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freebsd-skq/sys/kern/kern_synch.c

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/*-
* Copyright (c) 1982, 1986, 1990, 1991, 1993
* The Regents of the University of California. All rights reserved.
* (c) UNIX System Laboratories, Inc.
* All or some portions of this file are derived from material licensed
* to the University of California by American Telephone and Telegraph
* Co. or Unix System Laboratories, Inc. and are reproduced herein with
* the permission of UNIX System Laboratories, Inc.
*
* Redistribution and use in source and binary forms, with or without
* modification, are permitted provided that the following conditions
* are met:
* 1. Redistributions of source code must retain the above copyright
* notice, this list of conditions and the following disclaimer.
* 2. Redistributions in binary form must reproduce the above copyright
* notice, this list of conditions and the following disclaimer in the
* documentation and/or other materials provided with the distribution.
* 3. All advertising materials mentioning features or use of this software
* must display the following acknowledgement:
* This product includes software developed by the University of
* California, Berkeley and its contributors.
* 4. Neither the name of the University nor the names of its contributors
* may be used to endorse or promote products derived from this software
* without specific prior written permission.
*
* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
* SUCH DAMAGE.
*
* @(#)kern_synch.c 8.9 (Berkeley) 5/19/95
* $FreeBSD$
*/
#include "opt_ktrace.h"
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/proc.h>
#include <sys/kernel.h>
#include <sys/signalvar.h>
#include <sys/resourcevar.h>
#include <sys/vmmeter.h>
#include <sys/sysctl.h>
#include <vm/vm.h>
#include <vm/vm_extern.h>
#ifdef KTRACE
#include <sys/uio.h>
#include <sys/ktrace.h>
#endif
#include <machine/cpu.h>
#include <machine/ipl.h>
#include <machine/smp.h>
static void sched_setup __P((void *dummy));
SYSINIT(sched_setup, SI_SUB_KICK_SCHEDULER, SI_ORDER_FIRST, sched_setup, NULL)
u_char curpriority;
int hogticks;
int lbolt;
int sched_quantum; /* Roundrobin scheduling quantum in ticks. */
static int curpriority_cmp __P((struct proc *p));
static void endtsleep __P((void *));
static void maybe_resched __P((struct proc *chk));
static void roundrobin __P((void *arg));
static void schedcpu __P((void *arg));
static void updatepri __P((struct proc *p));
static int
sysctl_kern_quantum SYSCTL_HANDLER_ARGS
{
int error, new_val;
new_val = sched_quantum * tick;
error = sysctl_handle_int(oidp, &new_val, 0, req);
if (error != 0 || req->newptr == NULL)
return (error);
if (new_val < tick)
return (EINVAL);
sched_quantum = new_val / tick;
hogticks = 2 * sched_quantum;
return (0);
}
SYSCTL_PROC(_kern, OID_AUTO, quantum, CTLTYPE_INT|CTLFLAG_RW,
0, sizeof sched_quantum, sysctl_kern_quantum, "I", "");
/*-
* Compare priorities. Return:
* <0: priority of p < current priority
* 0: priority of p == current priority
* >0: priority of p > current priority
* The priorities are the normal priorities or the normal realtime priorities
* if p is on the same scheduler as curproc. Otherwise the process on the
* more realtimeish scheduler has lowest priority. As usual, a higher
* priority really means a lower priority.
*/
static int
curpriority_cmp(p)
struct proc *p;
{
int c_class, p_class;
c_class = RTP_PRIO_BASE(curproc->p_rtprio.type);
p_class = RTP_PRIO_BASE(p->p_rtprio.type);
if (p_class != c_class)
return (p_class - c_class);
if (p_class == RTP_PRIO_NORMAL)
return (((int)p->p_priority - (int)curpriority) / PPQ);
return ((int)p->p_rtprio.prio - (int)curproc->p_rtprio.prio);
}
/*
* Arrange to reschedule if necessary, taking the priorities and
* schedulers into account.
*/
static void
maybe_resched(chk)
struct proc *chk;
{
struct proc *p = curproc; /* XXX */
/*
* XXX idle scheduler still broken because proccess stays on idle
* scheduler during waits (such as when getting FS locks). If a
* standard process becomes runaway cpu-bound, the system can lockup
* due to idle-scheduler processes in wakeup never getting any cpu.
*/
if (p == NULL) {
#if 0
need_resched();
#endif
} else if (chk == p) {
/* We may need to yield if our priority has been raised. */
if (curpriority_cmp(chk) > 0)
need_resched();
} else if (curpriority_cmp(chk) < 0)
need_resched();
}
int
roundrobin_interval(void)
{
return (sched_quantum);
}
/*
* Force switch among equal priority processes every 100ms.
*/
/* ARGSUSED */
static void
roundrobin(arg)
void *arg;
{
#ifndef SMP
struct proc *p = curproc; /* XXX */
#endif
#ifdef SMP
need_resched();
forward_roundrobin();
#else
if (p == 0 || RTP_PRIO_NEED_RR(p->p_rtprio.type))
need_resched();
#endif
timeout(roundrobin, NULL, sched_quantum);
}
/*
* Constants for digital decay and forget:
* 90% of (p_estcpu) usage in 5 * loadav time
* 95% of (p_pctcpu) usage in 60 seconds (load insensitive)
* Note that, as ps(1) mentions, this can let percentages
* total over 100% (I've seen 137.9% for 3 processes).
*
* Note that schedclock() updates p_estcpu and p_cpticks asynchronously.
*
* We wish to decay away 90% of p_estcpu in (5 * loadavg) seconds.
* That is, the system wants to compute a value of decay such
* that the following for loop:
* for (i = 0; i < (5 * loadavg); i++)
* p_estcpu *= decay;
* will compute
* p_estcpu *= 0.1;
* for all values of loadavg:
*
* Mathematically this loop can be expressed by saying:
* decay ** (5 * loadavg) ~= .1
*
* The system computes decay as:
* decay = (2 * loadavg) / (2 * loadavg + 1)
*
* We wish to prove that the system's computation of decay
* will always fulfill the equation:
* decay ** (5 * loadavg) ~= .1
*
* If we compute b as:
* b = 2 * loadavg
* then
* decay = b / (b + 1)
*
* We now need to prove two things:
* 1) Given factor ** (5 * loadavg) ~= .1, prove factor == b/(b+1)
* 2) Given b/(b+1) ** power ~= .1, prove power == (5 * loadavg)
*
* Facts:
* For x close to zero, exp(x) =~ 1 + x, since
* exp(x) = 0! + x**1/1! + x**2/2! + ... .
* therefore exp(-1/b) =~ 1 - (1/b) = (b-1)/b.
* For x close to zero, ln(1+x) =~ x, since
* ln(1+x) = x - x**2/2 + x**3/3 - ... -1 < x < 1
* therefore ln(b/(b+1)) = ln(1 - 1/(b+1)) =~ -1/(b+1).
* ln(.1) =~ -2.30
*
* Proof of (1):
* Solve (factor)**(power) =~ .1 given power (5*loadav):
* solving for factor,
* ln(factor) =~ (-2.30/5*loadav), or
* factor =~ exp(-1/((5/2.30)*loadav)) =~ exp(-1/(2*loadav)) =
* exp(-1/b) =~ (b-1)/b =~ b/(b+1). QED
*
* Proof of (2):
* Solve (factor)**(power) =~ .1 given factor == (b/(b+1)):
* solving for power,
* power*ln(b/(b+1)) =~ -2.30, or
* power =~ 2.3 * (b + 1) = 4.6*loadav + 2.3 =~ 5*loadav. QED
*
* Actual power values for the implemented algorithm are as follows:
* loadav: 1 2 3 4
* power: 5.68 10.32 14.94 19.55
*/
/* calculations for digital decay to forget 90% of usage in 5*loadav sec */
#define loadfactor(loadav) (2 * (loadav))
#define decay_cpu(loadfac, cpu) (((loadfac) * (cpu)) / ((loadfac) + FSCALE))
/* decay 95% of `p_pctcpu' in 60 seconds; see CCPU_SHIFT before changing */
static fixpt_t ccpu = 0.95122942450071400909 * FSCALE; /* exp(-1/20) */
SYSCTL_INT(_kern, OID_AUTO, ccpu, CTLFLAG_RD, &ccpu, 0, "");
/* kernel uses `FSCALE', userland (SHOULD) use kern.fscale */
static int fscale __unused = FSCALE;
SYSCTL_INT(_kern, OID_AUTO, fscale, CTLFLAG_RD, 0, FSCALE, "");
/*
* If `ccpu' is not equal to `exp(-1/20)' and you still want to use the
* faster/more-accurate formula, you'll have to estimate CCPU_SHIFT below
* and possibly adjust FSHIFT in "param.h" so that (FSHIFT >= CCPU_SHIFT).
*
* To estimate CCPU_SHIFT for exp(-1/20), the following formula was used:
* 1 - exp(-1/20) ~= 0.0487 ~= 0.0488 == 1 (fixed pt, *11* bits).
*
* If you don't want to bother with the faster/more-accurate formula, you
* can set CCPU_SHIFT to (FSHIFT + 1) which will use a slower/less-accurate
* (more general) method of calculating the %age of CPU used by a process.
*/
#define CCPU_SHIFT 11
/*
* Recompute process priorities, every hz ticks.
*/
/* ARGSUSED */
static void
schedcpu(arg)
void *arg;
{
register fixpt_t loadfac = loadfactor(averunnable.ldavg[0]);
register struct proc *p;
register int realstathz, s;
realstathz = stathz ? stathz : hz;
LIST_FOREACH(p, &allproc, p_list) {
/*
* Increment time in/out of memory and sleep time
* (if sleeping). We ignore overflow; with 16-bit int's
* (remember them?) overflow takes 45 days.
*/
p->p_swtime++;
if (p->p_stat == SSLEEP || p->p_stat == SSTOP)
p->p_slptime++;
p->p_pctcpu = (p->p_pctcpu * ccpu) >> FSHIFT;
/*
* If the process has slept the entire second,
* stop recalculating its priority until it wakes up.
*/
if (p->p_slptime > 1)
continue;
s = splhigh(); /* prevent state changes and protect run queue */
/*
* p_pctcpu is only for ps.
*/
#if (FSHIFT >= CCPU_SHIFT)
p->p_pctcpu += (realstathz == 100)?
((fixpt_t) p->p_cpticks) << (FSHIFT - CCPU_SHIFT):
100 * (((fixpt_t) p->p_cpticks)
<< (FSHIFT - CCPU_SHIFT)) / realstathz;
#else
p->p_pctcpu += ((FSCALE - ccpu) *
(p->p_cpticks * FSCALE / realstathz)) >> FSHIFT;
#endif
p->p_cpticks = 0;
p->p_estcpu = decay_cpu(loadfac, p->p_estcpu);
resetpriority(p);
if (p->p_priority >= PUSER) {
if ((p != curproc) &&
#ifdef SMP
p->p_oncpu == 0xff && /* idle */
#endif
p->p_stat == SRUN &&
(p->p_flag & P_INMEM) &&
(p->p_priority / PPQ) != (p->p_usrpri / PPQ)) {
remrunqueue(p);
p->p_priority = p->p_usrpri;
setrunqueue(p);
} else
p->p_priority = p->p_usrpri;
}
splx(s);
}
vmmeter();
wakeup((caddr_t)&lbolt);
timeout(schedcpu, (void *)0, hz);
}
/*
* Recalculate the priority of a process after it has slept for a while.
* For all load averages >= 1 and max p_estcpu of 255, sleeping for at
* least six times the loadfactor will decay p_estcpu to zero.
*/
static void
updatepri(p)
register struct proc *p;
{
register unsigned int newcpu = p->p_estcpu;
register fixpt_t loadfac = loadfactor(averunnable.ldavg[0]);
if (p->p_slptime > 5 * loadfac)
p->p_estcpu = 0;
else {
p->p_slptime--; /* the first time was done in schedcpu */
while (newcpu && --p->p_slptime)
newcpu = decay_cpu(loadfac, newcpu);
p->p_estcpu = newcpu;
}
resetpriority(p);
}
/*
* We're only looking at 7 bits of the address; everything is
* aligned to 4, lots of things are aligned to greater powers
* of 2. Shift right by 8, i.e. drop the bottom 256 worth.
*/
#define TABLESIZE 128
static TAILQ_HEAD(slpquehead, proc) slpque[TABLESIZE];
#define LOOKUP(x) (((intptr_t)(x) >> 8) & (TABLESIZE - 1))
/*
* During autoconfiguration or after a panic, a sleep will simply
* lower the priority briefly to allow interrupts, then return.
* The priority to be used (safepri) is machine-dependent, thus this
* value is initialized and maintained in the machine-dependent layers.
* This priority will typically be 0, or the lowest priority
* that is safe for use on the interrupt stack; it can be made
* higher to block network software interrupts after panics.
*/
int safepri;
void
sleepinit(void)
{
int i;
sched_quantum = hz/10;
hogticks = 2 * sched_quantum;
for (i = 0; i < TABLESIZE; i++)
TAILQ_INIT(&slpque[i]);
}
/*
* General sleep call. Suspends the current process until a wakeup is
* performed on the specified identifier. The process will then be made
* runnable with the specified priority. Sleeps at most timo/hz seconds
* (0 means no timeout). If pri includes PCATCH flag, signals are checked
* before and after sleeping, else signals are not checked. Returns 0 if
* awakened, EWOULDBLOCK if the timeout expires. If PCATCH is set and a
* signal needs to be delivered, ERESTART is returned if the current system
* call should be restarted if possible, and EINTR is returned if the system
* call should be interrupted by the signal (return EINTR).
*/
int
tsleep(ident, priority, wmesg, timo)
void *ident;
int priority, timo;
const char *wmesg;
{
struct proc *p = curproc;
int s, sig, catch = priority & PCATCH;
struct callout_handle thandle;
#ifdef KTRACE
if (p && KTRPOINT(p, KTR_CSW))
ktrcsw(p->p_tracep, 1, 0);
#endif
s = splhigh();
if (cold || panicstr) {
/*
* After a panic, or during autoconfiguration,
* just give interrupts a chance, then just return;
* don't run any other procs or panic below,
* in case this is the idle process and already asleep.
*/
splx(safepri);
splx(s);
return (0);
}
KASSERT(p != NULL, ("tsleep1"));
KASSERT(ident != NULL && p->p_stat == SRUN, ("tsleep"));
/*
* Process may be sitting on a slpque if asleep() was called, remove
* it before re-adding.
*/
if (p->p_wchan != NULL)
unsleep(p);
p->p_wchan = ident;
p->p_wmesg = wmesg;
p->p_slptime = 0;
p->p_priority = priority & PRIMASK;
TAILQ_INSERT_TAIL(&slpque[LOOKUP(ident)], p, p_procq);
if (timo)
thandle = timeout(endtsleep, (void *)p, timo);
/*
* We put ourselves on the sleep queue and start our timeout
* before calling CURSIG, as we could stop there, and a wakeup
* 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.
*/
if (catch) {
p->p_flag |= P_SINTR;
if ((sig = CURSIG(p))) {
if (p->p_wchan)
unsleep(p);
p->p_stat = SRUN;
goto resume;
}
if (p->p_wchan == 0) {
catch = 0;
goto resume;
}
} else
sig = 0;
p->p_stat = SSLEEP;
p->p_stats->p_ru.ru_nvcsw++;
mi_switch();
resume:
curpriority = p->p_usrpri;
splx(s);
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->p_tracep, 0, 0);
#endif
return (EWOULDBLOCK);
}
} else if (timo)
untimeout(endtsleep, (void *)p, thandle);
if (catch && (sig != 0 || (sig = CURSIG(p)))) {
#ifdef KTRACE
if (KTRPOINT(p, KTR_CSW))
ktrcsw(p->p_tracep, 0, 0);
#endif
if (SIGISMEMBER(p->p_sigacts->ps_sigintr, sig))
return (EINTR);
return (ERESTART);
}
#ifdef KTRACE
if (KTRPOINT(p, KTR_CSW))
ktrcsw(p->p_tracep, 0, 0);
#endif
return (0);
}
/*
* asleep() - async sleep call. Place process on wait queue and return
* immediately without blocking. The process stays runnable until await()
* is called. If ident is NULL, remove process from wait queue if it is still
* on one.
*
* Only the most recent sleep condition is effective when making successive
* calls to asleep() or when calling tsleep().
*
* The timeout, if any, is not initiated until await() is called. The sleep
* priority, signal, and timeout is specified in the asleep() call but may be
* overriden in the await() call.
*
* <<<<<<<< EXPERIMENTAL, UNTESTED >>>>>>>>>>
*/
int
asleep(void *ident, int priority, const char *wmesg, int timo)
{
struct proc *p = curproc;
int s;
/*
* splhigh() while manipulating sleep structures and slpque.
*
* Remove preexisting wait condition (if any) and place process
* on appropriate slpque, but do not put process to sleep.
*/
s = splhigh();
if (p->p_wchan != NULL)
unsleep(p);
if (ident) {
p->p_wchan = ident;
p->p_wmesg = wmesg;
p->p_slptime = 0;
p->p_asleep.as_priority = priority;
p->p_asleep.as_timo = timo;
TAILQ_INSERT_TAIL(&slpque[LOOKUP(ident)], p, p_procq);
}
splx(s);
return(0);
}
/*
* await() - wait for async condition to occur. The process blocks until
* wakeup() is called on the most recent asleep() address. If wakeup is called
* priority to await(), await() winds up being a NOP.
*
* If await() is called more then once (without an intervening asleep() call),
* await() is still effectively a NOP but it calls mi_switch() to give other
* processes some cpu before returning. The process is left runnable.
*
* <<<<<<<< EXPERIMENTAL, UNTESTED >>>>>>>>>>
*/
int
await(int priority, int timo)
{
struct proc *p = curproc;
int s;
s = splhigh();
if (p->p_wchan != NULL) {
struct callout_handle thandle;
int sig;
int catch;
/*
* The call to await() can override defaults specified in
* the original asleep().
*/
if (priority < 0)
priority = p->p_asleep.as_priority;
if (timo < 0)
timo = p->p_asleep.as_timo;
/*
* Install timeout
*/
if (timo)
thandle = timeout(endtsleep, (void *)p, timo);
sig = 0;
catch = priority & PCATCH;
if (catch) {
p->p_flag |= P_SINTR;
if ((sig = CURSIG(p))) {
if (p->p_wchan)
unsleep(p);
p->p_stat = SRUN;
goto resume;
}
if (p->p_wchan == NULL) {
catch = 0;
goto resume;
}
}
p->p_stat = SSLEEP;
p->p_stats->p_ru.ru_nvcsw++;
mi_switch();
resume:
curpriority = p->p_usrpri;
splx(s);
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->p_tracep, 0, 0);
#endif
return (EWOULDBLOCK);
}
} else if (timo)
untimeout(endtsleep, (void *)p, thandle);
if (catch && (sig != 0 || (sig = CURSIG(p)))) {
#ifdef KTRACE
if (KTRPOINT(p, KTR_CSW))
ktrcsw(p->p_tracep, 0, 0);
#endif
if (SIGISMEMBER(p->p_sigacts->ps_sigintr, sig))
return (EINTR);
return (ERESTART);
}
#ifdef KTRACE
if (KTRPOINT(p, KTR_CSW))
ktrcsw(p->p_tracep, 0, 0);
#endif
} else {
/*
* If as_priority is 0, await() has been called without an
* intervening asleep(). We are still effectively a NOP,
* but we call mi_switch() for safety.
*/
if (p->p_asleep.as_priority == 0) {
p->p_stats->p_ru.ru_nvcsw++;
mi_switch();
}
splx(s);
}
/*
* clear p_asleep.as_priority as an indication that await() has been
* called. If await() is called again without an intervening asleep(),
* await() is still effectively a NOP but the above mi_switch() code
* is triggered as a safety.
*/
p->p_asleep.as_priority = 0;
return (0);
}
/*
* Implement timeout for tsleep or asleep()/await()
*
* 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.
*/
static void
endtsleep(arg)
void *arg;
{
register struct proc *p;
int s;
p = (struct proc *)arg;
s = splhigh();
if (p->p_wchan) {
if (p->p_stat == SSLEEP)
setrunnable(p);
else
unsleep(p);
p->p_flag |= P_TIMEOUT;
}
splx(s);
}
/*
* Remove a process from its wait queue
*/
void
unsleep(p)
register struct proc *p;
{
int s;
s = splhigh();
if (p->p_wchan) {
TAILQ_REMOVE(&slpque[LOOKUP(p->p_wchan)], p, p_procq);
p->p_wchan = 0;
}
splx(s);
}
/*
* Make all processes sleeping on the specified identifier runnable.
*/
void
wakeup(ident)
register void *ident;
{
register struct slpquehead *qp;
register struct proc *p;
int s;
s = splhigh();
qp = &slpque[LOOKUP(ident)];
restart:
TAILQ_FOREACH(p, qp, p_procq) {
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);
maybe_resched(p);
} else {
p->p_flag |= P_SWAPINREQ;
wakeup((caddr_t)&proc0);
}
/* END INLINE EXPANSION */
goto restart;
}
}
}
splx(s);
}
/*
* Make a process sleeping on the specified identifier runnable.
* May wake more than one process if a target prcoess is currently
* swapped out.
*/
void
wakeup_one(ident)
register void *ident;
{
register struct slpquehead *qp;
register struct proc *p;
int s;
s = splhigh();
qp = &slpque[LOOKUP(ident)];
TAILQ_FOREACH(p, qp, p_procq) {
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);
maybe_resched(p);
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()
{
struct timeval new_switchtime;
register struct proc *p = curproc; /* XXX */
register struct rlimit *rlim;
int x;
/*
* 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\n");
#endif
/*
* 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, &switchtime, <)) {
printf("microuptime() went backwards (%ld.%06ld -> %ld,%06ld)\n",
switchtime.tv_sec, switchtime.tv_usec,
new_switchtime.tv_sec, new_switchtime.tv_usec);
new_switchtime = switchtime;
} else {
p->p_runtime += (new_switchtime.tv_usec - switchtime.tv_usec) +
(new_switchtime.tv_sec - switchtime.tv_sec) * (int64_t)1000000;
}
/*
* Check if the process exceeds its cpu resource allocation.
* If over max, kill it.
*/
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) {
killproc(p, "exceeded maximum CPU limit");
} else {
psignal(p, SIGXCPU);
if (rlim->rlim_cur < rlim->rlim_max) {
/* XXX: we should make a private copy */
rlim->rlim_cur += 5;
}
}
}
/*
* Pick a new current process and record its start time.
*/
cnt.v_swtch++;
switchtime = new_switchtime;
cpu_switch(p);
if (switchtime.tv_sec == 0)
microuptime(&switchtime);
switchticks = ticks;
splx(x);
}
/*
* 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
maybe_resched(p);
}
/*
* 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 / INVERSE_ESTCPU_WEIGHT +
NICE_WEIGHT * p->p_nice;
newpriority = min(newpriority, MAXPRI);
p->p_usrpri = newpriority;
}
maybe_resched(p);
}
/* ARGSUSED */
static void
sched_setup(dummy)
void *dummy;
{
/* 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_priority >= PUSER)
p->p_priority = p->p_usrpri;
}
}
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