/* $OpenBSD: kern_clock.c,v 1.64 2007/05/16 17:27:30 art Exp $ */
/* $NetBSD: kern_clock.c,v 1.34 1996/06/09 04:51:03 briggs Exp $ */
/*-
* Copyright (c) 1982, 1986, 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. 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 8.5 (Berkeley) 1/21/94
*/
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/dkstat.h>
#include <sys/timeout.h>
#include <sys/kernel.h>
#include <sys/limits.h>
#include <sys/proc.h>
#include <sys/user.h>
#include <sys/resourcevar.h>
#include <sys/signalvar.h>
#include <uvm/uvm_extern.h>
#include <sys/sysctl.h>
#include <sys/sched.h>
#ifdef __HAVE_TIMECOUNTER
#include <sys/timetc.h>
#endif
#include <machine/cpu.h>
#ifdef GPROF
#include <sys/gmon.h>
#endif
/*
* Clock handling routines.
*
* This code is written to operate with two timers that run independently of
* each other. The main clock, running hz times per second, is used to keep
* track of real time. The second timer handles kernel and user profiling,
* and does resource use estimation. If the second timer is programmable,
* it is randomized to avoid aliasing between the two clocks. For example,
* the randomization prevents an adversary from always giving up the cpu
* just before its quantum expires. Otherwise, it would never accumulate
* cpu ticks. The mean frequency of the second timer is stathz.
*
* If no second timer exists, stathz will be zero; in this case we drive
* profiling and statistics off the main clock. This WILL NOT be accurate;
* do not do it unless absolutely necessary.
*
* The statistics clock may (or may not) be run at a higher rate while
* profiling. This profile clock runs at profhz. We require that profhz
* be an integral multiple of stathz.
*
* If the statistics clock is running fast, it must be divided by the ratio
* profhz/stathz for statistics. (For profiling, every tick counts.)
*/
/*
* Bump a timeval by a small number of usec's.
*/
#define BUMPTIME(t, usec) { \
volatile struct timeval *tp = (t); \
long us; \
\
tp->tv_usec = us = tp->tv_usec + (usec); \
if (us >= 1000000) { \
tp->tv_usec = us - 1000000; \
tp->tv_sec++; \
} \
}
int stathz;
int schedhz;
int profhz;
int profprocs;
int ticks;
static int psdiv, pscnt; /* prof => stat divider */
int psratio; /* ratio: prof / stat */
long cp_time[CPUSTATES];
#ifndef __HAVE_TIMECOUNTER
int tickfix, tickfixinterval; /* used if tick not really integral */
static int tickfixcnt; /* accumulated fractional error */
volatile time_t time_second;
volatile time_t time_uptime;
volatile struct timeval time
__attribute__((__aligned__(__alignof__(quad_t))));
volatile struct timeval mono_time;
#endif
#ifdef __HAVE_GENERIC_SOFT_INTERRUPTS
void *softclock_si;
void generic_softclock(void *);
void
generic_softclock(void *ignore)
{
/*
* XXX - don't commit, just a dummy wrapper until we learn everyone
* deal with a changed proto for softclock().
*/
softclock();
}
#endif
/*
* Initialize clock frequencies and start both clocks running.
*/
void
initclocks(void)
{
int i;
#ifdef __HAVE_TIMECOUNTER
extern void inittimecounter(void);
#endif
#ifdef __HAVE_GENERIC_SOFT_INTERRUPTS
softclock_si = softintr_establish(IPL_SOFTCLOCK, generic_softclock, NULL);
if (softclock_si == NULL)
panic("initclocks: unable to register softclock intr");
#endif
/*
* Set divisors to 1 (normal case) and let the machine-specific
* code do its bit.
*/
psdiv = pscnt = 1;
cpu_initclocks();
/*
* Compute profhz/stathz, and fix profhz if needed.
*/
i = stathz ? stathz : hz;
if (profhz == 0)
profhz = i;
psratio = profhz / i;
#ifdef __HAVE_TIMECOUNTER
inittimecounter();
#endif
}
/*
* hardclock does the accounting needed for ITIMER_PROF and ITIMER_VIRTUAL.
* We don't want to send signals with psignal from hardclock because it makes
* MULTIPROCESSOR locking very complicated. Instead we use a small trick
* to send the signals safely and without blocking too many interrupts
* while doing that (signal handling can be heavy).
*
* hardclock detects that the itimer has expired, and schedules a timeout
* to deliver the signal. This works because of the following reasons:
* - The timeout structures can be in struct pstats because the timers
* can be only activated on curproc (never swapped). Swapout can
* only happen from a kernel thread and softclock runs before threads
* are scheduled.
* - The timeout can be scheduled with a 1 tick time because we're
* doing it before the timeout processing in hardclock. So it will
* be scheduled to run as soon as possible.
* - The timeout will be run in softclock which will run before we
* return to userland and process pending signals.
* - If the system is so busy that several VIRTUAL/PROF ticks are
* sent before softclock processing, we'll send only one signal.
* But if we'd send the signal from hardclock only one signal would
* be delivered to the user process. So userland will only see one
* signal anyway.
*/
void
virttimer_trampoline(void *v)
{
struct proc *p = v;
psignal(p, SIGVTALRM);
}
void
proftimer_trampoline(void *v)
{
struct proc *p = v;
psignal(p, SIGPROF);
}
/*
* The real-time timer, interrupting hz times per second.
*/
void
hardclock(struct clockframe *frame)
{
struct proc *p;
#ifndef __HAVE_TIMECOUNTER
int delta;
extern int tickdelta;
extern long timedelta;
extern int64_t ntp_tick_permanent;
extern int64_t ntp_tick_acc;
#endif
struct cpu_info *ci = curcpu();
p = curproc;
if (p && ((p->p_flag & (P_SYSTEM | P_WEXIT)) == 0)) {
struct pstats *pstats;
/*
* Run current process's virtual and profile time, as needed.
*/
pstats = p->p_stats;
if (CLKF_USERMODE(frame) &&
timerisset(&pstats->p_timer[ITIMER_VIRTUAL].it_value) &&
itimerdecr(&pstats->p_timer[ITIMER_VIRTUAL], tick) == 0)
timeout_add(&pstats->p_virt_to, 1);
if (timerisset(&pstats->p_timer[ITIMER_PROF].it_value) &&
itimerdecr(&pstats->p_timer[ITIMER_PROF], tick) == 0)
timeout_add(&pstats->p_prof_to, 1);
}
/*
* If no separate statistics clock is available, run it from here.
*/
if (stathz == 0)
statclock(frame);
if (--ci->ci_schedstate.spc_rrticks <= 0)
roundrobin(ci);
/*
* If we are not the primary CPU, we're not allowed to do
* any more work.
*/
if (CPU_IS_PRIMARY(ci) == 0)
return;
#ifndef __HAVE_TIMECOUNTER
/*
* Increment the time-of-day. The increment is normally just
* ``tick''. If the machine is one which has a clock frequency
* such that ``hz'' would not divide the second evenly into
* milliseconds, a periodic adjustment must be applied. Finally,
* if we are still adjusting the time (see adjtime()),
* ``tickdelta'' may also be added in.
*/
delta = tick;
if (tickfix) {
tickfixcnt += tickfix;
if (tickfixcnt >= tickfixinterval) {
delta++;
tickfixcnt -= tickfixinterval;
}
}
/* Imprecise 4bsd adjtime() handling */
if (timedelta != 0) {
delta += tickdelta;
timedelta -= tickdelta;
}
/*
* ntp_tick_permanent accumulates the clock correction each
* tick. The unit is ns per tick shifted left 32 bits. If we have
* accumulated more than 1us, we bump delta in the right
* direction. Use a loop to avoid long long div; typicallly
* the loops will be executed 0 or 1 iteration.
*/
if (ntp_tick_permanent != 0) {
ntp_tick_acc += ntp_tick_permanent;
while (ntp_tick_acc >= (1000LL << 32)) {
delta++;
ntp_tick_acc -= (1000LL << 32);
}
while (ntp_tick_acc <= -(1000LL << 32)) {
delta--;
ntp_tick_acc += (1000LL << 32);
}
}
BUMPTIME(&time, delta);
BUMPTIME(&mono_time, delta);
time_second = time.tv_sec;
time_uptime = mono_time.tv_sec;
#else
tc_ticktock();
#endif
/*
* Update real-time timeout queue.
* Process callouts at a very low cpu priority, so we don't keep the
* relatively high clock interrupt priority any longer than necessary.
*/
if (timeout_hardclock_update()) {
#ifdef __HAVE_GENERIC_SOFT_INTERRUPTS
softintr_schedule(softclock_si);
#else
setsoftclock();
#endif
}
}
/*
* Compute number of hz until specified time. Used to
* compute the second argument to timeout_add() from an absolute time.
*/
int
hzto(struct timeval *tv)
{
struct timeval now;
unsigned long ticks;
long sec, usec;
/*
* If the number of usecs in the whole seconds part of the time
* difference fits in a long, then the total number of usecs will
* fit in an unsigned long. Compute the total and convert it to
* ticks, rounding up and adding 1 to allow for the current tick
* to expire. Rounding also depends on unsigned long arithmetic
* to avoid overflow.
*
* Otherwise, if the number of ticks in the whole seconds part of
* the time difference fits in a long, then convert the parts to
* ticks separately and add, using similar rounding methods and
* overflow avoidance. This method would work in the previous
* case but it is slightly slower and assumes that hz is integral.
*
* Otherwise, round the time difference down to the maximum
* representable value.
*
* If ints have 32 bits, then the maximum value for any timeout in
* 10ms ticks is 248 days.
*/
getmicrotime(&now);
sec = tv->tv_sec - now.tv_sec;
usec = tv->tv_usec - now.tv_usec;
if (usec < 0) {
sec--;
usec += 1000000;
}
if (sec < 0 || (sec == 0 && usec <= 0)) {
ticks = 0;
} else if (sec <= LONG_MAX / 1000000)
ticks = (sec * 1000000 + (unsigned long)usec + (tick - 1))
/ tick + 1;
else if (sec <= LONG_MAX / hz)
ticks = sec * hz
+ ((unsigned long)usec + (tick - 1)) / tick + 1;
else
ticks = LONG_MAX;
if (ticks > INT_MAX)
ticks = INT_MAX;
return ((int)ticks);
}
/*
* Compute number of hz in the specified amount of time.
*/
int
tvtohz(struct timeval *tv)
{
unsigned long ticks;
long sec, usec;
/*
* If the number of usecs in the whole seconds part of the time
* fits in a long, then the total number of usecs will
* fit in an unsigned long. Compute the total and convert it to
* ticks, rounding up and adding 1 to allow for the current tick
* to expire. Rounding also depends on unsigned long arithmetic
* to avoid overflow.
*
* Otherwise, if the number of ticks in the whole seconds part of
* the time fits in a long, then convert the parts to
* ticks separately and add, using similar rounding methods and
* overflow avoidance. This method would work in the previous
* case but it is slightly slower and assumes that hz is integral.
*
* Otherwise, round the time down to the maximum
* representable value.
*
* If ints have 32 bits, then the maximum value for any timeout in
* 10ms ticks is 248 days.
*/
sec = tv->tv_sec;
usec = tv->tv_usec;
if (sec < 0 || (sec == 0 && usec <= 0))
ticks = 0;
else if (sec <= LONG_MAX / 1000000)
ticks = (sec * 1000000 + (unsigned long)usec + (tick - 1))
/ tick + 1;
else if (sec <= LONG_MAX / hz)
ticks = sec * hz
+ ((unsigned long)usec + (tick - 1)) / tick + 1;
else
ticks = LONG_MAX;
if (ticks > INT_MAX)
ticks = INT_MAX;
return ((int)ticks);
}
/*
* Start profiling on a process.
*
* Kernel profiling passes proc0 which never exits and hence
* keeps the profile clock running constantly.
*/
void
startprofclock(struct proc *p)
{
int s;
if ((p->p_flag & P_PROFIL) == 0) {
atomic_setbits_int(&p->p_flag, P_PROFIL);
if (++profprocs == 1 && stathz != 0) {
s = splstatclock();
psdiv = pscnt = psratio;
setstatclockrate(profhz);
splx(s);
}
}
}
/*
* Stop profiling on a process.
*/
void
stopprofclock(struct proc *p)
{
int s;
if (p->p_flag & P_PROFIL) {
atomic_clearbits_int(&p->p_flag, P_PROFIL);
if (--profprocs == 0 && stathz != 0) {
s = splstatclock();
psdiv = pscnt = 1;
setstatclockrate(stathz);
splx(s);
}
}
}
/*
* Statistics clock. Grab profile sample, and if divider reaches 0,
* do process and kernel statistics.
*/
void
statclock(struct clockframe *frame)
{
#ifdef GPROF
struct gmonparam *g;
int i;
#endif
struct cpu_info *ci = curcpu();
struct schedstate_percpu *spc = &ci->ci_schedstate;
struct proc *p = curproc;
/*
* Notice changes in divisor frequency, and adjust clock
* frequency accordingly.
*/
if (spc->spc_psdiv != psdiv) {
spc->spc_psdiv = psdiv;
spc->spc_pscnt = psdiv;
if (psdiv == 1) {
setstatclockrate(stathz);
} else {
setstatclockrate(profhz);
}
}
if (CLKF_USERMODE(frame)) {
if (p->p_flag & P_PROFIL)
addupc_intr(p, CLKF_PC(frame));
if (--spc->spc_pscnt > 0)
return;
/*
* Came from user mode; CPU was in user state.
* If this process is being profiled record the tick.
*/
p->p_uticks++;
if (p->p_nice > NZERO)
spc->spc_cp_time[CP_NICE]++;
else
spc->spc_cp_time[CP_USER]++;
} else {
#ifdef GPROF
/*
* Kernel statistics are just like addupc_intr, only easier.
*/
g = &_gmonparam;
if (g->state == GMON_PROF_ON) {
i = CLKF_PC(frame) - g->lowpc;
if (i < g->textsize) {
i /= HISTFRACTION * sizeof(*g->kcount);
g->kcount[i]++;
}
}
#endif
#if defined(PROC_PC)
if (p != NULL && p->p_flag & P_PROFIL)
addupc_intr(p, PROC_PC(p));
#endif
if (--spc->spc_pscnt > 0)
return;
/*
* Came from kernel mode, so we were:
* - handling an interrupt,
* - doing syscall or trap work on behalf of the current
* user process, or
* - spinning in the idle loop.
* Whichever it is, charge the time as appropriate.
* Note that we charge interrupts to the current process,
* regardless of whether they are ``for'' that process,
* so that we know how much of its real time was spent
* in ``non-process'' (i.e., interrupt) work.
*/
if (CLKF_INTR(frame)) {
if (p != NULL)
p->p_iticks++;
spc->spc_cp_time[CP_INTR]++;
} else if (p != NULL) {
p->p_sticks++;
spc->spc_cp_time[CP_SYS]++;
} else
spc->spc_cp_time[CP_IDLE]++;
}
spc->spc_pscnt = psdiv;
if (p != NULL) {
p->p_cpticks++;
/*
* If no schedclock is provided, call it here at ~~12-25 Hz;
* ~~16 Hz is best
*/
if (schedhz == 0) {
if ((++curcpu()->ci_schedstate.spc_schedticks & 3) ==
0)
schedclock(p);
}
}
}
/*
* Return information about system clocks.
*/
int
sysctl_clockrate(char *where, size_t *sizep)
{
struct clockinfo clkinfo;
/*
* Construct clockinfo structure.
*/
clkinfo.tick = tick;
clkinfo.tickadj = tickadj;
clkinfo.hz = hz;
clkinfo.profhz = profhz;
clkinfo.stathz = stathz ? stathz : hz;
return (sysctl_rdstruct(where, sizep, NULL, &clkinfo, sizeof(clkinfo)));
}
#ifndef __HAVE_TIMECOUNTER
/*
* Placeholders until everyone uses the timecounters code.
* Won't improve anything except maybe removing a bunch of bugs in fixed code.
*/
void
getmicrotime(struct timeval *tvp)
{
int s;
s = splhigh();
*tvp = time;
splx(s);
}
void
nanotime(struct timespec *tsp)
{
struct timeval tv;
microtime(&tv);
TIMEVAL_TO_TIMESPEC(&tv, tsp);
}
void
getnanotime(struct timespec *tsp)
{
struct timeval tv;
getmicrotime(&tv);
TIMEVAL_TO_TIMESPEC(&tv, tsp);
}
void
nanouptime(struct timespec *tsp)
{
struct timeval tv;
microuptime(&tv);
TIMEVAL_TO_TIMESPEC(&tv, tsp);
}
void
getnanouptime(struct timespec *tsp)
{
struct timeval tv;
getmicrouptime(&tv);
TIMEVAL_TO_TIMESPEC(&tv, tsp);
}
void
microuptime(struct timeval *tvp)
{
struct timeval tv;
microtime(&tv);
timersub(&tv, &boottime, tvp);
}
void
getmicrouptime(struct timeval *tvp)
{
int s;
s = splhigh();
*tvp = mono_time;
splx(s);
}
#endif /* __HAVE_TIMECOUNTER */
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