Net2/usr/src/sys/kern/kern_clock.c
/*-
* Copyright (c) 1982, 1986, 1991 The Regents of the University of California.
* All rights reserved.
*
* 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_clock.c 7.16 (Berkeley) 5/9/91
*/
#include "param.h"
#include "systm.h"
#include "dkstat.h"
#include "callout.h"
#include "kernel.h"
#include "proc.h"
#include "resourcevar.h"
#include "machine/cpu.h"
#ifdef GPROF
#include "gprof.h"
#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:
* time of day, system/user timing, timeouts, profiling on separate timers
* allocate more timeout table slots when table overflows.
*/
/*
* Bump a timeval by a small number of usec's.
*/
#define BUMPTIME(t, usec) { \
register struct timeval *tp = (t); \
\
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.
*/
hardclock(frame)
clockframe frame;
{
register struct callout *p1;
register struct proc *p = curproc;
register struct pstats *pstats;
register int s;
int needsoft = 0;
extern int tickdelta;
extern long timedelta;
/*
* 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.
*/
p1 = calltodo.c_next;
while (p1) {
if (--p1->c_time > 0)
break;
needsoft = 1;
if (p1->c_time == 0)
break;
p1 = p1->c_next;
}
/*
* Curproc (now in p) is null if no process is running.
* We assume that curproc is set in user mode!
*/
if (p)
pstats = p->p_stats;
/*
* 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 (CLKF_USERMODE(&frame)) {
if (pstats->p_prof.pr_scale)
needsoft = 1;
/*
* CPU was in user state. Increment
* user time counter, and process process-virtual time
* interval timer.
*/
BUMPTIME(&p->p_utime, tick);
if (timerisset(&pstats->p_timer[ITIMER_VIRTUAL].it_value) &&
itimerdecr(&pstats->p_timer[ITIMER_VIRTUAL], tick) == 0)
psignal(p, SIGVTALRM);
} else {
/*
* CPU was in system state.
*/
if (p)
BUMPTIME(&p->p_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 (p) {
if ((p->p_utime.tv_sec+p->p_stime.tv_sec+1) >
p->p_rlimit[RLIMIT_CPU].rlim_cur) {
psignal(p, SIGXCPU);
if (p->p_rlimit[RLIMIT_CPU].rlim_cur <
p->p_rlimit[RLIMIT_CPU].rlim_max)
p->p_rlimit[RLIMIT_CPU].rlim_cur += 5;
}
if (timerisset(&pstats->p_timer[ITIMER_PROF].it_value) &&
itimerdecr(&pstats->p_timer[ITIMER_PROF], tick) == 0)
psignal(p, SIGPROF);
/*
* 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.
*/
p->p_cpticks++;
if (++p->p_cpu == 0)
p->p_cpu--;
if ((p->p_cpu&3) == 0) {
setpri(p);
if (p->p_pri >= PUSER)
p->p_pri = p->p_usrpri;
}
}
/*
* If the alternate clock has not made itself known then
* we must gather the statistics.
*/
if (phz == 0)
gatherstats(&frame);
/*
* 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.
*/
if (timedelta == 0)
BUMPTIME(&time, tick)
else {
register delta;
if (timedelta < 0) {
delta = tick - tickdelta;
timedelta += tickdelta;
} else {
delta = tick + tickdelta;
timedelta -= tickdelta;
}
BUMPTIME(&time, delta);
}
if (needsoft) {
if (CLKF_BASEPRI(&frame)) {
/*
* Save the overhead of a software interrupt;
* it will happen as soon as we return, so do it now.
*/
(void) splsoftclock();
softclock(frame);
} else
setsoftclock();
}
}
int dk_ndrive = DK_NDRIVE;
/*
* 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(framep)
clockframe *framep;
{
register int cpstate, s;
/*
* Determine what state the cpu is in.
*/
if (CLKF_USERMODE(framep)) {
/*
* CPU was in user state.
*/
if (curproc->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 (curproc == NULL && CLKF_BASEPRI(framep))
cpstate = CP_IDLE;
#ifdef GPROF
s = CLKF_PC(framep) - 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*/
softclock(frame)
clockframe frame;
{
for (;;) {
register struct callout *p1;
register caddr_t arg;
register int (*func)();
register int a, s;
s = splhigh();
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 and profiling, give it
* a profiling tick.
*/
if (CLKF_USERMODE(&frame)) {
register struct proc *p = curproc;
if (p->p_stats->p_prof.pr_scale)
profile_tick(p, &frame);
/*
* Check to see if process has accumulated
* more than 10 minutes of user time. If so
* reduce priority to give others a chance.
*/
if (p->p_ucred->cr_uid && p->p_nice == NZERO &&
p->p_utime.tv_sec > 10 * 60) {
p->p_nice = NZERO + 4;
setpri(p);
p->p_pri = p->p_usrpri;
}
}
}
/*
* Arrange that (*func)(arg) is called in t/hz seconds.
*/
timeout(func, arg, t)
int (*func)();
caddr_t arg;
register int t;
{
register struct callout *p1, *p2, *pnew;
register int s = splhigh();
if (t <= 0)
t = 1;
pnew = callfree;
if (pnew == NULL)
panic("timeout table overflow");
callfree = pnew->c_next;
pnew->c_arg = arg;
pnew->c_func = func;
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(func, arg)
int (*func)();
caddr_t arg;
{
register struct callout *p1, *p2;
register int s;
s = splhigh();
for (p1 = &calltodo; (p2 = p1->c_next) != 0; p1 = p2) {
if (p2->c_func == func && 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 = splhigh();
/*
* 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);
}