4.1cBSD/a/sys/sys/kern_clock.c
/* kern_clock.c 4.52 83/03/03 */
#include "../machine/reg.h"
#include "../machine/psl.h"
#include "../h/param.h"
#include "../h/systm.h"
#include "../h/dk.h"
#include "../h/callout.h"
#include "../h/dir.h"
#include "../h/user.h"
#include "../h/kernel.h"
#include "../h/proc.h"
#include "../h/vm.h"
#include "../h/text.h"
#ifdef MUSH
#include "../h/quota.h"
#include "../h/share.h"
#endif
#ifdef vax
#include "../vax/mtpr.h"
#endif
#ifdef GPROF
#include "../h/gprof.h"
#endif
#ifdef KGCLOCK
extern int phz;
#endif
/*
* Clock handling routines.
*
* This code is written to operate with two timers which run
* independently of each other. The main clock, running at hz
* times per second, is used to do scheduling and timeout calculations.
* The second timer does resource utilization estimation statistically
* based on the state of the machine phz times a second. Both functions
* can be performed by a single clock (ie hz == phz), however the
* statistics will be much more prone to errors. Ideally a machine
* would have separate clocks measuring time spent in user state, system
* state, interrupt state, and idle state. These clocks would allow a non-
* approximate measure of resource utilization.
*/
/*
* TODO:
* * Keep more accurate statistics by simulating good interval timers.
* * Use the time-of-day clock on the VAX to keep more accurate time
* than is possible by repeated use of the interval timer.
* * Allocate more timeout table slots when table overflows.
* * Get all resource allocation to use second timer.
*/
/* bump a timeval by a small number of usec's */
#define bumptime(tp, usec) \
(tp)->tv_usec += usec; \
if ((tp)->tv_usec >= 1000000) { \
(tp)->tv_usec -= 1000000; \
(tp)->tv_sec++; \
}
/*
* The hz hardware interval timer.
* We update the events relating to real time.
* If this timer is also being used to gather statistics,
* we run through the statistics gathering routine as well.
*/
/*ARGSUSED*/
#ifdef vax
hardclock(pc, ps)
caddr_t pc;
int ps;
{
#endif
#ifdef sun
hardclock(regs)
struct regs regs;
{
int ps = regs.r_sr;
caddr_t pc = (caddr_t)regs.r_pc;
#endif
register struct callout *p1;
register struct proc *p;
register int s, cpstate;
#ifdef sun
if (USERMODE(ps)) /* aston needs ar0 */
u.u_ar0 = ®s.r_r0;
#endif
/*
* Update real-time timeout queue.
* At front of queue are some number of events which are ``due''.
* The time to these is <= 0 and if negative represents the
* number of ticks which have passed since it was supposed to happen.
* The rest of the q elements (times > 0) are events yet to happen,
* where the time for each is given as a delta from the previous.
* Decrementing just the first of these serves to decrement the time
* to all events.
*/
for (p1 = calltodo.c_next; p1 && p1->c_time <= 0; p1 = p1->c_next)
--p1->c_time;
if (p1)
--p1->c_time;
/*
* Charge the time out based on the mode the cpu is in.
* Here again we fudge for the lack of proper interval timers
* assuming that the current state has been around at least
* one tick.
*/
if (USERMODE(ps)) {
/*
* CPU was in user state. Increment
* user time counter, and process process-virtual time
* interval timer.
*/
bumptime(&u.u_ru.ru_utime, tick);
if (timerisset(&u.u_timer[ITIMER_VIRTUAL].it_value) &&
itimerdecr(&u.u_timer[ITIMER_VIRTUAL], tick) == 0)
psignal(u.u_procp, SIGVTALRM);
if (u.u_procp->p_nice > NZERO)
cpstate = CP_NICE;
else
cpstate = CP_USER;
} else {
/*
* CPU was in system state. If profiling kernel
* increment a counter. If no process is running
* then this is a system tick if we were running
* at a non-zero IPL (in a driver). If a process is running,
* then we charge it with system time even if we were
* at a non-zero IPL, since the system often runs
* this way during processing of system calls.
* This is approximate, but the lack of true interval
* timers makes doing anything else difficult.
*/
cpstate = CP_SYS;
if (noproc) {
if (BASEPRI(ps))
cpstate = CP_IDLE;
} else {
bumptime(&u.u_ru.ru_stime, tick);
}
}
/*
* If the cpu is currently scheduled to a process, then
* charge it with resource utilization for a tick, updating
* statistics which run in (user+system) virtual time,
* such as the cpu time limit and profiling timers.
* This assumes that the current process has been running
* the entire last tick.
*/
if (noproc == 0 && cpstate != CP_IDLE) {
if ((u.u_ru.ru_utime.tv_sec+u.u_ru.ru_stime.tv_sec+1) >
u.u_rlimit[RLIMIT_CPU].rlim_cur) {
psignal(u.u_procp, SIGXCPU);
if (u.u_rlimit[RLIMIT_CPU].rlim_cur <
u.u_rlimit[RLIMIT_CPU].rlim_max)
u.u_rlimit[RLIMIT_CPU].rlim_cur += 5;
}
if (timerisset(&u.u_timer[ITIMER_PROF].it_value) &&
itimerdecr(&u.u_timer[ITIMER_PROF], tick) == 0)
psignal(u.u_procp, SIGPROF);
s = u.u_procp->p_rssize;
u.u_ru.ru_idrss += s; u.u_ru.ru_isrss += 0; /* XXX */
if (u.u_procp->p_textp) {
register int xrss = u.u_procp->p_textp->x_rssize;
s += xrss;
u.u_ru.ru_ixrss += xrss;
}
if (s > u.u_ru.ru_maxrss)
u.u_ru.ru_maxrss = s;
}
/*
* 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_cpu) is increased here
* and the formula for computing priorities (in kern_synch.c)
* will compute a different value each time the p_cpu increases
* by 4. 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 principal is that the system will 90% forget
* that a 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.
*/
if (!noproc) {
p = u.u_procp;
p->p_cpticks++;
if (++p->p_cpu == 0)
p->p_cpu--;
#ifdef MUSH
p->p_quota->q_cost += (p->p_nice > NZERO ?
(shconsts.sc_tic * ((2*NZERO)-p->p_nice)) / NZERO :
shconsts.sc_tic) * (((int)avenrun[0]+2)/3);
#endif
if ((p->p_cpu&3) == 0) {
(void) setpri(p);
if (p->p_pri >= PUSER)
p->p_pri = p->p_usrpri;
}
}
/*
* If this is the only timer then we have to use it to
* gather statistics.
*/
#ifndef KGCLOCK
gatherstats(pc, ps);
#else
/*
* If the alternate clock has not made itself known then
* we must gather the statistics.
*/
if (phz == 0)
gatherstats(pc, ps);
#endif
/*
* Increment the time-of-day, and schedule
* processing of the callouts at a very low cpu priority,
* so we don't keep the relatively high clock interrupt
* priority any longer than necessary.
*/
bumptime(&time, tick);
setsoftclock();
}
/*
* Gather statistics on resource utilization.
*
* We make a gross assumption: that the system has been in the
* state it is in (user state, kernel state, interrupt state,
* or idle state) for the entire last time interval, and
* update statistics accordingly.
*/
gatherstats(pc, ps)
caddr_t pc;
int ps;
{
int cpstate, s;
/*
* Determine what state the cpu is in.
*/
if (USERMODE(ps)) {
/*
* CPU was in user state.
*/
if (u.u_procp->p_nice > NZERO)
cpstate = CP_NICE;
else
cpstate = CP_USER;
} else {
/*
* CPU was in system state. If profiling kernel
* increment a counter.
*/
cpstate = CP_SYS;
if (noproc && BASEPRI(ps))
cpstate = CP_IDLE;
#ifdef GPROF
s = pc - s_lowpc;
if (profiling < 2 && s < s_textsize)
kcount[s / (HISTFRACTION * sizeof (*kcount))]++;
#endif
}
/*
* We maintain statistics shown by user-level statistics
* programs: the amount of time in each cpu state, and
* the amount of time each of DK_NDRIVE ``drives'' is busy.
*/
cp_time[cpstate]++;
for (s = 0; s < DK_NDRIVE; s++)
if (dk_busy&(1<<s))
dk_time[s]++;
}
/*
* Software priority level clock interrupt.
* Run periodic events from timeout queue.
*/
/*ARGSUSED*/
#ifdef vax
softclock(pc, ps)
caddr_t pc;
int ps;
{
#endif
#ifdef sun
softclock()
{
int ps = u.u_ar0[PS];
caddr_t pc = (caddr_t)u.u_ar0[PC];
#endif
for (;;) {
register struct callout *p1;
register caddr_t arg;
register int (*func)();
register int a, s;
s = spl7();
if ((p1 = calltodo.c_next) == 0 || p1->c_time > 0) {
splx(s);
break;
}
arg = p1->c_arg; func = p1->c_func; a = p1->c_time;
calltodo.c_next = p1->c_next;
p1->c_next = callfree;
callfree = p1;
splx(s);
(*func)(arg, a);
}
/*
* If trapped user-mode, give it a profiling tick.
*/
if (USERMODE(ps) && u.u_prof.pr_scale) {
u.u_procp->p_flag |= SOWEUPC;
aston();
}
}
/*
* Arrange that (*fun)(arg) is called in tim/hz seconds.
*/
timeout(fun, arg, tim)
int (*fun)();
caddr_t arg;
int tim;
{
register struct callout *p1, *p2, *pnew;
register int t;
int s;
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)
if (p2->c_time > 0)
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_time > 0)
p2->c_next->c_time += p2->c_time;
p1->c_next = p2->c_next;
p2->c_next = callfree;
callfree = p2;
break;
}
}
splx(s);
}
/*
* Compute number of hz until specified time.
* Used to compute third argument to timeout() from an
* absolute time.
*/
hzto(tv)
struct timeval *tv;
{
register long ticks;
register long sec;
int s = spl7();
/*
* If number of milliseconds will fit in 32 bit arithmetic,
* then compute number of milliseconds to time and scale to
* ticks. Otherwise just compute number of hz in time, rounding
* times greater than representible to maximum value.
*
* Delta times less than 25 days can be computed ``exactly''.
* Maximum value for any timeout in 10ms ticks is 250 days.
*/
sec = tv->tv_sec - time.tv_sec;
if (sec <= 0x7fffffff / 1000 - 1000)
ticks = ((tv->tv_sec - time.tv_sec) * 1000 +
(tv->tv_usec - time.tv_usec) / 1000) / (tick / 1000);
else if (sec <= 0x7fffffff / hz)
ticks = sec * hz;
else
ticks = 0x7fffffff;
splx(s);
return (ticks);
}