bdc30aed03
to update it, so don't bother with <machine/atomic.h> Flush kernel_lock_release_all() and kernel_lock_acquire_count() (which didn't do spinlock accounting correctly), and replace them with spinlock_release_all() and spinlock_acquire_count().
1002 lines
26 KiB
C
1002 lines
26 KiB
C
/* $NetBSD: kern_synch.c,v 1.90 2000/08/26 19:26:43 sommerfeld Exp $ */
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/*-
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* Copyright (c) 1999, 2000 The NetBSD Foundation, Inc.
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* All rights reserved.
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*
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* This code is derived from software contributed to The NetBSD Foundation
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* by Jason R. Thorpe of the Numerical Aerospace Simulation Facility,
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* NASA Ames Research Center.
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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 NetBSD
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* Foundation, Inc. and its contributors.
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* 4. Neither the name of The NetBSD Foundation nor the names of its
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* contributors may be used to endorse or promote products derived
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* from this software without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS
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* ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED
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* TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR
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* PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS
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* BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
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* CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
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* SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
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* INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
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* CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
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* ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
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* POSSIBILITY OF SUCH DAMAGE.
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*/
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/*-
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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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*/
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#include "opt_ddb.h"
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#include "opt_ktrace.h"
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#include "opt_lockdebug.h"
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#include "opt_multiprocessor.h"
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#include <sys/param.h>
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#include <sys/systm.h>
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#include <sys/callout.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/sched.h>
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#include <uvm/uvm_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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int lbolt; /* once a second sleep address */
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int rrticks; /* number of hardclock ticks per roundrobin() */
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/*
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* The global scheduler state.
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*/
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struct prochd sched_qs[RUNQUE_NQS]; /* run queues */
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__volatile u_int32_t sched_whichqs; /* bitmap of non-empty queues */
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struct slpque sched_slpque[SLPQUE_TABLESIZE]; /* sleep queues */
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struct simplelock sched_lock = SIMPLELOCK_INITIALIZER;
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#if defined(MULTIPROCESSOR)
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struct lock kernel_lock;
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#endif
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void schedcpu(void *);
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void updatepri(struct proc *);
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void endtsleep(void *);
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__inline void awaken(struct proc *);
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struct callout schedcpu_ch = CALLOUT_INITIALIZER;
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/*
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* Force switch among equal priority processes every 100ms.
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* Called from hardclock every hz/10 == rrticks hardclock ticks.
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*/
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/* ARGSUSED */
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void
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roundrobin(struct cpu_info *ci)
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{
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struct schedstate_percpu *spc = &ci->ci_schedstate;
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spc->spc_rrticks = rrticks;
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if (curproc != NULL) {
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if (spc->spc_flags & SPCF_SEENRR) {
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/*
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* The process has already been through a roundrobin
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* without switching and may be hogging the CPU.
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* Indicate that the process should yield.
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*/
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spc->spc_flags |= SPCF_SHOULDYIELD;
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} else
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spc->spc_flags |= SPCF_SEENRR;
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}
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need_resched(curcpu());
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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 hardclock 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(void *arg)
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{
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fixpt_t loadfac = loadfactor(averunnable.ldavg[0]);
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struct proc *p;
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int s, s1;
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unsigned int newcpu;
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int clkhz;
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proclist_lock_read();
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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 = splstatclock(); /* prevent state changes */
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/*
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* p_pctcpu is only for ps.
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*/
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clkhz = stathz != 0 ? stathz : hz;
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#if (FSHIFT >= CCPU_SHIFT)
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p->p_pctcpu += (clkhz == 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)) / clkhz;
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#else
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p->p_pctcpu += ((FSCALE - ccpu) *
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(p->p_cpticks * FSCALE / clkhz)) >> 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);
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p->p_estcpu = newcpu;
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SCHED_LOCK(s1);
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resetpriority(p);
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if (p->p_priority >= PUSER) {
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if (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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remrunqueue(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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SCHED_UNLOCK(s1);
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splx(s);
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}
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proclist_unlock_read();
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uvm_meter();
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wakeup((caddr_t)&lbolt);
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callout_reset(&schedcpu_ch, 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(struct proc *p)
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{
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unsigned int newcpu;
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fixpt_t loadfac;
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SCHED_ASSERT_LOCKED();
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newcpu = p->p_estcpu;
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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 = newcpu;
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}
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resetpriority(p);
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}
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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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/*
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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 interlock is held until the scheduler_slock is held. The
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* interlock will be locked before returning back to the caller
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* unless the PNORELOCK flag is specified, in which case the
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* interlock will always be unlocked upon return.
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*/
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int
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ltsleep(void *ident, int priority, const char *wmesg, int timo,
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__volatile struct simplelock *interlock)
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|
{
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|
struct proc *p = curproc;
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struct slpque *qp;
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int sig, s;
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int catch = priority & PCATCH;
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int relock = (priority & PNORELOCK) == 0;
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|
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/*
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* XXXSMP
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* This is probably bogus. Figure out what the right
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* thing to do here really is.
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* Note that not sleeping if ltsleep is called with curproc == NULL
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* in the shutdown case is disgusting but partly necessary given
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* how shutdown (barely) works.
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*/
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if (cold || (doing_shutdown && (panicstr || (p == NULL)))) {
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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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s = splhigh();
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splx(safepri);
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|
splx(s);
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|
if (interlock != NULL && relock == 0)
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simple_unlock(interlock);
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return (0);
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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, 1, 0);
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|
#endif
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|
|
SCHED_LOCK(s);
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|
|
#ifdef DIAGNOSTIC
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|
if (ident == NULL)
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|
panic("ltsleep: ident == NULL");
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|
if (p->p_stat != SONPROC)
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|
panic("ltsleep: p_stat %d != SONPROC", p->p_stat);
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|
if (p->p_back != NULL)
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|
panic("ltsleep: p_back != NULL");
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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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|
|
qp = SLPQUE(ident);
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|
if (qp->sq_head == 0)
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|
qp->sq_head = p;
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|
else
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|
*qp->sq_tailp = p;
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|
*(qp->sq_tailp = &p->p_forw) = 0;
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|
|
|
if (timo)
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|
callout_reset(&p->p_tsleep_ch, timo, endtsleep, p);
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|
|
|
/*
|
|
* We can now release the interlock; the scheduler_slock
|
|
* is held, so a thread can't get in to do wakeup() before
|
|
* we do the switch.
|
|
*
|
|
* XXX We leave the code block here, after inserting ourselves
|
|
* on the sleep queue, because we might want a more clever
|
|
* data structure for the sleep queues at some point.
|
|
*/
|
|
if (interlock != NULL)
|
|
simple_unlock(interlock);
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|
|
/*
|
|
* We put ourselves on the sleep queue and start our timeout
|
|
* 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.
|
|
* A SIGCONT would cause us to be marked as SSLEEP
|
|
* without resuming us, thus we must be ready for sleep
|
|
* when CURSIG is called. If the wakeup happens while we're
|
|
* stopped, p->p_wchan will be 0 upon return from CURSIG.
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|
*/
|
|
if (catch) {
|
|
p->p_flag |= P_SINTR;
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|
if ((sig = CURSIG(p)) != 0) {
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if (p->p_wchan != NULL)
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unsleep(p);
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p->p_stat = SONPROC;
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|
SCHED_UNLOCK(s);
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|
goto resume;
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|
}
|
|
if (p->p_wchan == NULL) {
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|
catch = 0;
|
|
SCHED_UNLOCK(s);
|
|
goto resume;
|
|
}
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|
} else
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|
sig = 0;
|
|
p->p_stat = SSLEEP;
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|
p->p_stats->p_ru.ru_nvcsw++;
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|
|
SCHED_ASSERT_LOCKED();
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|
mi_switch(p);
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|
|
#ifdef DDB
|
|
/* handy breakpoint location after process "wakes" */
|
|
asm(".globl bpendtsleep ; bpendtsleep:");
|
|
#endif
|
|
|
|
SCHED_ASSERT_UNLOCKED();
|
|
splx(s);
|
|
|
|
resume:
|
|
KDASSERT(p->p_cpu != NULL);
|
|
KDASSERT(p->p_cpu == curcpu());
|
|
p->p_cpu->ci_schedstate.spc_curpriority = p->p_usrpri;
|
|
|
|
p->p_flag &= ~P_SINTR;
|
|
if (p->p_flag & P_TIMEOUT) {
|
|
p->p_flag &= ~P_TIMEOUT;
|
|
if (sig == 0) {
|
|
#ifdef KTRACE
|
|
if (KTRPOINT(p, KTR_CSW))
|
|
ktrcsw(p, 0, 0);
|
|
#endif
|
|
if (relock && interlock != NULL)
|
|
simple_lock(interlock);
|
|
return (EWOULDBLOCK);
|
|
}
|
|
} else if (timo)
|
|
callout_stop(&p->p_tsleep_ch);
|
|
if (catch && (sig != 0 || (sig = CURSIG(p)) != 0)) {
|
|
#ifdef KTRACE
|
|
if (KTRPOINT(p, KTR_CSW))
|
|
ktrcsw(p, 0, 0);
|
|
#endif
|
|
if (relock && interlock != NULL)
|
|
simple_lock(interlock);
|
|
if ((p->p_sigacts->ps_sigact[sig].sa_flags & SA_RESTART) == 0)
|
|
return (EINTR);
|
|
return (ERESTART);
|
|
}
|
|
#ifdef KTRACE
|
|
if (KTRPOINT(p, KTR_CSW))
|
|
ktrcsw(p, 0, 0);
|
|
#endif
|
|
if (relock && interlock != NULL)
|
|
simple_lock(interlock);
|
|
return (0);
|
|
}
|
|
|
|
/*
|
|
* Implement timeout for tsleep.
|
|
* 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.
|
|
*/
|
|
void
|
|
endtsleep(void *arg)
|
|
{
|
|
struct proc *p;
|
|
int s;
|
|
|
|
p = (struct proc *)arg;
|
|
|
|
SCHED_LOCK(s);
|
|
if (p->p_wchan) {
|
|
if (p->p_stat == SSLEEP)
|
|
setrunnable(p);
|
|
else
|
|
unsleep(p);
|
|
p->p_flag |= P_TIMEOUT;
|
|
}
|
|
SCHED_UNLOCK(s);
|
|
}
|
|
|
|
/*
|
|
* Remove a process from its wait queue
|
|
*/
|
|
void
|
|
unsleep(struct proc *p)
|
|
{
|
|
struct slpque *qp;
|
|
struct proc **hp;
|
|
|
|
SCHED_ASSERT_LOCKED();
|
|
|
|
if (p->p_wchan) {
|
|
hp = &(qp = SLPQUE(p->p_wchan))->sq_head;
|
|
while (*hp != p)
|
|
hp = &(*hp)->p_forw;
|
|
*hp = p->p_forw;
|
|
if (qp->sq_tailp == &p->p_forw)
|
|
qp->sq_tailp = hp;
|
|
p->p_wchan = 0;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Optimized-for-wakeup() version of setrunnable().
|
|
*/
|
|
__inline void
|
|
awaken(struct proc *p)
|
|
{
|
|
|
|
SCHED_ASSERT_LOCKED();
|
|
|
|
if (p->p_slptime > 1)
|
|
updatepri(p);
|
|
p->p_slptime = 0;
|
|
p->p_stat = SRUN;
|
|
|
|
/*
|
|
* Since curpriority is a user priority, p->p_priority
|
|
* is always better than curpriority.
|
|
*/
|
|
if (p->p_flag & P_INMEM) {
|
|
setrunqueue(p);
|
|
KASSERT(p->p_cpu != NULL);
|
|
need_resched(p->p_cpu);
|
|
} else
|
|
sched_wakeup(&proc0);
|
|
}
|
|
|
|
#if defined(MULTIPROCESSOR) || defined(LOCKDEBUG)
|
|
void
|
|
sched_unlock_idle(void)
|
|
{
|
|
|
|
simple_unlock(&sched_lock);
|
|
}
|
|
|
|
void
|
|
sched_lock_idle(void)
|
|
{
|
|
|
|
simple_lock(&sched_lock);
|
|
}
|
|
#endif /* MULTIPROCESSOR || LOCKDEBUG */
|
|
|
|
/*
|
|
* Make all processes sleeping on the specified identifier runnable.
|
|
*/
|
|
|
|
void
|
|
wakeup(void *ident)
|
|
{
|
|
int s;
|
|
|
|
SCHED_ASSERT_UNLOCKED();
|
|
|
|
SCHED_LOCK(s);
|
|
sched_wakeup(ident);
|
|
SCHED_UNLOCK(s);
|
|
}
|
|
|
|
void
|
|
sched_wakeup(void *ident)
|
|
{
|
|
struct slpque *qp;
|
|
struct proc *p, **q;
|
|
|
|
SCHED_ASSERT_LOCKED();
|
|
|
|
qp = SLPQUE(ident);
|
|
restart:
|
|
for (q = &qp->sq_head; (p = *q) != NULL; ) {
|
|
#ifdef DIAGNOSTIC
|
|
if (p->p_back || (p->p_stat != SSLEEP && p->p_stat != SSTOP))
|
|
panic("wakeup");
|
|
#endif
|
|
if (p->p_wchan == ident) {
|
|
p->p_wchan = 0;
|
|
*q = p->p_forw;
|
|
if (qp->sq_tailp == &p->p_forw)
|
|
qp->sq_tailp = q;
|
|
if (p->p_stat == SSLEEP) {
|
|
awaken(p);
|
|
goto restart;
|
|
}
|
|
} else
|
|
q = &p->p_forw;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Make the highest priority process first in line on the specified
|
|
* identifier runnable.
|
|
*/
|
|
void
|
|
wakeup_one(void *ident)
|
|
{
|
|
struct slpque *qp;
|
|
struct proc *p, **q;
|
|
struct proc *best_sleepp, **best_sleepq;
|
|
struct proc *best_stopp, **best_stopq;
|
|
int s;
|
|
|
|
best_sleepp = best_stopp = NULL;
|
|
best_sleepq = best_stopq = NULL;
|
|
|
|
SCHED_LOCK(s);
|
|
|
|
qp = SLPQUE(ident);
|
|
|
|
for (q = &qp->sq_head; (p = *q) != NULL; q = &p->p_forw) {
|
|
#ifdef DIAGNOSTIC
|
|
if (p->p_back || (p->p_stat != SSLEEP && p->p_stat != SSTOP))
|
|
panic("wakeup_one");
|
|
#endif
|
|
if (p->p_wchan == ident) {
|
|
if (p->p_stat == SSLEEP) {
|
|
if (best_sleepp == NULL ||
|
|
p->p_priority < best_sleepp->p_priority) {
|
|
best_sleepp = p;
|
|
best_sleepq = q;
|
|
}
|
|
} else {
|
|
if (best_stopp == NULL ||
|
|
p->p_priority < best_stopp->p_priority) {
|
|
best_stopp = p;
|
|
best_stopq = q;
|
|
}
|
|
}
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Consider any SSLEEP process higher than the highest priority SSTOP
|
|
* process.
|
|
*/
|
|
if (best_sleepp != NULL) {
|
|
p = best_sleepp;
|
|
q = best_sleepq;
|
|
} else {
|
|
p = best_stopp;
|
|
q = best_stopq;
|
|
}
|
|
|
|
if (p != NULL) {
|
|
p->p_wchan = NULL;
|
|
*q = p->p_forw;
|
|
if (qp->sq_tailp == &p->p_forw)
|
|
qp->sq_tailp = q;
|
|
if (p->p_stat == SSLEEP)
|
|
awaken(p);
|
|
}
|
|
SCHED_UNLOCK(s);
|
|
}
|
|
|
|
/*
|
|
* General yield call. Puts the current process back on its run queue and
|
|
* performs a voluntary context switch.
|
|
*/
|
|
void
|
|
yield(void)
|
|
{
|
|
struct proc *p = curproc;
|
|
int s;
|
|
|
|
SCHED_LOCK(s);
|
|
p->p_priority = p->p_usrpri;
|
|
p->p_stat = SRUN;
|
|
setrunqueue(p);
|
|
p->p_stats->p_ru.ru_nvcsw++;
|
|
mi_switch(p);
|
|
SCHED_ASSERT_UNLOCKED();
|
|
splx(s);
|
|
}
|
|
|
|
/*
|
|
* General preemption call. Puts the current process back on its run queue
|
|
* and performs an involuntary context switch. If a process is supplied,
|
|
* we switch to that process. Otherwise, we use the normal process selection
|
|
* criteria.
|
|
*/
|
|
void
|
|
preempt(struct proc *newp)
|
|
{
|
|
struct proc *p = curproc;
|
|
int s;
|
|
|
|
/*
|
|
* XXX Switching to a specific process is not supported yet.
|
|
*/
|
|
if (newp != NULL)
|
|
panic("preempt: cpu_preempt not yet implemented");
|
|
|
|
SCHED_LOCK(s);
|
|
p->p_priority = p->p_usrpri;
|
|
p->p_stat = SRUN;
|
|
setrunqueue(p);
|
|
p->p_stats->p_ru.ru_nivcsw++;
|
|
mi_switch(p);
|
|
SCHED_ASSERT_UNLOCKED();
|
|
splx(s);
|
|
}
|
|
|
|
/*
|
|
* The machine independent parts of context switch.
|
|
* Must be called at splsched() (no higher!) and with
|
|
* the sched_lock held.
|
|
*/
|
|
void
|
|
mi_switch(struct proc *p)
|
|
{
|
|
struct schedstate_percpu *spc;
|
|
struct rlimit *rlim;
|
|
long s, u;
|
|
struct timeval tv;
|
|
#if defined(MULTIPROCESSOR)
|
|
int hold_count;
|
|
#endif
|
|
|
|
SCHED_ASSERT_LOCKED();
|
|
|
|
#if defined(MULTIPROCESSOR)
|
|
/*
|
|
* Release the kernel_lock, as we are about to yield the CPU.
|
|
* The scheduler lock is still held until cpu_switch()
|
|
* selects a new process and removes it from the run queue.
|
|
*/
|
|
if (p->p_flag & P_BIGLOCK)
|
|
hold_count = spinlock_release_all(&kernel_lock);
|
|
#endif
|
|
|
|
KDASSERT(p->p_cpu != NULL);
|
|
KDASSERT(p->p_cpu == curcpu());
|
|
|
|
spc = &p->p_cpu->ci_schedstate;
|
|
|
|
#if defined(LOCKDEBUG) || defined(DIAGNOSTIC)
|
|
spinlock_switchcheck();
|
|
#endif
|
|
#ifdef LOCKDEBUG
|
|
simple_lock_switchcheck();
|
|
#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 - spc->spc_runtime.tv_usec);
|
|
s = p->p_rtime.tv_sec + (tv.tv_sec - spc->spc_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. In any case, if it has run for more
|
|
* than 10 minutes, reduce priority to give others a chance.
|
|
*/
|
|
rlim = &p->p_rlimit[RLIMIT_CPU];
|
|
if (s >= rlim->rlim_cur) {
|
|
if (s >= rlim->rlim_max)
|
|
psignal(p, SIGKILL);
|
|
else {
|
|
psignal(p, SIGXCPU);
|
|
if (rlim->rlim_cur < rlim->rlim_max)
|
|
rlim->rlim_cur += 5;
|
|
}
|
|
}
|
|
if (autonicetime && s > autonicetime && p->p_ucred->cr_uid &&
|
|
p->p_nice == NZERO) {
|
|
p->p_nice = autoniceval + NZERO;
|
|
resetpriority(p);
|
|
}
|
|
|
|
/*
|
|
* Process is about to yield the CPU; clear the appropriate
|
|
* scheduling flags.
|
|
*/
|
|
spc->spc_flags &= ~SPCF_SWITCHCLEAR;
|
|
|
|
/*
|
|
* Pick a new current process and switch to it. When we
|
|
* run again, we'll return back here.
|
|
*/
|
|
uvmexp.swtch++;
|
|
cpu_switch(p);
|
|
|
|
/*
|
|
* Make sure that MD code released the scheduler lock before
|
|
* resuming us.
|
|
*/
|
|
SCHED_ASSERT_UNLOCKED();
|
|
|
|
/*
|
|
* We're running again; record our new start time. We might
|
|
* be running on a new CPU now, so don't use the cache'd
|
|
* schedstate_percpu pointer.
|
|
*/
|
|
KDASSERT(p->p_cpu != NULL);
|
|
KDASSERT(p->p_cpu == curcpu());
|
|
microtime(&p->p_cpu->ci_schedstate.spc_runtime);
|
|
|
|
#if defined(MULTIPROCESSOR)
|
|
/*
|
|
* Reacquire the kernel_lock now. We do this after we've
|
|
* released the scheduler lock to avoid deadlock, and before
|
|
* we reacquire the interlock.
|
|
*/
|
|
if (p->p_flag & P_BIGLOCK)
|
|
spinlock_acquire_count(&kernel_lock, hold_count);
|
|
#endif
|
|
}
|
|
|
|
/*
|
|
* Initialize the (doubly-linked) run queues
|
|
* to be empty.
|
|
*/
|
|
void
|
|
rqinit()
|
|
{
|
|
int i;
|
|
|
|
for (i = 0; i < RUNQUE_NQS; i++)
|
|
sched_qs[i].ph_link = sched_qs[i].ph_rlink =
|
|
(struct proc *)&sched_qs[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(struct proc *p)
|
|
{
|
|
|
|
SCHED_ASSERT_LOCKED();
|
|
|
|
switch (p->p_stat) {
|
|
case 0:
|
|
case SRUN:
|
|
case SONPROC:
|
|
case SZOMB:
|
|
case SDEAD:
|
|
default:
|
|
panic("setrunnable");
|
|
case SSTOP:
|
|
/*
|
|
* If we're being traced (possibly because someone attached us
|
|
* while we were stopped), check for a signal from the debugger.
|
|
*/
|
|
if ((p->p_flag & P_TRACED) != 0 && p->p_xstat != 0) {
|
|
sigaddset(&p->p_siglist, p->p_xstat);
|
|
p->p_sigcheck = 1;
|
|
}
|
|
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);
|
|
|
|
if (p->p_slptime > 1)
|
|
updatepri(p);
|
|
p->p_slptime = 0;
|
|
if ((p->p_flag & P_INMEM) == 0)
|
|
sched_wakeup((caddr_t)&proc0);
|
|
else if (p->p_priority < curcpu()->ci_schedstate.spc_curpriority) {
|
|
/*
|
|
* XXXSMP
|
|
* This is not exactly right. Since p->p_cpu persists
|
|
* across a context switch, this gives us some sort
|
|
* of processor affinity. But we need to figure out
|
|
* at what point it's better to reschedule on a different
|
|
* CPU than the last one.
|
|
*/
|
|
need_resched((p->p_cpu != NULL) ? p->p_cpu : curcpu());
|
|
}
|
|
}
|
|
|
|
/*
|
|
* 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(struct proc *p)
|
|
{
|
|
unsigned int newpriority;
|
|
|
|
SCHED_ASSERT_LOCKED();
|
|
|
|
newpriority = PUSER + p->p_estcpu + NICE_WEIGHT * (p->p_nice - NZERO);
|
|
newpriority = min(newpriority, MAXPRI);
|
|
p->p_usrpri = newpriority;
|
|
if (newpriority < curcpu()->ci_schedstate.spc_curpriority) {
|
|
/*
|
|
* XXXSMP
|
|
* Same applies as in setrunnable() above.
|
|
*/
|
|
need_resched((p->p_cpu != NULL) ? p->p_cpu : curcpu());
|
|
}
|
|
}
|
|
|
|
/*
|
|
* 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. The formula for computing priorities (in kern_synch.c)
|
|
* will compute a different value each time p_estcpu increases. This can
|
|
* cause a switch, but unless the priority crosses a PPQ boundary the actual
|
|
* queue will not change. 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(struct proc *p)
|
|
{
|
|
int s;
|
|
|
|
p->p_estcpu = ESTCPULIM(p->p_estcpu + 1);
|
|
|
|
SCHED_LOCK(s);
|
|
resetpriority(p);
|
|
SCHED_UNLOCK(s);
|
|
|
|
if (p->p_priority >= PUSER)
|
|
p->p_priority = p->p_usrpri;
|
|
}
|