oldprio;
+
+	THREAD_LOCK_ASSERT(td, MA_OWNED);
+	td->td_base_user_pri = prio;
+	if (td->td_flags & TDF_UBORROWING && td->td_user_pri <= prio)
+		return;
+	oldprio = td->td_user_pri;
+	td->td_user_pri = prio;
+}
+
+void
+sched_lend_user_prio(struct thread *td, u_char prio)
+{
+	u_char oldprio;
+
+	THREAD_LOCK_ASSERT(td, MA_OWNED);
+	td->td_flags |= TDF_UBORROWING;
+	oldprio = td->td_user_pri;
+	td->td_user_pri = prio;
+}
+
+void
+sched_unlend_user_prio(struct thread *td, u_char prio)
+{
+	u_char base_pri;
+
+	THREAD_LOCK_ASSERT(td, MA_OWNED);
+	base_pri = td->td_base_user_pri;
+	if (prio >= base_pri) {
+		td->td_flags &= ~TDF_UBORROWING;
+		sched_user_prio(td, base_pri);
+	} else {
+		sched_lend_user_prio(td, prio);
+	}
+}
+
+void
+sched_sleep(struct thread *td, int pri)
+{
+
+	THREAD_LOCK_ASSERT(td, MA_OWNED);
+	td->td_slptick = ticks;
+	td->td_sched->ts_slptime = 0;
+	if (pri)
+		sched_prio(td, pri);
+	if (TD_IS_SUSPENDED(td) || pri >= PSOCK)
+		td->td_flags |= TDF_CANSWAP;
+}
+
+void
+sched_switch(struct thread *td, struct thread *newtd, int flags)
+{
+	struct mtx *tmtx;
+	struct td_sched *ts;
+	struct proc *p;
+
+	tmtx = NULL;
+	ts = td->td_sched;
+	p = td->td_proc;
+
+	THREAD_LOCK_ASSERT(td, MA_OWNED);
+
+	/* 
+	 * Switch to the sched lock to fix things up and pick
+	 * a new thread.
+	 * Block the td_lock in order to avoid breaking the critical path.
+	 */
+	if (td->td_lock != &sched_lock) {
+		mtx_lock_spin(&sched_lock);
+		tmtx = thread_lock_block(td);
+	}
+
+	if ((p->p_flag & P_NOLOAD) == 0)
+		sched_load_rem();
+
+	if (newtd) {
+		MPASS(newtd->td_lock == &sched_lock);
+		newtd->td_flags |= (td->td_flags & TDF_NEEDRESCHED);
+	}
+
+	td->td_lastcpu = td->td_oncpu;
+	td->td_flags &= ~TDF_NEEDRESCHED;
+	td->td_owepreempt = 0;
+	td->td_oncpu = NOCPU;
+
+	/*
+	 * At the last moment, if this thread is still marked RUNNING,
+	 * then put it back on the run queue as it has not been suspended
+	 * or stopped or any thing else similar.  We never put the idle
+	 * threads on the run queue, however.
+	 */
+	if (td->td_flags & TDF_IDLETD) {
+		TD_SET_CAN_RUN(td);
+#ifdef SMP
+		idle_cpus_mask &= ~PCPU_GET(cpumask);
+#endif
+	} else {
+		if (TD_IS_RUNNING(td)) {
+			/* Put us back on the run queue. */
+			sched_add(td, (flags & SW_PREEMPT) ?
+			    SRQ_OURSELF|SRQ_YIELDING|SRQ_PREEMPTED :
+			    SRQ_OURSELF|SRQ_YIELDING);
+		}
+	}
+	if (newtd) {
+		/*
+		 * The thread we are about to run needs to be counted
+		 * as if it had been added to the run queue and selected.
+		 * It came from:
+		 * * A preemption
+		 * * An upcall
+		 * * A followon
+		 */
+		KASSERT((newtd->td_inhibitors == 0),
+			("trying to run inhibited thread"));
+		newtd->td_flags |= TDF_DIDRUN;
+        	TD_SET_RUNNING(newtd);
+		if ((newtd->td_proc->p_flag & P_NOLOAD) == 0)
+			sched_load_add();
+	} else {
+		newtd = choosethread();
+		MPASS(newtd->td_lock == &sched_lock);
+	}
+
+	if (td != newtd) {
+#ifdef	HWPMC_HOOKS
+		if (PMC_PROC_IS_USING_PMCS(td->td_proc))

*** DIFF OUTPUT TRUNCATED AT 1000 LINES ***


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