918c3b1361
Synchronize syscalls.master with all MPSAFE changes to date. Synchronize new syscall generation follows because yield() will panic if it is out of sync with syscalls.master.
868 lines
24 KiB
C
868 lines
24 KiB
C
/*-
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* Copyright (c) 1982, 1986, 1990, 1991, 1993
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* The Regents of the University of California. All rights reserved.
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* (c) UNIX System Laboratories, Inc.
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* All or some portions of this file are derived from material licensed
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* to the University of California by American Telephone and Telegraph
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* Co. or Unix System Laboratories, Inc. and are reproduced herein with
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* the permission of UNIX System Laboratories, Inc.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by the University of
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* California, Berkeley and its contributors.
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* 4. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* @(#)kern_synch.c 8.9 (Berkeley) 5/19/95
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* $FreeBSD$
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*/
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#include "opt_ddb.h"
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#include "opt_ktrace.h"
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#include <sys/param.h>
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#include <sys/systm.h>
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#include <sys/condvar.h>
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#include <sys/kernel.h>
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#include <sys/ktr.h>
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#include <sys/lock.h>
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#include <sys/mutex.h>
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#include <sys/proc.h>
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#include <sys/resourcevar.h>
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#include <sys/signalvar.h>
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#include <sys/smp.h>
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#include <sys/sx.h>
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#include <sys/sysctl.h>
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#include <sys/sysproto.h>
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#include <sys/vmmeter.h>
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#include <vm/vm.h>
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#include <vm/vm_extern.h>
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#ifdef DDB
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#include <ddb/ddb.h>
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#endif
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#ifdef KTRACE
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#include <sys/uio.h>
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#include <sys/ktrace.h>
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#endif
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#include <machine/cpu.h>
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static void sched_setup __P((void *dummy));
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SYSINIT(sched_setup, SI_SUB_KICK_SCHEDULER, SI_ORDER_FIRST, sched_setup, NULL)
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int hogticks;
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int lbolt;
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int sched_quantum; /* Roundrobin scheduling quantum in ticks. */
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static struct callout schedcpu_callout;
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static struct callout roundrobin_callout;
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static void endtsleep __P((void *));
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static void roundrobin __P((void *arg));
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static void schedcpu __P((void *arg));
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static int
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sysctl_kern_quantum(SYSCTL_HANDLER_ARGS)
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{
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int error, new_val;
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new_val = sched_quantum * tick;
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error = sysctl_handle_int(oidp, &new_val, 0, req);
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if (error != 0 || req->newptr == NULL)
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return (error);
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if (new_val < tick)
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return (EINVAL);
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sched_quantum = new_val / tick;
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hogticks = 2 * sched_quantum;
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return (0);
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}
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SYSCTL_PROC(_kern, OID_AUTO, quantum, CTLTYPE_INT|CTLFLAG_RW,
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0, sizeof sched_quantum, sysctl_kern_quantum, "I", "");
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/*
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* Arrange to reschedule if necessary, taking the priorities and
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* schedulers into account.
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*/
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void
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maybe_resched(p)
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struct proc *p;
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{
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mtx_assert(&sched_lock, MA_OWNED);
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if (p->p_pri.pri_level < curproc->p_pri.pri_level)
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curproc->p_sflag |= PS_NEEDRESCHED;
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}
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int
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roundrobin_interval(void)
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{
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return (sched_quantum);
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}
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/*
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* Force switch among equal priority processes every 100ms.
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* We don't actually need to force a context switch of the current process.
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* The act of firing the event triggers a context switch to softclock() and
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* then switching back out again which is equivalent to a preemption, thus
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* no further work is needed on the local CPU.
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*/
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/* ARGSUSED */
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static void
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roundrobin(arg)
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void *arg;
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{
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#ifdef SMP
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mtx_lock_spin(&sched_lock);
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forward_roundrobin();
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mtx_unlock_spin(&sched_lock);
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#endif
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callout_reset(&roundrobin_callout, sched_quantum, roundrobin, NULL);
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}
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/*
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* Constants for digital decay and forget:
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* 90% of (p_estcpu) usage in 5 * loadav time
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* 95% of (p_pctcpu) usage in 60 seconds (load insensitive)
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* Note that, as ps(1) mentions, this can let percentages
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* total over 100% (I've seen 137.9% for 3 processes).
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*
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* Note that schedclock() updates p_estcpu and p_cpticks asynchronously.
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*
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* We wish to decay away 90% of p_estcpu in (5 * loadavg) seconds.
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* That is, the system wants to compute a value of decay such
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* that the following for loop:
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* for (i = 0; i < (5 * loadavg); i++)
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* p_estcpu *= decay;
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* will compute
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* p_estcpu *= 0.1;
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* for all values of loadavg:
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*
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* Mathematically this loop can be expressed by saying:
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* decay ** (5 * loadavg) ~= .1
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*
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* The system computes decay as:
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* decay = (2 * loadavg) / (2 * loadavg + 1)
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*
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* We wish to prove that the system's computation of decay
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* will always fulfill the equation:
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* decay ** (5 * loadavg) ~= .1
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*
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* If we compute b as:
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* b = 2 * loadavg
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* then
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* decay = b / (b + 1)
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*
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* We now need to prove two things:
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* 1) Given factor ** (5 * loadavg) ~= .1, prove factor == b/(b+1)
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* 2) Given b/(b+1) ** power ~= .1, prove power == (5 * loadavg)
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*
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* Facts:
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* For x close to zero, exp(x) =~ 1 + x, since
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* exp(x) = 0! + x**1/1! + x**2/2! + ... .
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* therefore exp(-1/b) =~ 1 - (1/b) = (b-1)/b.
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* For x close to zero, ln(1+x) =~ x, since
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* ln(1+x) = x - x**2/2 + x**3/3 - ... -1 < x < 1
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* therefore ln(b/(b+1)) = ln(1 - 1/(b+1)) =~ -1/(b+1).
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* ln(.1) =~ -2.30
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*
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* Proof of (1):
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* Solve (factor)**(power) =~ .1 given power (5*loadav):
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* solving for factor,
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* ln(factor) =~ (-2.30/5*loadav), or
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* factor =~ exp(-1/((5/2.30)*loadav)) =~ exp(-1/(2*loadav)) =
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* exp(-1/b) =~ (b-1)/b =~ b/(b+1). QED
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*
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* Proof of (2):
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* Solve (factor)**(power) =~ .1 given factor == (b/(b+1)):
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* solving for power,
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* power*ln(b/(b+1)) =~ -2.30, or
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* power =~ 2.3 * (b + 1) = 4.6*loadav + 2.3 =~ 5*loadav. QED
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*
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* Actual power values for the implemented algorithm are as follows:
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* loadav: 1 2 3 4
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* power: 5.68 10.32 14.94 19.55
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*/
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/* calculations for digital decay to forget 90% of usage in 5*loadav sec */
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#define loadfactor(loadav) (2 * (loadav))
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#define decay_cpu(loadfac, cpu) (((loadfac) * (cpu)) / ((loadfac) + FSCALE))
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/* decay 95% of `p_pctcpu' in 60 seconds; see CCPU_SHIFT before changing */
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static fixpt_t ccpu = 0.95122942450071400909 * FSCALE; /* exp(-1/20) */
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SYSCTL_INT(_kern, OID_AUTO, ccpu, CTLFLAG_RD, &ccpu, 0, "");
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/* kernel uses `FSCALE', userland (SHOULD) use kern.fscale */
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static int fscale __unused = FSCALE;
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SYSCTL_INT(_kern, OID_AUTO, fscale, CTLFLAG_RD, 0, FSCALE, "");
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/*
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* If `ccpu' is not equal to `exp(-1/20)' and you still want to use the
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* faster/more-accurate formula, you'll have to estimate CCPU_SHIFT below
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* and possibly adjust FSHIFT in "param.h" so that (FSHIFT >= CCPU_SHIFT).
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*
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* To estimate CCPU_SHIFT for exp(-1/20), the following formula was used:
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* 1 - exp(-1/20) ~= 0.0487 ~= 0.0488 == 1 (fixed pt, *11* bits).
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*
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* If you don't want to bother with the faster/more-accurate formula, you
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* can set CCPU_SHIFT to (FSHIFT + 1) which will use a slower/less-accurate
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* (more general) method of calculating the %age of CPU used by a process.
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*/
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#define CCPU_SHIFT 11
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/*
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* Recompute process priorities, every hz ticks.
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* MP-safe, called without the Giant mutex.
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*/
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/* ARGSUSED */
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static void
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schedcpu(arg)
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void *arg;
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{
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register fixpt_t loadfac = loadfactor(averunnable.ldavg[0]);
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register struct proc *p;
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register int realstathz;
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realstathz = stathz ? stathz : hz;
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sx_slock(&allproc_lock);
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LIST_FOREACH(p, &allproc, p_list) {
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/*
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* Increment time in/out of memory and sleep time
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* (if sleeping). We ignore overflow; with 16-bit int's
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* (remember them?) overflow takes 45 days.
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*/
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mtx_lock_spin(&sched_lock);
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p->p_swtime++;
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if (p->p_stat == SSLEEP || p->p_stat == SSTOP)
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p->p_slptime++;
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p->p_pctcpu = (p->p_pctcpu * ccpu) >> FSHIFT;
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/*
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* If the process has slept the entire second,
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* stop recalculating its priority until it wakes up.
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*/
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if (p->p_slptime > 1) {
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mtx_unlock_spin(&sched_lock);
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continue;
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}
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/*
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* p_pctcpu is only for ps.
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*/
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#if (FSHIFT >= CCPU_SHIFT)
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p->p_pctcpu += (realstathz == 100)?
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((fixpt_t) p->p_cpticks) << (FSHIFT - CCPU_SHIFT):
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100 * (((fixpt_t) p->p_cpticks)
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<< (FSHIFT - CCPU_SHIFT)) / realstathz;
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#else
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p->p_pctcpu += ((FSCALE - ccpu) *
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(p->p_cpticks * FSCALE / realstathz)) >> FSHIFT;
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#endif
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p->p_cpticks = 0;
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p->p_estcpu = decay_cpu(loadfac, p->p_estcpu);
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resetpriority(p);
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if (p->p_pri.pri_level >= PUSER) {
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if (p->p_oncpu == NOCPU && /* idle */
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p->p_stat == SRUN &&
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(p->p_sflag & PS_INMEM) &&
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(p->p_pri.pri_level / RQ_PPQ) !=
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(p->p_pri.pri_user / RQ_PPQ)) {
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remrunqueue(p);
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p->p_pri.pri_level = p->p_pri.pri_user;
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setrunqueue(p);
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} else
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p->p_pri.pri_level = p->p_pri.pri_user;
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}
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mtx_unlock_spin(&sched_lock);
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}
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sx_sunlock(&allproc_lock);
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vmmeter();
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wakeup((caddr_t)&lbolt);
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callout_reset(&schedcpu_callout, hz, schedcpu, NULL);
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}
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/*
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* Recalculate the priority of a process after it has slept for a while.
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* For all load averages >= 1 and max p_estcpu of 255, sleeping for at
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* least six times the loadfactor will decay p_estcpu to zero.
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*/
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void
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updatepri(p)
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register struct proc *p;
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{
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register unsigned int newcpu = p->p_estcpu;
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register fixpt_t loadfac = loadfactor(averunnable.ldavg[0]);
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if (p->p_slptime > 5 * loadfac)
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p->p_estcpu = 0;
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else {
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p->p_slptime--; /* the first time was done in schedcpu */
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while (newcpu && --p->p_slptime)
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newcpu = decay_cpu(loadfac, newcpu);
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p->p_estcpu = newcpu;
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}
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resetpriority(p);
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}
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/*
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* We're only looking at 7 bits of the address; everything is
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* aligned to 4, lots of things are aligned to greater powers
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* of 2. Shift right by 8, i.e. drop the bottom 256 worth.
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*/
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#define TABLESIZE 128
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static TAILQ_HEAD(slpquehead, proc) slpque[TABLESIZE];
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#define LOOKUP(x) (((intptr_t)(x) >> 8) & (TABLESIZE - 1))
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void
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sleepinit(void)
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{
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int i;
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sched_quantum = hz/10;
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hogticks = 2 * sched_quantum;
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for (i = 0; i < TABLESIZE; i++)
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TAILQ_INIT(&slpque[i]);
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}
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/*
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* General sleep call. Suspends the current process until a wakeup is
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* performed on the specified identifier. The process will then be made
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* runnable with the specified priority. Sleeps at most timo/hz seconds
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* (0 means no timeout). If pri includes PCATCH flag, signals are checked
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* before and after sleeping, else signals are not checked. Returns 0 if
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* awakened, EWOULDBLOCK if the timeout expires. If PCATCH is set and a
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* signal needs to be delivered, ERESTART is returned if the current system
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* call should be restarted if possible, and EINTR is returned if the system
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* call should be interrupted by the signal (return EINTR).
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*
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* The mutex argument is exited before the caller is suspended, and
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* entered before msleep returns. If priority includes the PDROP
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* flag the mutex is not entered before returning.
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*/
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int
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msleep(ident, mtx, priority, wmesg, timo)
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void *ident;
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struct mtx *mtx;
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int priority, timo;
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const char *wmesg;
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{
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struct proc *p = curproc;
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int sig, catch = priority & PCATCH;
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int rval = 0;
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WITNESS_SAVE_DECL(mtx);
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#ifdef KTRACE
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if (p && KTRPOINT(p, KTR_CSW))
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ktrcsw(p->p_tracep, 1, 0);
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#endif
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WITNESS_SLEEP(0, &mtx->mtx_object);
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KASSERT(timo != 0 || mtx_owned(&Giant) || mtx != NULL,
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("sleeping without a mutex"));
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mtx_lock_spin(&sched_lock);
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if (cold || panicstr) {
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/*
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* After a panic, or during autoconfiguration,
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* just give interrupts a chance, then just return;
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* don't run any other procs or panic below,
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* in case this is the idle process and already asleep.
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*/
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if (mtx != NULL && priority & PDROP)
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mtx_unlock_flags(mtx, MTX_NOSWITCH);
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mtx_unlock_spin(&sched_lock);
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return (0);
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}
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DROP_GIANT_NOSWITCH();
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if (mtx != NULL) {
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mtx_assert(mtx, MA_OWNED | MA_NOTRECURSED);
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WITNESS_SAVE(&mtx->mtx_object, mtx);
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mtx_unlock_flags(mtx, MTX_NOSWITCH);
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if (priority & PDROP)
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mtx = NULL;
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}
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KASSERT(p != NULL, ("msleep1"));
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KASSERT(ident != NULL && p->p_stat == SRUN, ("msleep"));
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p->p_wchan = ident;
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p->p_wmesg = wmesg;
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p->p_slptime = 0;
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p->p_pri.pri_level = priority & PRIMASK;
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CTR5(KTR_PROC, "msleep: proc %p (pid %d, %s) on %s (%p)", p, p->p_pid,
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p->p_comm, wmesg, ident);
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TAILQ_INSERT_TAIL(&slpque[LOOKUP(ident)], p, p_slpq);
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if (timo)
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callout_reset(&p->p_slpcallout, timo, endtsleep, p);
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/*
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* We put ourselves on the sleep queue and start our timeout
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* before calling CURSIG, as we could stop there, and a wakeup
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* or a SIGCONT (or both) could occur while we were stopped.
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* A SIGCONT would cause us to be marked as SSLEEP
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* without resuming us, thus we must be ready for sleep
|
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* when CURSIG is called. If the wakeup happens while we're
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* stopped, p->p_wchan will be 0 upon return from CURSIG.
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*/
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if (catch) {
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CTR3(KTR_PROC, "msleep caught: proc %p (pid %d, %s)", p,
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p->p_pid, p->p_comm);
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p->p_sflag |= PS_SINTR;
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mtx_unlock_spin(&sched_lock);
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PROC_LOCK(p);
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sig = CURSIG(p);
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mtx_lock_spin(&sched_lock);
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PROC_UNLOCK_NOSWITCH(p);
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if (sig != 0) {
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if (p->p_wchan != NULL)
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unsleep(p);
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} else if (p->p_wchan == NULL)
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catch = 0;
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} else
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sig = 0;
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if (p->p_wchan != NULL) {
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p->p_stat = SSLEEP;
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p->p_stats->p_ru.ru_nvcsw++;
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mi_switch();
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}
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CTR3(KTR_PROC, "msleep resume: proc %p (pid %d, %s)", p, p->p_pid,
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p->p_comm);
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KASSERT(p->p_stat == SRUN, ("running but not SRUN"));
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p->p_sflag &= ~PS_SINTR;
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if (p->p_sflag & PS_TIMEOUT) {
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p->p_sflag &= ~PS_TIMEOUT;
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if (sig == 0)
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rval = EWOULDBLOCK;
|
|
} else if (p->p_sflag & PS_TIMOFAIL)
|
|
p->p_sflag &= ~PS_TIMOFAIL;
|
|
else if (timo && callout_stop(&p->p_slpcallout) == 0) {
|
|
/*
|
|
* This isn't supposed to be pretty. If we are here, then
|
|
* the endtsleep() callout is currently executing on another
|
|
* CPU and is either spinning on the sched_lock or will be
|
|
* soon. If we don't synchronize here, there is a chance
|
|
* that this process may msleep() again before the callout
|
|
* has a chance to run and the callout may end up waking up
|
|
* the wrong msleep(). Yuck.
|
|
*/
|
|
p->p_sflag |= PS_TIMEOUT;
|
|
p->p_stats->p_ru.ru_nivcsw++;
|
|
mi_switch();
|
|
}
|
|
mtx_unlock_spin(&sched_lock);
|
|
|
|
if (rval == 0 && catch) {
|
|
PROC_LOCK(p);
|
|
/* XXX: shouldn't we always be calling CURSIG() */
|
|
if (sig != 0 || (sig = CURSIG(p))) {
|
|
if (SIGISMEMBER(p->p_sigacts->ps_sigintr, sig))
|
|
rval = EINTR;
|
|
else
|
|
rval = ERESTART;
|
|
}
|
|
PROC_UNLOCK(p);
|
|
}
|
|
PICKUP_GIANT();
|
|
#ifdef KTRACE
|
|
mtx_lock(&Giant);
|
|
if (KTRPOINT(p, KTR_CSW))
|
|
ktrcsw(p->p_tracep, 0, 0);
|
|
mtx_unlock(&Giant);
|
|
#endif
|
|
if (mtx != NULL) {
|
|
mtx_lock(mtx);
|
|
WITNESS_RESTORE(&mtx->mtx_object, mtx);
|
|
}
|
|
return (rval);
|
|
}
|
|
|
|
/*
|
|
* Implement timeout for msleep()
|
|
*
|
|
* If process hasn't been awakened (wchan non-zero),
|
|
* set timeout flag and undo the sleep. If proc
|
|
* is stopped, just unsleep so it will remain stopped.
|
|
* MP-safe, called without the Giant mutex.
|
|
*/
|
|
static void
|
|
endtsleep(arg)
|
|
void *arg;
|
|
{
|
|
register struct proc *p;
|
|
|
|
p = (struct proc *)arg;
|
|
CTR3(KTR_PROC, "endtsleep: proc %p (pid %d, %s)", p, p->p_pid,
|
|
p->p_comm);
|
|
mtx_lock_spin(&sched_lock);
|
|
/*
|
|
* This is the other half of the synchronization with msleep()
|
|
* described above. If the PS_TIMEOUT flag is set, we lost the
|
|
* race and just need to put the process back on the runqueue.
|
|
*/
|
|
if ((p->p_sflag & PS_TIMEOUT) != 0) {
|
|
p->p_sflag &= ~PS_TIMEOUT;
|
|
setrunqueue(p);
|
|
} else if (p->p_wchan != NULL) {
|
|
if (p->p_stat == SSLEEP)
|
|
setrunnable(p);
|
|
else
|
|
unsleep(p);
|
|
p->p_sflag |= PS_TIMEOUT;
|
|
} else
|
|
p->p_sflag |= PS_TIMOFAIL;
|
|
mtx_unlock_spin(&sched_lock);
|
|
}
|
|
|
|
/*
|
|
* Remove a process from its wait queue
|
|
*/
|
|
void
|
|
unsleep(p)
|
|
register struct proc *p;
|
|
{
|
|
|
|
mtx_lock_spin(&sched_lock);
|
|
if (p->p_wchan != NULL) {
|
|
TAILQ_REMOVE(&slpque[LOOKUP(p->p_wchan)], p, p_slpq);
|
|
p->p_wchan = NULL;
|
|
}
|
|
mtx_unlock_spin(&sched_lock);
|
|
}
|
|
|
|
/*
|
|
* Make all processes sleeping on the specified identifier runnable.
|
|
*/
|
|
void
|
|
wakeup(ident)
|
|
register void *ident;
|
|
{
|
|
register struct slpquehead *qp;
|
|
register struct proc *p;
|
|
|
|
mtx_lock_spin(&sched_lock);
|
|
qp = &slpque[LOOKUP(ident)];
|
|
restart:
|
|
TAILQ_FOREACH(p, qp, p_slpq) {
|
|
if (p->p_wchan == ident) {
|
|
TAILQ_REMOVE(qp, p, p_slpq);
|
|
p->p_wchan = NULL;
|
|
if (p->p_stat == SSLEEP) {
|
|
/* OPTIMIZED EXPANSION OF setrunnable(p); */
|
|
CTR3(KTR_PROC, "wakeup: proc %p (pid %d, %s)",
|
|
p, p->p_pid, p->p_comm);
|
|
if (p->p_slptime > 1)
|
|
updatepri(p);
|
|
p->p_slptime = 0;
|
|
p->p_stat = SRUN;
|
|
if (p->p_sflag & PS_INMEM) {
|
|
setrunqueue(p);
|
|
maybe_resched(p);
|
|
} else {
|
|
p->p_sflag |= PS_SWAPINREQ;
|
|
wakeup((caddr_t)&proc0);
|
|
}
|
|
/* END INLINE EXPANSION */
|
|
goto restart;
|
|
}
|
|
}
|
|
}
|
|
mtx_unlock_spin(&sched_lock);
|
|
}
|
|
|
|
/*
|
|
* Make a process sleeping on the specified identifier runnable.
|
|
* May wake more than one process if a target process is currently
|
|
* swapped out.
|
|
*/
|
|
void
|
|
wakeup_one(ident)
|
|
register void *ident;
|
|
{
|
|
register struct slpquehead *qp;
|
|
register struct proc *p;
|
|
|
|
mtx_lock_spin(&sched_lock);
|
|
qp = &slpque[LOOKUP(ident)];
|
|
|
|
TAILQ_FOREACH(p, qp, p_slpq) {
|
|
if (p->p_wchan == ident) {
|
|
TAILQ_REMOVE(qp, p, p_slpq);
|
|
p->p_wchan = NULL;
|
|
if (p->p_stat == SSLEEP) {
|
|
/* OPTIMIZED EXPANSION OF setrunnable(p); */
|
|
CTR3(KTR_PROC, "wakeup1: proc %p (pid %d, %s)",
|
|
p, p->p_pid, p->p_comm);
|
|
if (p->p_slptime > 1)
|
|
updatepri(p);
|
|
p->p_slptime = 0;
|
|
p->p_stat = SRUN;
|
|
if (p->p_sflag & PS_INMEM) {
|
|
setrunqueue(p);
|
|
maybe_resched(p);
|
|
break;
|
|
} else {
|
|
p->p_sflag |= PS_SWAPINREQ;
|
|
wakeup((caddr_t)&proc0);
|
|
}
|
|
/* END INLINE EXPANSION */
|
|
}
|
|
}
|
|
}
|
|
mtx_unlock_spin(&sched_lock);
|
|
}
|
|
|
|
/*
|
|
* The machine independent parts of mi_switch().
|
|
*/
|
|
void
|
|
mi_switch()
|
|
{
|
|
struct timeval new_switchtime;
|
|
register struct proc *p = curproc; /* XXX */
|
|
#if 0
|
|
register struct rlimit *rlim;
|
|
#endif
|
|
critical_t sched_crit;
|
|
u_int sched_nest;
|
|
|
|
mtx_assert(&sched_lock, MA_OWNED | MA_NOTRECURSED);
|
|
|
|
/*
|
|
* Compute the amount of time during which the current
|
|
* process was running, and add that to its total so far.
|
|
*/
|
|
microuptime(&new_switchtime);
|
|
if (timevalcmp(&new_switchtime, PCPU_PTR(switchtime), <)) {
|
|
#if 0
|
|
/* XXX: This doesn't play well with sched_lock right now. */
|
|
printf("microuptime() went backwards (%ld.%06ld -> %ld.%06ld)\n",
|
|
PCPU_GET(switchtime.tv_sec), PCPU_GET(switchtime.tv_usec),
|
|
new_switchtime.tv_sec, new_switchtime.tv_usec);
|
|
#endif
|
|
new_switchtime = PCPU_GET(switchtime);
|
|
} else {
|
|
p->p_runtime += (new_switchtime.tv_usec - PCPU_GET(switchtime.tv_usec)) +
|
|
(new_switchtime.tv_sec - PCPU_GET(switchtime.tv_sec)) *
|
|
(int64_t)1000000;
|
|
}
|
|
|
|
#ifdef DDB
|
|
/*
|
|
* Don't perform context switches from the debugger.
|
|
*/
|
|
if (db_active) {
|
|
mtx_unlock_spin(&sched_lock);
|
|
db_error("Context switches not allowed in the debugger.");
|
|
}
|
|
#endif
|
|
|
|
#if 0
|
|
/*
|
|
* Check if the process exceeds its cpu resource allocation.
|
|
* If over max, kill it.
|
|
*
|
|
* XXX drop sched_lock, pickup Giant
|
|
*/
|
|
if (p->p_stat != SZOMB && p->p_limit->p_cpulimit != RLIM_INFINITY &&
|
|
p->p_runtime > p->p_limit->p_cpulimit) {
|
|
rlim = &p->p_rlimit[RLIMIT_CPU];
|
|
if (p->p_runtime / (rlim_t)1000000 >= rlim->rlim_max) {
|
|
mtx_unlock_spin(&sched_lock);
|
|
PROC_LOCK(p);
|
|
killproc(p, "exceeded maximum CPU limit");
|
|
mtx_lock_spin(&sched_lock);
|
|
PROC_UNLOCK_NOSWITCH(p);
|
|
} else {
|
|
mtx_unlock_spin(&sched_lock);
|
|
PROC_LOCK(p);
|
|
psignal(p, SIGXCPU);
|
|
mtx_lock_spin(&sched_lock);
|
|
PROC_UNLOCK_NOSWITCH(p);
|
|
if (rlim->rlim_cur < rlim->rlim_max) {
|
|
/* XXX: we should make a private copy */
|
|
rlim->rlim_cur += 5;
|
|
}
|
|
}
|
|
}
|
|
#endif
|
|
|
|
/*
|
|
* Pick a new current process and record its start time.
|
|
*/
|
|
cnt.v_swtch++;
|
|
PCPU_SET(switchtime, new_switchtime);
|
|
CTR3(KTR_PROC, "mi_switch: old proc %p (pid %d, %s)", p, p->p_pid,
|
|
p->p_comm);
|
|
sched_crit = sched_lock.mtx_savecrit;
|
|
sched_nest = sched_lock.mtx_recurse;
|
|
p->p_lastcpu = p->p_oncpu;
|
|
p->p_oncpu = NOCPU;
|
|
p->p_sflag &= ~PS_NEEDRESCHED;
|
|
cpu_switch();
|
|
p->p_oncpu = PCPU_GET(cpuid);
|
|
sched_lock.mtx_savecrit = sched_crit;
|
|
sched_lock.mtx_recurse = sched_nest;
|
|
sched_lock.mtx_lock = (uintptr_t)p;
|
|
CTR3(KTR_PROC, "mi_switch: new proc %p (pid %d, %s)", p, p->p_pid,
|
|
p->p_comm);
|
|
if (PCPU_GET(switchtime.tv_sec) == 0)
|
|
microuptime(PCPU_PTR(switchtime));
|
|
PCPU_SET(switchticks, ticks);
|
|
}
|
|
|
|
/*
|
|
* Change process state to be runnable,
|
|
* placing it on the run queue if it is in memory,
|
|
* and awakening the swapper if it isn't in memory.
|
|
*/
|
|
void
|
|
setrunnable(p)
|
|
register struct proc *p;
|
|
{
|
|
|
|
mtx_lock_spin(&sched_lock);
|
|
switch (p->p_stat) {
|
|
case 0:
|
|
case SRUN:
|
|
case SZOMB:
|
|
case SWAIT:
|
|
default:
|
|
panic("setrunnable");
|
|
case SSTOP:
|
|
case SSLEEP: /* e.g. when sending signals */
|
|
if (p->p_sflag & PS_CVWAITQ)
|
|
cv_waitq_remove(p);
|
|
else
|
|
unsleep(p);
|
|
break;
|
|
|
|
case SIDL:
|
|
break;
|
|
}
|
|
p->p_stat = SRUN;
|
|
if (p->p_slptime > 1)
|
|
updatepri(p);
|
|
p->p_slptime = 0;
|
|
if ((p->p_sflag & PS_INMEM) == 0) {
|
|
p->p_sflag |= PS_SWAPINREQ;
|
|
wakeup((caddr_t)&proc0);
|
|
} else {
|
|
setrunqueue(p);
|
|
maybe_resched(p);
|
|
}
|
|
mtx_unlock_spin(&sched_lock);
|
|
}
|
|
|
|
/*
|
|
* 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.
|
|
*/
|
|
void
|
|
resetpriority(p)
|
|
register struct proc *p;
|
|
{
|
|
register unsigned int newpriority;
|
|
|
|
mtx_lock_spin(&sched_lock);
|
|
if (p->p_pri.pri_class == PRI_TIMESHARE) {
|
|
newpriority = PUSER + p->p_estcpu / INVERSE_ESTCPU_WEIGHT +
|
|
NICE_WEIGHT * (p->p_nice - PRIO_MIN);
|
|
newpriority = min(max(newpriority, PRI_MIN_TIMESHARE),
|
|
PRI_MAX_TIMESHARE);
|
|
p->p_pri.pri_user = newpriority;
|
|
}
|
|
maybe_resched(p);
|
|
mtx_unlock_spin(&sched_lock);
|
|
}
|
|
|
|
/* ARGSUSED */
|
|
static void
|
|
sched_setup(dummy)
|
|
void *dummy;
|
|
{
|
|
|
|
callout_init(&schedcpu_callout, 1);
|
|
callout_init(&roundrobin_callout, 0);
|
|
|
|
/* Kick off timeout driven events by calling first time. */
|
|
roundrobin(NULL);
|
|
schedcpu(NULL);
|
|
}
|
|
|
|
/*
|
|
* We adjust the priority of the current process. The priority of
|
|
* a process gets worse as it accumulates CPU time. The cpu usage
|
|
* estimator (p_estcpu) is increased here. resetpriority() will
|
|
* compute a different priority each time p_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
|
|
schedclock(p)
|
|
struct proc *p;
|
|
{
|
|
|
|
p->p_cpticks++;
|
|
p->p_estcpu = ESTCPULIM(p->p_estcpu + 1);
|
|
if ((p->p_estcpu % INVERSE_ESTCPU_WEIGHT) == 0) {
|
|
resetpriority(p);
|
|
if (p->p_pri.pri_level >= PUSER)
|
|
p->p_pri.pri_level = p->p_pri.pri_user;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* General purpose yield system call
|
|
*/
|
|
int
|
|
yield(struct proc *p, struct yield_args *uap)
|
|
{
|
|
p->p_retval[0] = 0;
|
|
|
|
mtx_lock_spin(&sched_lock);
|
|
mtx_assert(&Giant, MA_NOTOWNED);
|
|
#if 0
|
|
DROP_GIANT_NOSWITCH();
|
|
#endif
|
|
p->p_pri.pri_level = PRI_MAX_TIMESHARE;
|
|
setrunqueue(p);
|
|
p->p_stats->p_ru.ru_nvcsw++;
|
|
mi_switch();
|
|
mtx_unlock_spin(&sched_lock);
|
|
#if 0
|
|
PICKUP_GIANT();
|
|
#endif
|
|
|
|
return (0);
|
|
}
|
|
|