679 lines
18 KiB
C
679 lines
18 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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* $Id: kern_synch.c,v 1.29 1997/02/22 09:39:12 peter Exp $
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*/
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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/proc.h>
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#include <sys/kernel.h>
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#include <sys/buf.h>
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#include <sys/signalvar.h>
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#include <sys/resourcevar.h>
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#include <sys/signalvar.h>
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#include <sys/vmmeter.h>
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#include <vm/vm.h>
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#include <vm/vm_param.h>
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#include <vm/vm_extern.h>
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#ifdef KTRACE
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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 rqinit __P((void *));
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SYSINIT(runqueue, SI_SUB_RUN_QUEUE, SI_ORDER_FIRST, rqinit, NULL)
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u_char curpriority; /* usrpri of curproc */
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int lbolt; /* once a second sleep address */
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extern void endtsleep __P((void *));
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extern void updatepri __P((struct proc *p));
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/*
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* Force switch among equal priority processes every 100ms.
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*/
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/* ARGSUSED */
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void
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roundrobin(arg)
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void *arg;
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{
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need_resched();
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timeout(roundrobin, NULL, hz / 10);
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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 statclock updates p_estcpu and p_cpticks independently.
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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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fixpt_t ccpu = 0.95122942450071400909 * FSCALE; /* exp(-1/20) */
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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 dont 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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*/
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/* ARGSUSED */
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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 s;
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register unsigned int newcpu;
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wakeup((caddr_t)&lbolt);
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for (p = allproc.lh_first; p != 0; p = p->p_list.le_next) {
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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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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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continue;
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s = splhigh(); /* prevent state changes and protect run queue */
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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 += (hz == 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)) / hz;
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#else
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p->p_pctcpu += ((FSCALE - ccpu) *
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(p->p_cpticks * FSCALE / hz)) >> FSHIFT;
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#endif
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p->p_cpticks = 0;
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newcpu = (u_int) decay_cpu(loadfac, p->p_estcpu) + p->p_nice;
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p->p_estcpu = min(newcpu, UCHAR_MAX);
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resetpriority(p);
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if (p->p_priority >= PUSER) {
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#define PPQ (128 / NQS) /* priorities per queue */
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if ((p != curproc) &&
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p->p_stat == SRUN &&
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(p->p_flag & P_INMEM) &&
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(p->p_priority / PPQ) != (p->p_usrpri / PPQ)) {
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remrq(p);
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p->p_priority = p->p_usrpri;
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setrunqueue(p);
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} else
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p->p_priority = p->p_usrpri;
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}
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splx(s);
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}
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vmmeter();
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timeout(schedcpu, (void *)0, hz);
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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 = (int) decay_cpu(loadfac, newcpu);
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p->p_estcpu = min(newcpu, UCHAR_MAX);
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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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TAILQ_HEAD(slpquehead, proc) slpque[TABLESIZE];
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#define LOOKUP(x) (((long)(x) >> 8) & (TABLESIZE - 1))
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/*
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* During autoconfiguration or after a panic, a sleep will simply
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* lower the priority briefly to allow interrupts, then return.
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* The priority to be used (safepri) is machine-dependent, thus this
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* value is initialized and maintained in the machine-dependent layers.
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* This priority will typically be 0, or the lowest priority
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* that is safe for use on the interrupt stack; it can be made
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* higher to block network software interrupts after panics.
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*/
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int safepri;
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void
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sleepinit()
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{
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int i;
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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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int
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tsleep(ident, priority, wmesg, timo)
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void *ident;
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int priority, timo;
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char *wmesg;
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{
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struct proc *p = curproc;
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int s, sig, catch = priority & PCATCH;
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#ifdef KTRACE
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if (KTRPOINT(p, KTR_CSW))
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ktrcsw(p->p_tracep, 1, 0);
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#endif
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s = splhigh();
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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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splx(safepri);
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splx(s);
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return (0);
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}
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#ifdef DIAGNOSTIC
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if (ident == NULL || p->p_stat != SRUN)
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panic("tsleep");
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#endif
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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_priority = priority & PRIMASK;
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TAILQ_INSERT_TAIL(&slpque[LOOKUP(ident)], p, p_procq);
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if (timo)
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timeout(endtsleep, (void *)p, timo);
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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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p->p_flag |= P_SINTR;
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if ((sig = CURSIG(p))) {
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if (p->p_wchan)
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unsleep(p);
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p->p_stat = SRUN;
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goto resume;
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}
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if (p->p_wchan == 0) {
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catch = 0;
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goto resume;
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}
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} else
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sig = 0;
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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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resume:
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curpriority = p->p_usrpri;
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splx(s);
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p->p_flag &= ~P_SINTR;
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if (p->p_flag & P_TIMEOUT) {
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p->p_flag &= ~P_TIMEOUT;
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if (sig == 0) {
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#ifdef KTRACE
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if (KTRPOINT(p, KTR_CSW))
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ktrcsw(p->p_tracep, 0, 0);
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#endif
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return (EWOULDBLOCK);
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}
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} else if (timo)
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untimeout(endtsleep, (void *)p);
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if (catch && (sig != 0 || (sig = CURSIG(p)))) {
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#ifdef KTRACE
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if (KTRPOINT(p, KTR_CSW))
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ktrcsw(p->p_tracep, 0, 0);
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#endif
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if (p->p_sigacts->ps_sigintr & sigmask(sig))
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return (EINTR);
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return (ERESTART);
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}
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#ifdef KTRACE
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if (KTRPOINT(p, KTR_CSW))
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ktrcsw(p->p_tracep, 0, 0);
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#endif
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return (0);
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}
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/*
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* Implement timeout for tsleep.
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* If process hasn't been awakened (wchan non-zero),
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* set timeout flag and undo the sleep. If proc
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* is stopped, just unsleep so it will remain stopped.
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*/
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void
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endtsleep(arg)
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void *arg;
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{
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register struct proc *p;
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int s;
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p = (struct proc *)arg;
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s = splhigh();
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if (p->p_wchan) {
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if (p->p_stat == SSLEEP)
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setrunnable(p);
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else
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unsleep(p);
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p->p_flag |= P_TIMEOUT;
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}
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splx(s);
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}
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/*
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* Remove a process from its wait queue
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*/
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void
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unsleep(p)
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register struct proc *p;
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{
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int s;
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s = splhigh();
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if (p->p_wchan) {
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TAILQ_REMOVE(&slpque[LOOKUP(p->p_wchan)], p, p_procq);
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p->p_wchan = 0;
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}
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splx(s);
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}
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/*
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* Make all processes sleeping on the specified identifier runnable.
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*/
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void
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wakeup(ident)
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register void *ident;
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{
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register struct slpquehead *qp;
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register struct proc *p;
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int s;
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s = splhigh();
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qp = &slpque[LOOKUP(ident)];
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restart:
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for (p = qp->tqh_first; p != NULL; p = p->p_procq.tqe_next) {
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#ifdef DIAGNOSTIC
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if (p->p_stat != SSLEEP && p->p_stat != SSTOP)
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panic("wakeup");
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#endif
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if (p->p_wchan == ident) {
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TAILQ_REMOVE(qp, p, p_procq);
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p->p_wchan = 0;
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if (p->p_stat == SSLEEP) {
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/* OPTIMIZED EXPANSION OF setrunnable(p); */
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if (p->p_slptime > 1)
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updatepri(p);
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p->p_slptime = 0;
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p->p_stat = SRUN;
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if (p->p_flag & P_INMEM) {
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setrunqueue(p);
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need_resched();
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} else {
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p->p_flag |= P_SWAPINREQ;
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wakeup((caddr_t)&proc0);
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}
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/* END INLINE EXPANSION */
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goto restart;
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}
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}
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}
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splx(s);
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}
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/*
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* Make a process sleeping on the specified identifier runnable.
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* May wake more than one process if a target prcoess is currently
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* swapped out.
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*/
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void
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wakeup_one(ident)
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register void *ident;
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{
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register struct slpquehead *qp;
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register struct proc *p;
|
|
int s;
|
|
|
|
s = splhigh();
|
|
qp = &slpque[LOOKUP(ident)];
|
|
|
|
for (p = qp->tqh_first; p != NULL; p = p->p_procq.tqe_next) {
|
|
#ifdef DIAGNOSTIC
|
|
if (p->p_stat != SSLEEP && p->p_stat != SSTOP)
|
|
panic("wakeup_one");
|
|
#endif
|
|
if (p->p_wchan == ident) {
|
|
TAILQ_REMOVE(qp, p, p_procq);
|
|
p->p_wchan = 0;
|
|
if (p->p_stat == SSLEEP) {
|
|
/* OPTIMIZED EXPANSION OF setrunnable(p); */
|
|
if (p->p_slptime > 1)
|
|
updatepri(p);
|
|
p->p_slptime = 0;
|
|
p->p_stat = SRUN;
|
|
if (p->p_flag & P_INMEM) {
|
|
setrunqueue(p);
|
|
need_resched();
|
|
break;
|
|
} else {
|
|
p->p_flag |= P_SWAPINREQ;
|
|
wakeup((caddr_t)&proc0);
|
|
}
|
|
/* END INLINE EXPANSION */
|
|
}
|
|
}
|
|
}
|
|
splx(s);
|
|
}
|
|
|
|
/*
|
|
* The machine independent parts of mi_switch().
|
|
* Must be called at splstatclock() or higher.
|
|
*/
|
|
void
|
|
mi_switch()
|
|
{
|
|
register struct proc *p = curproc; /* XXX */
|
|
register struct rlimit *rlim;
|
|
register long s, u;
|
|
int x;
|
|
struct timeval tv;
|
|
|
|
/*
|
|
* XXX this spl is almost unnecessary. It is partly to allow for
|
|
* sloppy callers that don't do it (issignal() via CURSIG() is the
|
|
* main offender). It is partly to work around a bug in the i386
|
|
* cpu_switch() (the ipl is not preserved). We ran for years
|
|
* without it. I think there was only a interrupt latency problem.
|
|
* The main caller, tsleep(), does an splx() a couple of instructions
|
|
* after calling here. The buggy caller, issignal(), usually calls
|
|
* here at spl0() and sometimes returns at splhigh(). The process
|
|
* then runs for a little too long at splhigh(). The ipl gets fixed
|
|
* when the process returns to user mode (or earlier).
|
|
*
|
|
* It would probably be better to always call here at spl0(). Callers
|
|
* are prepared to give up control to another process, so they must
|
|
* be prepared to be interrupted. The clock stuff here may not
|
|
* actually need splstatclock().
|
|
*/
|
|
x = splstatclock();
|
|
|
|
#ifdef SIMPLELOCK_DEBUG
|
|
if (p->p_simple_locks)
|
|
printf("sleep: holding simple lock");
|
|
#endif
|
|
/*
|
|
* Compute the amount of time during which the current
|
|
* process was running, and add that to its total so far.
|
|
*/
|
|
microtime(&tv);
|
|
u = p->p_rtime.tv_usec + (tv.tv_usec - runtime.tv_usec);
|
|
s = p->p_rtime.tv_sec + (tv.tv_sec - runtime.tv_sec);
|
|
if (u < 0) {
|
|
u += 1000000;
|
|
s--;
|
|
} else if (u >= 1000000) {
|
|
u -= 1000000;
|
|
s++;
|
|
}
|
|
p->p_rtime.tv_usec = u;
|
|
p->p_rtime.tv_sec = s;
|
|
|
|
/*
|
|
* Check if the process exceeds its cpu resource allocation.
|
|
* If over max, kill it.
|
|
*/
|
|
if (p->p_stat != SZOMB) {
|
|
rlim = &p->p_rlimit[RLIMIT_CPU];
|
|
if (s >= rlim->rlim_cur) {
|
|
if (s >= rlim->rlim_max)
|
|
killproc(p, "exceeded maximum CPU limit");
|
|
else {
|
|
psignal(p, SIGXCPU);
|
|
if (rlim->rlim_cur < rlim->rlim_max)
|
|
rlim->rlim_cur += 5;
|
|
}
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Pick a new current process and record its start time.
|
|
*/
|
|
cnt.v_swtch++;
|
|
cpu_switch(p);
|
|
microtime(&runtime);
|
|
splx(x);
|
|
}
|
|
|
|
/*
|
|
* Initialize the (doubly-linked) run queues
|
|
* to be empty.
|
|
*/
|
|
/* ARGSUSED*/
|
|
static void
|
|
rqinit(dummy)
|
|
void *dummy;
|
|
{
|
|
register int i;
|
|
|
|
for (i = 0; i < NQS; i++) {
|
|
qs[i].ph_link = qs[i].ph_rlink = (struct proc *)&qs[i];
|
|
rtqs[i].ph_link = rtqs[i].ph_rlink = (struct proc *)&rtqs[i];
|
|
idqs[i].ph_link = idqs[i].ph_rlink = (struct proc *)&idqs[i];
|
|
}
|
|
}
|
|
|
|
/*
|
|
* 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;
|
|
{
|
|
register int s;
|
|
|
|
s = splhigh();
|
|
switch (p->p_stat) {
|
|
case 0:
|
|
case SRUN:
|
|
case SZOMB:
|
|
default:
|
|
panic("setrunnable");
|
|
case SSTOP:
|
|
case SSLEEP:
|
|
unsleep(p); /* e.g. when sending signals */
|
|
break;
|
|
|
|
case SIDL:
|
|
break;
|
|
}
|
|
p->p_stat = SRUN;
|
|
if (p->p_flag & P_INMEM)
|
|
setrunqueue(p);
|
|
splx(s);
|
|
if (p->p_slptime > 1)
|
|
updatepri(p);
|
|
p->p_slptime = 0;
|
|
if ((p->p_flag & P_INMEM) == 0) {
|
|
p->p_flag |= P_SWAPINREQ;
|
|
wakeup((caddr_t)&proc0);
|
|
}
|
|
else if (p->p_priority < curpriority)
|
|
need_resched();
|
|
}
|
|
|
|
/*
|
|
* 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;
|
|
|
|
if (p->p_rtprio.type == RTP_PRIO_NORMAL) {
|
|
newpriority = PUSER + p->p_estcpu / 4 + 2 * p->p_nice;
|
|
newpriority = min(newpriority, MAXPRI);
|
|
p->p_usrpri = newpriority;
|
|
if (newpriority < curpriority)
|
|
need_resched();
|
|
} else {
|
|
need_resched();
|
|
}
|
|
}
|