/*-
* 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: src/sys/kern/kern_synch.c,v 1.87.2.6 2002/10/13 07:29:53 kbyanc Exp $
* $DragonFly: src/sys/kern/kern_synch.c,v 1.20 2003/08/03 10:07:41 hmp Exp $
*/
#include "opt_ktrace.h"
#include
#include
#include
#include
#include
#include
#include
#include
#include
#ifdef KTRACE
#include
#include
#endif
#include
#include
#include
#include
static void sched_setup __P((void *dummy));
SYSINIT(sched_setup, SI_SUB_KICK_SCHEDULER, SI_ORDER_FIRST, sched_setup, NULL)
int hogticks;
int lbolt;
int sched_quantum; /* Roundrobin scheduling quantum in ticks. */
int ncpus;
static struct callout loadav_callout;
struct loadavg averunnable =
{ {0, 0, 0}, FSCALE }; /* load average, of runnable procs */
/*
* Constants for averages over 1, 5, and 15 minutes
* when sampling at 5 second intervals.
*/
static fixpt_t cexp[3] = {
0.9200444146293232 * FSCALE, /* exp(-1/12) */
0.9834714538216174 * FSCALE, /* exp(-1/60) */
0.9944598480048967 * FSCALE, /* exp(-1/180) */
};
static void endtsleep __P((void *));
static void loadav __P((void *arg));
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 void crit_panicints(void);
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", "");
/*
* Arrange to reschedule if necessary by checking to see if the current
* process is on the highest priority user scheduling queue. This may
* be run from an interrupt so we have to follow any preemption chains
* back to the original process.
*/
static void
maybe_resched(struct proc *chk)
{
struct proc *cur = lwkt_preempted_proc();
if (cur == NULL)
return;
/*
* Check the user queue (realtime, normal, idle). Lower numbers
* indicate higher priority queues. Lower numbers are also better
* for p_priority.
*/
if (chk->p_rtprio.type < cur->p_rtprio.type) {
need_resched();
} else if (chk->p_rtprio.type == cur->p_rtprio.type) {
if (chk->p_rtprio.type == RTP_PRIO_NORMAL) {
if (chk->p_priority / PPQ < cur->p_priority / PPQ)
need_resched();
} else {
if (chk->p_rtprio.prio < cur->p_rtprio.prio)
need_resched();
}
}
}
int
roundrobin_interval(void)
{
return (sched_quantum);
}
/*
* Force switch among equal priority processes every 100ms.
*/
#ifdef SMP
static void
roundrobin_remote(void *arg)
{
struct proc *p = lwkt_preempted_proc();
if (p == NULL || RTP_PRIO_NEED_RR(p->p_rtprio.type))
need_resched();
}
#endif
static void
roundrobin(void *arg)
{
struct proc *p = lwkt_preempted_proc();
if (p == NULL || RTP_PRIO_NEED_RR(p->p_rtprio.type))
need_resched();
#ifdef SMP
lwkt_send_ipiq_mask(mycpu->gd_other_cpus, roundrobin_remote, NULL);
#endif
timeout(roundrobin, NULL, sched_quantum);
}
#ifdef SMP
void
resched_cpus(u_int32_t mask)
{
lwkt_send_ipiq_mask(mask, roundrobin_remote, NULL);
}
#endif
/*
* 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(void *arg)
{
fixpt_t loadfac = loadfactor(averunnable.ldavg[0]);
struct proc *p;
struct proc *curp;
int realstathz, s;
curp = lwkt_preempted_proc(); /* YYY temporary hack */
realstathz = stathz ? stathz : hz;
FOREACH_PROC_IN_SYSTEM(p) {
/*
* 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);
splx(s);
}
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(struct proc *p)
{
unsigned int newcpu = p->p_estcpu;
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, thread) 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 flags 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).
*
* If the process has P_CURPROC set mi_switch() will not re-queue it to
* the userland scheduler queues because we are in a SSLEEP state. If
* we are not the current process then we have to remove ourselves from
* the scheduler queues.
*
* YYY priority now unused
*/
int
tsleep(ident, flags, wmesg, timo)
void *ident;
int flags, timo;
const char *wmesg;
{
struct thread *td = curthread;
struct proc *p = td->td_proc; /* may be NULL */
int s, sig = 0, catch = flags & PCATCH;
int id = LOOKUP(ident);
struct callout_handle thandle;
/*
* NOTE: removed KTRPOINT, it could cause races due to blocking
* even in stable. Just scrap it for now.
*/
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.
*/
crit_panicints();
return (0);
}
KKASSERT(td != &mycpu->gd_idlethread); /* you must be kidding! */
s = splhigh();
KASSERT(ident != NULL, ("tsleep: no ident"));
KASSERT(p == NULL || p->p_stat == SRUN, ("tsleep %p %s %d",
ident, wmesg, p->p_stat));
crit_enter();
td->td_wchan = ident;
td->td_wmesg = wmesg;
if (p)
p->p_slptime = 0;
lwkt_deschedule_self();
TAILQ_INSERT_TAIL(&slpque[id], td, td_threadq);
if (timo)
thandle = timeout(endtsleep, (void *)td, 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, td->td_wchan will be 0 upon return from CURSIG.
*/
if (p) {
if (catch) {
p->p_flag |= P_SINTR;
if ((sig = CURSIG(p))) {
if (td->td_wchan) {
unsleep(td);
lwkt_schedule_self();
}
p->p_stat = SRUN;
goto resume;
}
if (td->td_wchan == NULL) {
catch = 0;
goto resume;
}
} else {
sig = 0;
}
/*
* If we are not the current process we have to remove ourself
* from the run queue.
*/
KASSERT(p->p_stat == SRUN, ("PSTAT NOT SRUN %d %d", p->p_pid, p->p_stat));
/*
* If this is the current 'user' process schedule another one.
*/
clrrunnable(p, SSLEEP);
p->p_stats->p_ru.ru_nvcsw++;
KKASSERT(td->td_release || (p->p_flag & P_CURPROC) == 0);
mi_switch();
KASSERT(p->p_stat == SRUN, ("tsleep: stat not srun"));
} else {
lwkt_switch();
}
resume:
crit_exit();
if (p)
p->p_flag &= ~P_SINTR;
splx(s);
if (td->td_flags & TDF_TIMEOUT) {
td->td_flags &= ~TDF_TIMEOUT;
if (sig == 0)
return (EWOULDBLOCK);
} else if (timo) {
untimeout(endtsleep, (void *)td, thandle);
}
if (p) {
if (catch && (sig != 0 || (sig = CURSIG(p)))) {
if (SIGISMEMBER(p->p_sigacts->ps_sigintr, sig))
return (EINTR);
return (ERESTART);
}
}
return (0);
}
/*
* Implement the timeout for tsleep. We interlock against
* wchan when setting TDF_TIMEOUT. For processes we remove
* the sleep if the process is stopped rather then sleeping,
* so it remains stopped.
*/
static void
endtsleep(void *arg)
{
thread_t td = arg;
struct proc *p;
int s;
s = splhigh();
if (td->td_wchan) {
td->td_flags |= TDF_TIMEOUT;
if ((p = td->td_proc) != NULL) {
if (p->p_stat == SSLEEP)
setrunnable(p);
else
unsleep(td);
} else {
unsleep(td);
lwkt_schedule(td);
}
}
splx(s);
}
/*
* Remove a process from its wait queue
*/
void
unsleep(struct thread *td)
{
int s;
s = splhigh();
if (td->td_wchan) {
#if 0
if (p->p_flag & P_XSLEEP) {
struct xwait *w = p->p_wchan;
TAILQ_REMOVE(&w->waitq, p, p_procq);
p->p_flag &= ~P_XSLEEP;
} else
#endif
TAILQ_REMOVE(&slpque[LOOKUP(td->td_wchan)], td, td_threadq);
td->td_wchan = NULL;
}
splx(s);
}
#if 0
/*
* Make all processes sleeping on the explicit lock structure runnable.
*/
void
xwakeup(struct xwait *w)
{
struct proc *p;
int s;
s = splhigh();
++w->gen;
while ((p = TAILQ_FIRST(&w->waitq)) != NULL) {
TAILQ_REMOVE(&w->waitq, p, p_procq);
KASSERT(p->p_wchan == w && (p->p_flag & P_XSLEEP),
("xwakeup: wchan mismatch for %p (%p/%p) %08x", p, p->p_wchan, w, p->p_flag & P_XSLEEP));
p->p_wchan = NULL;
p->p_flag &= ~P_XSLEEP;
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);
}
}
}
splx(s);
}
#endif
/*
* Make all processes sleeping on the specified identifier runnable.
*/
static void
_wakeup(void *ident, int count)
{
struct slpquehead *qp;
struct thread *td;
struct thread *ntd;
struct proc *p;
int s;
int id = LOOKUP(ident);
s = splhigh();
qp = &slpque[id];
restart:
for (td = TAILQ_FIRST(qp); td != NULL; td = ntd) {
ntd = TAILQ_NEXT(td, td_threadq);
if (td->td_wchan == ident) {
TAILQ_REMOVE(qp, td, td_threadq);
td->td_wchan = NULL;
if ((p = td->td_proc) != NULL && 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);
if (p->p_flag & P_CURPROC)
maybe_resched(p);
} else {
p->p_flag |= P_SWAPINREQ;
wakeup((caddr_t)&proc0);
}
/* END INLINE EXPANSION */
} else if (p == NULL) {
lwkt_schedule(td);
}
if (--count == 0)
break;
goto restart;
}
}
splx(s);
}
void
wakeup(void *ident)
{
_wakeup(ident, 0);
}
void
wakeup_one(void *ident)
{
_wakeup(ident, 1);
}
/*
* The machine independent parts of mi_switch().
* Must be called at splstatclock() or higher.
*/
void
mi_switch()
{
struct thread *td = curthread;
struct proc *p = td->td_proc; /* XXX */
struct rlimit *rlim;
int x;
u_int64_t ttime;
/*
* 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();
clear_resched();
/*
* Check if the process exceeds its cpu resource allocation.
* If over max, kill it. Time spent in interrupts is not
* included. YYY 64 bit match is expensive. Ick.
*/
ttime = td->td_sticks + td->td_uticks;
if (p->p_stat != SZOMB && p->p_limit->p_cpulimit != RLIM_INFINITY &&
ttime > p->p_limit->p_cpulimit) {
rlim = &p->p_rlimit[RLIMIT_CPU];
if (ttime / (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. If we
* are in a SSTOPped state we deschedule ourselves. YYY this needs
* to be cleaned up, remember that LWKTs stay on their run queue
* which works differently then the user scheduler which removes
* the process from the runq when it runs it.
*/
mycpu->gd_cnt.v_swtch++;
if (p->p_stat == SSTOP)
lwkt_deschedule_self();
lwkt_switch();
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(struct proc *p)
{
int s;
s = splhigh();
switch (p->p_stat) {
case 0:
case SRUN:
case SZOMB:
default:
panic("setrunnable");
case SSTOP:
case SSLEEP:
unsleep(p->p_thread); /* 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);
}
}
/*
* Change the process state to NOT be runnable, removing it from the run
* queue. If P_CURPROC is not set and we are in SRUN the process is on the
* run queue (If P_INMEM is not set then it isn't because it is swapped).
*/
void
clrrunnable(struct proc *p, int stat)
{
int s;
s = splhigh();
switch(p->p_stat) {
case SRUN:
if (p->p_flag & P_ONRUNQ)
remrunqueue(p);
break;
default:
break;
}
p->p_stat = stat;
splx(s);
}
/*
* 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.
*
* YYY real time / idle procs do not use p_priority XXX
*/
void
resetpriority(struct proc *p)
{
unsigned int newpriority;
int opq;
int npq;
if (p->p_rtprio.type != RTP_PRIO_NORMAL)
return;
newpriority = PUSER + p->p_estcpu / INVERSE_ESTCPU_WEIGHT +
NICE_WEIGHT * p->p_nice;
newpriority = min(newpriority, MAXPRI);
npq = newpriority / PPQ;
crit_enter();
opq = p->p_priority / PPQ;
if (p->p_stat == SRUN && (p->p_flag & P_ONRUNQ) && opq != npq) {
/*
* We have to move the process to another queue
*/
remrunqueue(p);
p->p_priority = newpriority;
setrunqueue(p);
} else {
/*
* We can just adjust the priority and it will be picked
* up later.
*/
KKASSERT(opq == npq || (p->p_flag & P_ONRUNQ) == 0);
p->p_priority = newpriority;
}
crit_exit();
maybe_resched(p);
}
/*
* Compute a tenex style load average of a quantity on
* 1, 5 and 15 minute intervals.
*/
static void
loadav(void *arg)
{
int i, nrun;
struct loadavg *avg;
struct proc *p;
avg = &averunnable;
nrun = 0;
FOREACH_PROC_IN_SYSTEM(p) {
switch (p->p_stat) {
case SRUN:
case SIDL:
nrun++;
}
}
for (i = 0; i < 3; i++)
avg->ldavg[i] = (cexp[i] * avg->ldavg[i] +
nrun * FSCALE * (FSCALE - cexp[i])) >> FSHIFT;
/*
* Schedule the next update to occur after 5 seconds, but add a
* random variation to avoid synchronisation with processes that
* run at regular intervals.
*/
callout_reset(&loadav_callout, hz * 4 + (int)(random() % (hz * 2 + 1)),
loadav, NULL);
}
/* ARGSUSED */
static void
sched_setup(dummy)
void *dummy;
{
callout_init(&loadav_callout);
/* Kick off timeout driven events by calling first time. */
roundrobin(NULL);
schedcpu(NULL);
loadav(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);
}
static
void
crit_panicints(void)
{
int s;
int cpri;
s = splhigh();
cpri = crit_panic_save();
splx(safepri);
crit_panic_restore(cpri);
splx(s);
}