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[unix-history] / usr / src / sys / kern / kern_clock.c
/* kern_clock.c 4.31 82/06/26 */
#include "../h/param.h"
#include "../h/systm.h"
#include "../h/dk.h"
#include "../h/callout.h"
#include "../h/seg.h"
#include "../h/dir.h"
#include "../h/user.h"
#include "../h/proc.h"
#include "../h/reg.h"
#include "../h/psl.h"
#include "../h/vm.h"
#include "../h/buf.h"
#include "../h/text.h"
#include "../h/vlimit.h"
#include "../h/mtpr.h"
#include "../h/clock.h"
#include "../h/cpu.h"
#include "../h/protosw.h"
#include "bk.h"
#include "dh.h"
#include "dz.h"
#include "ps.h"
/*
* Hardclock is called straight from
* the real time clock interrupt.
* We limit the work we do at real clock interrupt time to:
* reloading clock
* decrementing time to callouts
* recording cpu time usage
* modifying priority of current process
* arrange for soft clock interrupt
* kernel pc profiling
*
* At software (softclock) interrupt time we:
* implement callouts
* maintain date
* lightning bolt wakeup (every second)
* alarm clock signals
* jab the scheduler
*
* On the vax softclock interrupts are implemented by
* software interrupts. Note that we may have multiple softclock
* interrupts compressed into one (due to excessive interrupt load),
* but that hardclock interrupts should never be lost.
*/
#ifdef KPROF
int kcounts[20000];
#endif
/*
* Protoslow is like lbolt, but for slow protocol timeouts, counting
* up to (hz/PR_SLOWHZ), then causing a pfslowtimo().
* Protofast is like lbolt, but for fast protocol timeouts, counting
* up to (hz/PR_FASTHZ), then causing a pffasttimo().
*/
int protoslow;
int protofast;
/*ARGSUSED*/
hardclock(pc, ps)
caddr_t pc;
{
register struct callout *p1;
register struct proc *pp;
register int s, cpstate;
/*
* reprime clock
*/
clkreld();
#if NPS > 0
/*
* sync referesh of picture system
*/
psextsync(pc, ps);
#endif
/*
* update callout times
*/
for (p1 = calltodo.c_next; p1 && p1->c_time <= 0; p1 = p1->c_next)
;
if (p1)
p1->c_time--;
/*
* Maintain iostat and per-process cpu statistics
*/
if (!noproc) {
s = u.u_procp->p_rssize;
u.u_vm.vm_idsrss += s;
if (u.u_procp->p_textp) {
register int xrss = u.u_procp->p_textp->x_rssize;
s += xrss;
u.u_vm.vm_ixrss += xrss;
}
if (s > u.u_vm.vm_maxrss)
u.u_vm.vm_maxrss = s;
if ((u.u_vm.vm_utime+u.u_vm.vm_stime+1)/hz > u.u_limit[LIM_CPU]) {
psignal(u.u_procp, SIGXCPU);
if (u.u_limit[LIM_CPU] < INFINITY - 5)
u.u_limit[LIM_CPU] += 5;
}
}
/*
* Update iostat information.
*/
if (USERMODE(ps)) {
u.u_vm.vm_utime++;
if(u.u_procp->p_nice > NZERO)
cpstate = CP_NICE;
else
cpstate = CP_USER;
} else {
#ifdef KPROF
int k = ((int)pc & 0x7fffffff) / 8;
if (k < 20000)
kcounts[k]++;
#endif
cpstate = CP_SYS;
if (noproc)
cpstate = CP_IDLE;
else
u.u_vm.vm_stime++;
}
cp_time[cpstate]++;
for (s = 0; s < DK_NDRIVE; s++)
if (dk_busy&(1<<s))
dk_time[s]++;
/*
* Adjust priority of current process.
*/
if (!noproc) {
pp = u.u_procp;
pp->p_cpticks++;
if(++pp->p_cpu == 0)
pp->p_cpu--;
if(pp->p_cpu % 4 == 0) {
(void) setpri(pp);
if (pp->p_pri >= PUSER)
pp->p_pri = pp->p_usrpri;
}
}
/*
* Time moves on.
*/
++lbolt;
/*
* Time moves on for protocols.
*/
--protoslow; --protofast;
#if VAX780
/*
* On 780's, impelement a fast UBA watcher,
* to make sure uba's don't get stuck.
*/
if (cpu == VAX_780 && panicstr == 0 && !BASEPRI(ps))
unhang();
#endif
/*
* Schedule a software interrupt for the rest
* of clock activities.
*/
setsoftclock();
}
/*
* The digital decay cpu usage priority assignment is scaled to run in
* time as expanded by the 1 minute load average. Each second we
* multiply the the previous cpu usage estimate by
* nrscale*avenrun[0]
* The following relates the load average to the period over which
* cpu usage is 90% forgotten:
* loadav 1 5 seconds
* loadav 5 24 seconds
* loadav 10 47 seconds
* loadav 20 93 seconds
* This is a great improvement on the previous algorithm which
* decayed the priorities by a constant, and decayed away all knowledge
* of previous activity in about 20 seconds. Under heavy load,
* the previous algorithm degenerated to round-robin with poor response
* time when there was a high load average.
*/
#undef ave
#define ave(a,b) ((int)(((int)(a*b))/(b+1)))
int nrscale = 2;
double avenrun[];
/*
* Constant for decay filter for cpu usage field
* in process table (used by ps au).
*/
double ccpu = 0.95122942450071400909; /* exp(-1/20) */
/*
* Software clock interrupt.
* This routine runs at lower priority than device interrupts.
*/
/*ARGSUSED*/
softclock(pc, ps)
caddr_t pc;
{
register struct callout *p1;
register struct proc *pp;
register int a, s;
caddr_t arg;
int (*func)();
/*
* Perform callouts (but not after panic's!)
*/
if (panicstr == 0) {
for (;;) {
s = spl7();
if ((p1 = calltodo.c_next) == 0 || p1->c_time > 0) {
splx(s);
break;
}
calltodo.c_next = p1->c_next;
arg = p1->c_arg;
func = p1->c_func;
p1->c_next = callfree;
callfree = p1;
(void) splx(s);
(*func)(arg);
}
}
/*
* Drain silos.
*/
#if NDH > 0
s = spl5(); dhtimer(); splx(s);
#endif
#if NDZ > 0
s = spl5(); dztimer(); splx(s);
#endif
/*
* If idling and processes are waiting to swap in,
* check on them.
*/
if (noproc && runin) {
runin = 0;
wakeup((caddr_t)&runin);
}
/*
* Run paging daemon every 1/4 sec.
*/
if (lbolt % (hz/4) == 0) {
vmpago();
}
/*
* Reschedule every 1/10 sec.
*/
if (lbolt % (hz/10) == 0) {
runrun++;
aston();
}
/*
* Run network slow and fast timeouts.
*/
if (protofast <= 0) {
protofast = hz / PR_FASTHZ;
pffasttimo();
}
if (protoslow <= 0) {
protoslow = hz / PR_SLOWHZ;
pfslowtimo();
}
/*
* Lightning bolt every second:
* sleep timeouts
* process priority recomputation
* process %cpu averaging
* virtual memory metering
* kick swapper if processes want in
*/
if (lbolt >= hz) {
/*
* This doesn't mean much on VAX since we run at
* software interrupt time... if hardclock()
* calls softclock() directly, it prevents
* this code from running when the priority
* was raised when the clock interrupt occurred.
*/
if (BASEPRI(ps))
return;
/*
* If we didn't run a few times because of
* long blockage at high ipl, we don't
* really want to run this code several times,
* so squish out all multiples of hz here.
*/
time += lbolt / hz;
lbolt %= hz;
/*
* Wakeup lightning bolt sleepers.
* Processes sleep on lbolt to wait
* for short amounts of time (e.g. 1 second).
*/
wakeup((caddr_t)&lbolt);
/*
* Recompute process priority and process
* sleep() system calls as well as internal
* sleeps with timeouts (tsleep() kernel routine).
*/
for (pp = proc; pp < procNPROC; pp++)
if (pp->p_stat && pp->p_stat!=SZOMB) {
/*
* Increase resident time, to max of 127 seconds
* (it is kept in a character.) For
* loaded processes this is time in core; for
* swapped processes, this is time on drum.
*/
if (pp->p_time != 127)
pp->p_time++;
/*
* If process has clock counting down, and it
* expires, set it running (if this is a tsleep()),
* or give it an SIGALRM (if the user process
* is using alarm signals.
*/
if (pp->p_clktim && --pp->p_clktim == 0)
if (pp->p_flag & STIMO) {
s = spl6();
switch (pp->p_stat) {
case SSLEEP:
setrun(pp);
break;
case SSTOP:
unsleep(pp);
break;
}
pp->p_flag &= ~STIMO;
splx(s);
} else
psignal(pp, SIGALRM);
/*
* If process is blocked, increment computed
* time blocked. This is used in swap scheduling.
*/
if (pp->p_stat==SSLEEP || pp->p_stat==SSTOP)
if (pp->p_slptime != 127)
pp->p_slptime++;
/*
* Update digital filter estimation of process
* cpu utilization for loaded processes.
*/
if (pp->p_flag&SLOAD)
pp->p_pctcpu = ccpu * pp->p_pctcpu +
(1.0 - ccpu) * (pp->p_cpticks/(float)hz);
/*
* Recompute process priority. The number p_cpu
* is a weighted estimate of cpu time consumed.
* A process which consumes cpu time has this
* increase regularly. We here decrease it by
* a fraction based on load average giving a digital
* decay filter which damps out in about 5 seconds
* when seconds are measured in time expanded by the
* load average.
*
* If a process is niced, then the nice directly
* affects the new priority. The final priority
* is in the range 0 to 255, to fit in a character.
*/
pp->p_cpticks = 0;
a = ave((pp->p_cpu & 0377), avenrun[0]*nrscale) +
pp->p_nice - NZERO;
if (a < 0)
a = 0;
if (a > 255)
a = 255;
pp->p_cpu = a;
(void) setpri(pp);
/*
* Now have computed new process priority
* in p->p_usrpri. Carefully change p->p_pri.
* A process is on a run queue associated with
* this priority, so we must block out process
* state changes during the transition.
*/
s = spl6();
if (pp->p_pri >= PUSER) {
if ((pp != u.u_procp || noproc) &&
pp->p_stat == SRUN &&
(pp->p_flag & SLOAD) &&
pp->p_pri != pp->p_usrpri) {
remrq(pp);
pp->p_pri = pp->p_usrpri;
setrq(pp);
} else
pp->p_pri = pp->p_usrpri;
}
splx(s);
}
/*
* Perform virtual memory metering.
*/
vmmeter();
/*
* If the swap process is trying to bring
* a process in, have it look again to see
* if it is possible now.
*/
if (runin!=0) {
runin = 0;
wakeup((caddr_t)&runin);
}
/*
* If there are pages that have been cleaned,
* jolt the pageout daemon to process them.
* We do this here so that these pages will be
* freed if there is an abundance of memory and the
* daemon would not be awakened otherwise.
*/
if (bclnlist != NULL)
wakeup((caddr_t)&proc[2]);
/*
* If the trap occurred from usermode,
* then check to see if it has now been
* running more than 10 minutes of user time
* and should thus run with reduced priority
* to give other processes a chance.
*/
if (USERMODE(ps)) {
pp = u.u_procp;
if (pp->p_uid && pp->p_nice == NZERO &&
u.u_vm.vm_utime > 600 * hz)
pp->p_nice = NZERO+4;
(void) setpri(pp);
pp->p_pri = pp->p_usrpri;
}
}
/*
* If trapped user-mode, give it a profiling tick.
*/
if (USERMODE(ps) && u.u_prof.pr_scale) {
u.u_procp->p_flag |= SOWEUPC;
aston();
}
}
/*
* Timeout is called to arrange that
* fun(arg) is called in tim/hz seconds.
* An entry is linked into the callout
* structure. The time in each structure
* entry is the number of hz's more
* than the previous entry.
* In this way, decrementing the
* first entry has the effect of
* updating all entries.
*
* The panic is there because there is nothing
* intelligent to be done if an entry won't fit.
*/
timeout(fun, arg, tim)
int (*fun)();
caddr_t arg;
{
register struct callout *p1, *p2, *pnew;
register int t;
int s;
/* DEBUGGING CODE */
int ttrstrt();
if (fun == ttrstrt && arg == 0)
panic("timeout ttrstr arg");
/* END DEBUGGING CODE */
t = tim;
s = spl7();
pnew = callfree;
if (pnew == NULL)
panic("timeout table overflow");
callfree = pnew->c_next;
pnew->c_arg = arg;
pnew->c_func = fun;
for (p1 = &calltodo; (p2 = p1->c_next) && p2->c_time < t; p1 = p2)
t -= p2->c_time;
p1->c_next = pnew;
pnew->c_next = p2;
pnew->c_time = t;
if (p2)
p2->c_time -= t;
splx(s);
}
/*
* untimeout is called to remove a function timeout call
* from the callout structure.
*/
untimeout (fun, arg)
int (*fun)();
caddr_t arg;
{
register struct callout *p1, *p2;
register int s;
s = spl7();
for (p1 = &calltodo; (p2 = p1->c_next) != 0; p1 = p2) {
if (p2->c_func == fun && p2->c_arg == arg) {
if (p2->c_next)
p2->c_next->c_time += p2->c_time;
p1->c_next = p2->c_next;
p2->c_next = callfree;
callfree = p2;
break;
}
}
splx(s);
}
Continuous source code history from original PDP-7 UNIX to FreeBSD 2, the first fully unencumbered FreeBSD release.