freebsd-skq/sys/kern/kern_timeout.c
Justin T. Gibbs ab36c06737 init_main.c subr_autoconf.c:
Add support for "interrupt driven configuration hooks".
	A component of the kernel can register a hook, most likely
	during auto-configuration, and receive a callback once
	interrupt services are available.  This callback will occur before
	the root and dump devices are configured, so the configuration
	task can affect the selection of those two devices or complete
	any tasks that need to be performed prior to launching init.
	System boot is posponed so long as a hook is registered.  The
	hook owner is responsible for removing the hook once their task
	is complete or the system boot can continue.

kern_acct.c kern_clock.c kern_exit.c kern_synch.c kern_time.c:
	Change the interface and implementation for the kernel callout
	service.  The new implemntaion is based on the work of
	Adam M. Costello and George Varghese, published in a technical
	report entitled "Redesigning the BSD Callout and Timer Facilities".
	The interface used in FreeBSD is a little different than the one
	outlined in the paper.  The new function prototypes are:

	struct callout_handle timeout(void (*func)(void *),
				      void *arg, int ticks);

	void untimeout(void (*func)(void *), void *arg,
		       struct callout_handle handle);

	If a client wishes to remove a timeout, it must store the
	callout_handle returned by timeout and pass it to untimeout.

	The new implementation gives 0(1) insert and removal of callouts
	making this interface scale well even for applications that
	keep 100s of callouts outstanding.

	See the updated timeout.9 man page for more details.
1997-09-21 22:00:25 +00:00

1338 lines
40 KiB
C

/*-
* 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. 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 8.5 (Berkeley) 1/21/94
* $Id: kern_clock.c,v 1.40 1997/09/07 05:25:43 bde Exp $
*/
/* Portions of this software are covered by the following: */
/******************************************************************************
* *
* Copyright (c) David L. Mills 1993, 1994 *
* *
* Permission to use, copy, modify, and distribute this software and its *
* documentation for any purpose and without fee is hereby granted, provided *
* that the above copyright notice appears in all copies and that both the *
* copyright notice and this permission notice appear in supporting *
* documentation, and that the name University of Delaware not be used in *
* advertising or publicity pertaining to distribution of the software *
* without specific, written prior permission. The University of Delaware *
* makes no representations about the suitability this software for any *
* purpose. It is provided "as is" without express or implied warranty. *
* *
*****************************************************************************/
#include "opt_cpu.h" /* XXX */
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/dkstat.h>
#include <sys/callout.h>
#include <sys/kernel.h>
#include <sys/proc.h>
#include <sys/resourcevar.h>
#include <sys/signalvar.h>
#include <sys/timex.h>
#include <vm/vm.h>
#include <sys/lock.h>
#include <vm/pmap.h>
#include <vm/vm_map.h>
#include <sys/sysctl.h>
#include <machine/cpu.h>
#define CLOCK_HAIR /* XXX */
#include <machine/clock.h>
#include <machine/limits.h>
#ifdef GPROF
#include <sys/gmon.h>
#endif
static void initclocks __P((void *dummy));
SYSINIT(clocks, SI_SUB_CLOCKS, SI_ORDER_FIRST, initclocks, NULL)
/* Exported to machdep.c. */
struct callout *callout;
struct callout_list callfree;
int callwheelsize, callwheelbits, callwheelmask;
struct callout_tailq *callwheel;
/* Some of these don't belong here, but it's easiest to concentrate them. */
static long cp_time[CPUSTATES];
long dk_seek[DK_NDRIVE];
static long dk_time[DK_NDRIVE]; /* time busy (in statclock ticks) */
long dk_wds[DK_NDRIVE];
long dk_wpms[DK_NDRIVE];
long dk_xfer[DK_NDRIVE];
int dk_busy;
int dk_ndrive = 0;
char dk_names[DK_NDRIVE][DK_NAMELEN];
long tk_cancc;
long tk_nin;
long tk_nout;
long tk_rawcc;
/*
* 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.)
*/
/*
* TODO:
* allocate more timeout table slots when table overflows.
*/
/*
* Bump a timeval by a small number of usec's.
*/
#define BUMPTIME(t, usec) { \
register volatile struct timeval *tp = (t); \
register long us; \
\
tp->tv_usec = us = tp->tv_usec + (usec); \
if (us >= 1000000) { \
tp->tv_usec = us - 1000000; \
tp->tv_sec++; \
} \
}
int stathz;
int profhz;
static int profprocs;
int ticks;
static int softticks; /* Like ticks, but for softclock(). */
static struct callout *nextsoftcheck; /* Next callout to be checked. */
static int psdiv, pscnt; /* prof => stat divider */
int psratio; /* ratio: prof / stat */
volatile struct timeval time;
volatile struct timeval mono_time;
/*
* Phase/frequency-lock loop (PLL/FLL) definitions
*
* The following variables are read and set by the ntp_adjtime() system
* call.
*
* time_state shows the state of the system clock, with values defined
* in the timex.h header file.
*
* time_status shows the status of the system clock, with bits defined
* in the timex.h header file.
*
* time_offset is used by the PLL/FLL to adjust the system time in small
* increments.
*
* time_constant determines the bandwidth or "stiffness" of the PLL.
*
* time_tolerance determines maximum frequency error or tolerance of the
* CPU clock oscillator and is a property of the architecture; however,
* in principle it could change as result of the presence of external
* discipline signals, for instance.
*
* time_precision is usually equal to the kernel tick variable; however,
* in cases where a precision clock counter or external clock is
* available, the resolution can be much less than this and depend on
* whether the external clock is working or not.
*
* time_maxerror is initialized by a ntp_adjtime() call and increased by
* the kernel once each second to reflect the maximum error
* bound growth.
*
* time_esterror is set and read by the ntp_adjtime() call, but
* otherwise not used by the kernel.
*/
int time_status = STA_UNSYNC; /* clock status bits */
int time_state = TIME_OK; /* clock state */
long time_offset = 0; /* time offset (us) */
long time_constant = 0; /* pll time constant */
long time_tolerance = MAXFREQ; /* frequency tolerance (scaled ppm) */
long time_precision = 1; /* clock precision (us) */
long time_maxerror = MAXPHASE; /* maximum error (us) */
long time_esterror = MAXPHASE; /* estimated error (us) */
/*
* The following variables establish the state of the PLL/FLL and the
* residual time and frequency offset of the local clock. The scale
* factors are defined in the timex.h header file.
*
* time_phase and time_freq are the phase increment and the frequency
* increment, respectively, of the kernel time variable at each tick of
* the clock.
*
* time_freq is set via ntp_adjtime() from a value stored in a file when
* the synchronization daemon is first started. Its value is retrieved
* via ntp_adjtime() and written to the file about once per hour by the
* daemon.
*
* time_adj is the adjustment added to the value of tick at each timer
* interrupt and is recomputed from time_phase and time_freq at each
* seconds rollover.
*
* time_reftime is the second's portion of the system time on the last
* call to ntp_adjtime(). It is used to adjust the time_freq variable
* and to increase the time_maxerror as the time since last update
* increases.
*/
static long time_phase = 0; /* phase offset (scaled us) */
long time_freq = 0; /* frequency offset (scaled ppm) */
static long time_adj = 0; /* tick adjust (scaled 1 / hz) */
static long time_reftime = 0; /* time at last adjustment (s) */
#ifdef PPS_SYNC
/*
* The following variables are used only if the kernel PPS discipline
* code is configured (PPS_SYNC). The scale factors are defined in the
* timex.h header file.
*
* pps_time contains the time at each calibration interval, as read by
* microtime(). pps_count counts the seconds of the calibration
* interval, the duration of which is nominally pps_shift in powers of
* two.
*
* pps_offset is the time offset produced by the time median filter
* pps_tf[], while pps_jitter is the dispersion (jitter) measured by
* this filter.
*
* pps_freq is the frequency offset produced by the frequency median
* filter pps_ff[], while pps_stabil is the dispersion (wander) measured
* by this filter.
*
* pps_usec is latched from a high resolution counter or external clock
* at pps_time. Here we want the hardware counter contents only, not the
* contents plus the time_tv.usec as usual.
*
* pps_valid counts the number of seconds since the last PPS update. It
* is used as a watchdog timer to disable the PPS discipline should the
* PPS signal be lost.
*
* pps_glitch counts the number of seconds since the beginning of an
* offset burst more than tick/2 from current nominal offset. It is used
* mainly to suppress error bursts due to priority conflicts between the
* PPS interrupt and timer interrupt.
*
* pps_intcnt counts the calibration intervals for use in the interval-
* adaptation algorithm. It's just too complicated for words.
*/
struct timeval pps_time; /* kernel time at last interval */
long pps_offset = 0; /* pps time offset (us) */
long pps_jitter = MAXTIME; /* pps time dispersion (jitter) (us) */
long pps_tf[] = {0, 0, 0}; /* pps time offset median filter (us) */
long pps_freq = 0; /* frequency offset (scaled ppm) */
long pps_stabil = MAXFREQ; /* frequency dispersion (scaled ppm) */
long pps_ff[] = {0, 0, 0}; /* frequency offset median filter */
long pps_usec = 0; /* microsec counter at last interval */
long pps_valid = PPS_VALID; /* pps signal watchdog counter */
int pps_glitch = 0; /* pps signal glitch counter */
int pps_count = 0; /* calibration interval counter (s) */
int pps_shift = PPS_SHIFT; /* interval duration (s) (shift) */
int pps_intcnt = 0; /* intervals at current duration */
/*
* PPS signal quality monitors
*
* pps_jitcnt counts the seconds that have been discarded because the
* jitter measured by the time median filter exceeds the limit MAXTIME
* (100 us).
*
* pps_calcnt counts the frequency calibration intervals, which are
* variable from 4 s to 256 s.
*
* pps_errcnt counts the calibration intervals which have been discarded
* because the wander exceeds the limit MAXFREQ (100 ppm) or where the
* calibration interval jitter exceeds two ticks.
*
* pps_stbcnt counts the calibration intervals that have been discarded
* because the frequency wander exceeds the limit MAXFREQ / 4 (25 us).
*/
long pps_jitcnt = 0; /* jitter limit exceeded */
long pps_calcnt = 0; /* calibration intervals */
long pps_errcnt = 0; /* calibration errors */
long pps_stbcnt = 0; /* stability limit exceeded */
#endif /* PPS_SYNC */
/* XXX none of this stuff works under FreeBSD */
#ifdef EXT_CLOCK
/*
* External clock definitions
*
* The following definitions and declarations are used only if an
* external clock (HIGHBALL or TPRO) is configured on the system.
*/
#define CLOCK_INTERVAL 30 /* CPU clock update interval (s) */
/*
* The clock_count variable is set to CLOCK_INTERVAL at each PPS
* interrupt and decremented once each second.
*/
int clock_count = 0; /* CPU clock counter */
#ifdef HIGHBALL
/*
* The clock_offset and clock_cpu variables are used by the HIGHBALL
* interface. The clock_offset variable defines the offset between
* system time and the HIGBALL counters. The clock_cpu variable contains
* the offset between the system clock and the HIGHBALL clock for use in
* disciplining the kernel time variable.
*/
extern struct timeval clock_offset; /* Highball clock offset */
long clock_cpu = 0; /* CPU clock adjust */
#endif /* HIGHBALL */
#endif /* EXT_CLOCK */
/*
* hardupdate() - local clock update
*
* This routine is called by ntp_adjtime() to update the local clock
* phase and frequency. The implementation is of an adaptive-parameter,
* hybrid phase/frequency-lock loop (PLL/FLL). The routine computes new
* time and frequency offset estimates for each call. If the kernel PPS
* discipline code is configured (PPS_SYNC), the PPS signal itself
* determines the new time offset, instead of the calling argument.
* Presumably, calls to ntp_adjtime() occur only when the caller
* believes the local clock is valid within some bound (+-128 ms with
* NTP). If the caller's time is far different than the PPS time, an
* argument will ensue, and it's not clear who will lose.
*
* For uncompensated quartz crystal oscillatores and nominal update
* intervals less than 1024 s, operation should be in phase-lock mode
* (STA_FLL = 0), where the loop is disciplined to phase. For update
* intervals greater than thiss, operation should be in frequency-lock
* mode (STA_FLL = 1), where the loop is disciplined to frequency.
*
* Note: splclock() is in effect.
*/
void
hardupdate(offset)
long offset;
{
long ltemp, mtemp;
if (!(time_status & STA_PLL) && !(time_status & STA_PPSTIME))
return;
ltemp = offset;
#ifdef PPS_SYNC
if (time_status & STA_PPSTIME && time_status & STA_PPSSIGNAL)
ltemp = pps_offset;
#endif /* PPS_SYNC */
/*
* Scale the phase adjustment and clamp to the operating range.
*/
if (ltemp > MAXPHASE)
time_offset = MAXPHASE << SHIFT_UPDATE;
else if (ltemp < -MAXPHASE)
time_offset = -(MAXPHASE << SHIFT_UPDATE);
else
time_offset = ltemp << SHIFT_UPDATE;
/*
* Select whether the frequency is to be controlled and in which
* mode (PLL or FLL). Clamp to the operating range. Ugly
* multiply/divide should be replaced someday.
*/
if (time_status & STA_FREQHOLD || time_reftime == 0)
time_reftime = time.tv_sec;
mtemp = time.tv_sec - time_reftime;
time_reftime = time.tv_sec;
if (time_status & STA_FLL) {
if (mtemp >= MINSEC) {
ltemp = ((time_offset / mtemp) << (SHIFT_USEC -
SHIFT_UPDATE));
if (ltemp < 0)
time_freq -= -ltemp >> SHIFT_KH;
else
time_freq += ltemp >> SHIFT_KH;
}
} else {
if (mtemp < MAXSEC) {
ltemp *= mtemp;
if (ltemp < 0)
time_freq -= -ltemp >> (time_constant +
time_constant + SHIFT_KF -
SHIFT_USEC);
else
time_freq += ltemp >> (time_constant +
time_constant + SHIFT_KF -
SHIFT_USEC);
}
}
if (time_freq > time_tolerance)
time_freq = time_tolerance;
else if (time_freq < -time_tolerance)
time_freq = -time_tolerance;
}
/*
* Initialize clock frequencies and start both clocks running.
*/
/* ARGSUSED*/
static void
initclocks(dummy)
void *dummy;
{
register int i;
/*
* 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;
}
/*
* The real-time timer, interrupting hz times per second.
*/
void
hardclock(frame)
register struct clockframe *frame;
{
register struct callout *p1;
register struct proc *p;
p = curproc;
if (p) {
register 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)
psignal(p, SIGVTALRM);
if (timerisset(&pstats->p_timer[ITIMER_PROF].it_value) &&
itimerdecr(&pstats->p_timer[ITIMER_PROF], tick) == 0)
psignal(p, SIGPROF);
}
/*
* If no separate statistics clock is available, run it from here.
*/
if (stathz == 0)
statclock(frame);
/*
* Increment the time-of-day.
*/
ticks++;
{
int time_update;
struct timeval newtime = time;
long ltemp;
if (timedelta == 0) {
time_update = CPU_THISTICKLEN(tick);
} else {
time_update = CPU_THISTICKLEN(tick) + tickdelta;
timedelta -= tickdelta;
}
BUMPTIME(&mono_time, time_update);
/*
* Compute the phase adjustment. If the low-order bits
* (time_phase) of the update overflow, bump the high-order bits
* (time_update).
*/
time_phase += time_adj;
if (time_phase <= -FINEUSEC) {
ltemp = -time_phase >> SHIFT_SCALE;
time_phase += ltemp << SHIFT_SCALE;
time_update -= ltemp;
}
else if (time_phase >= FINEUSEC) {
ltemp = time_phase >> SHIFT_SCALE;
time_phase -= ltemp << SHIFT_SCALE;
time_update += ltemp;
}
newtime.tv_usec += time_update;
/*
* On rollover of the second the phase adjustment to be used for
* the next second is calculated. Also, the maximum error is
* increased by the tolerance. If the PPS frequency discipline
* code is present, the phase is increased to compensate for the
* CPU clock oscillator frequency error.
*
* On a 32-bit machine and given parameters in the timex.h
* header file, the maximum phase adjustment is +-512 ms and
* maximum frequency offset is a tad less than) +-512 ppm. On a
* 64-bit machine, you shouldn't need to ask.
*/
if (newtime.tv_usec >= 1000000) {
newtime.tv_usec -= 1000000;
newtime.tv_sec++;
time_maxerror += time_tolerance >> SHIFT_USEC;
/*
* Compute the phase adjustment for the next second. In
* PLL mode, the offset is reduced by a fixed factor
* times the time constant. In FLL mode the offset is
* used directly. In either mode, the maximum phase
* adjustment for each second is clamped so as to spread
* the adjustment over not more than the number of
* seconds between updates.
*/
if (time_offset < 0) {
ltemp = -time_offset;
if (!(time_status & STA_FLL))
ltemp >>= SHIFT_KG + time_constant;
if (ltemp > (MAXPHASE / MINSEC) << SHIFT_UPDATE)
ltemp = (MAXPHASE / MINSEC) <<
SHIFT_UPDATE;
time_offset += ltemp;
time_adj = -ltemp << (SHIFT_SCALE - SHIFT_HZ -
SHIFT_UPDATE);
} else {
ltemp = time_offset;
if (!(time_status & STA_FLL))
ltemp >>= SHIFT_KG + time_constant;
if (ltemp > (MAXPHASE / MINSEC) << SHIFT_UPDATE)
ltemp = (MAXPHASE / MINSEC) <<
SHIFT_UPDATE;
time_offset -= ltemp;
time_adj = ltemp << (SHIFT_SCALE - SHIFT_HZ -
SHIFT_UPDATE);
}
/*
* Compute the frequency estimate and additional phase
* adjustment due to frequency error for the next
* second. When the PPS signal is engaged, gnaw on the
* watchdog counter and update the frequency computed by
* the pll and the PPS signal.
*/
#ifdef PPS_SYNC
pps_valid++;
if (pps_valid == PPS_VALID) {
pps_jitter = MAXTIME;
pps_stabil = MAXFREQ;
time_status &= ~(STA_PPSSIGNAL | STA_PPSJITTER |
STA_PPSWANDER | STA_PPSERROR);
}
ltemp = time_freq + pps_freq;
#else
ltemp = time_freq;
#endif /* PPS_SYNC */
if (ltemp < 0)
time_adj -= -ltemp >>
(SHIFT_USEC + SHIFT_HZ - SHIFT_SCALE);
else
time_adj += ltemp >>
(SHIFT_USEC + SHIFT_HZ - SHIFT_SCALE);
#if SHIFT_HZ == 7
/*
* When the CPU clock oscillator frequency is not a
* power of two in Hz, the SHIFT_HZ is only an
* approximate scale factor. In the SunOS kernel, this
* results in a PLL gain factor of 1/1.28 = 0.78 what it
* should be. In the following code the overall gain is
* increased by a factor of 1.25, which results in a
* residual error less than 3 percent.
*/
/* Same thing applies for FreeBSD --GAW */
if (hz == 100) {
if (time_adj < 0)
time_adj -= -time_adj >> 2;
else
time_adj += time_adj >> 2;
}
#endif /* SHIFT_HZ */
/* XXX - this is really bogus, but can't be fixed until
xntpd's idea of the system clock is fixed to know how
the user wants leap seconds handled; in the mean time,
we assume that users of NTP are running without proper
leap second support (this is now the default anyway) */
/*
* Leap second processing. If in leap-insert state at
* the end of the day, the system clock is set back one
* second; if in leap-delete state, the system clock is
* set ahead one second. The microtime() routine or
* external clock driver will insure that reported time
* is always monotonic. The ugly divides should be
* replaced.
*/
switch (time_state) {
case TIME_OK:
if (time_status & STA_INS)
time_state = TIME_INS;
else if (time_status & STA_DEL)
time_state = TIME_DEL;
break;
case TIME_INS:
if (newtime.tv_sec % 86400 == 0) {
newtime.tv_sec--;
time_state = TIME_OOP;
}
break;
case TIME_DEL:
if ((newtime.tv_sec + 1) % 86400 == 0) {
newtime.tv_sec++;
time_state = TIME_WAIT;
}
break;
case TIME_OOP:
time_state = TIME_WAIT;
break;
case TIME_WAIT:
if (!(time_status & (STA_INS | STA_DEL)))
time_state = TIME_OK;
}
}
CPU_CLOCKUPDATE(&time, &newtime);
}
/*
* Process callouts at a very low cpu priority, so we don't keep the
* relatively high clock interrupt priority any longer than necessary.
*/
if (TAILQ_FIRST(&callwheel[ticks & callwheelmask]) != NULL) {
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();
} else
setsoftclock();
} else if (softticks + 1 == ticks) {
++softticks;
}
}
/*
* The callout mechanism is based on the work of Adam M. Costello and
* George Varghese, published in a technical report entitled "Redesigning
* the BSD Callout and Timer Facilities" and modified slightly for inclusion
* in FreeBSD by Justin T. Gibbs. The original work on the data structures
* used in this implementation was published by G.Varghese and A. Lauck in
* the paper "Hashed and Hierarchical Timing Wheels: Data Structures for
* the Efficient Implementation of a Timer Facility" in the Proceedings of
* the 11th ACM Annual Symposium on Operating Systems Principles,
* Austin, Texas Nov 1987.
*/
/*
* Software (low priority) clock interrupt.
* Run periodic events from timeout queue.
*/
/*ARGSUSED*/
void
softclock()
{
register struct callout *c;
register int s;
register int steps; /*
* Number of steps taken since
* we last allowed interrupts.
*/
#ifndef MAX_SOFTCLOCK_STEPS
#define MAX_SOFTCLOCK_STEPS 100 /* Maximum allowed value of steps. */
#endif /* MAX_SOFTCLOCK_STEPS */
steps = 0;
s = splhigh();
while (softticks != ticks) {
c = TAILQ_FIRST(&callwheel[++softticks & callwheelmask]);
while (c) {
if (c->c_time > 0) {
c->c_time--;
c = TAILQ_NEXT(c, c_links.tqe);
++steps;
if (steps >= MAX_SOFTCLOCK_STEPS) {
nextsoftcheck = c;
splx(s);
/* Give hardclock() a chance. */
s = splhigh();
c = nextsoftcheck;
steps = 0;
}
} else {
void (*c_func)(void *);
void *c_arg;
nextsoftcheck = TAILQ_NEXT(c, c_links.tqe);
TAILQ_REMOVE(c->c_bucket, c, c_links.tqe);
c_func = c->c_func;
c_arg = c->c_arg;
c->c_func = NULL;
SLIST_INSERT_HEAD(&callfree, c, c_links.sle);
splx(s);
c_func(c_arg);
s = splhigh();
steps = 0;
c = nextsoftcheck;
}
}
}
nextsoftcheck = NULL;
splx(s);
}
/*
* timeout --
* Execute a function after a specified length of time.
*
* untimeout --
* Cancel previous timeout function call.
*
* callout_handle_init --
* Initialize a handle so that using it with untimeout is benign.
*
* See AT&T BCI Driver Reference Manual for specification. This
* implementation differs from that one in that although an
* identification value is returned from timeout, the original
* arguments to timeout as well as the identifier are used to
* identify entries for untimeout.
*/
struct callout_handle
timeout(ftn, arg, to_ticks)
timeout_t ftn;
void *arg;
register int to_ticks;
{
int s;
struct callout *new;
struct callout_handle handle;
if (to_ticks <= 0)
to_ticks = 1;
/* Lock out the clock. */
s = splhigh();
/* Fill in the next free callout structure. */
new = SLIST_FIRST(&callfree);
if (new == NULL)
/* XXX Attempt to malloc first */
panic("timeout table full");
SLIST_REMOVE_HEAD(&callfree, c_links.sle);
new->c_arg = arg;
new->c_func = ftn;
new->c_time = to_ticks >> callwheelbits;
new->c_bucket = &callwheel[(ticks + to_ticks) & callwheelmask];
TAILQ_INSERT_TAIL(new->c_bucket, new, c_links.tqe);
splx(s);
handle.callout = new;
return (handle);
}
void
untimeout(ftn, arg, handle)
timeout_t ftn;
void *arg;
struct callout_handle handle;
{
register struct callout *p, *t;
register int s;
/*
* Check for a handle that was initialized
* by callout_handle_init, but never used
* for a real timeout.
*/
if (handle.callout == NULL)
return;
s = splhigh();
if ((handle.callout->c_func == ftn)
&& (handle.callout->c_arg == arg)) {
if (nextsoftcheck == handle.callout) {
nextsoftcheck = TAILQ_NEXT(handle.callout, c_links.tqe);
}
TAILQ_REMOVE(handle.callout->c_bucket,
handle.callout, c_links.tqe);
handle.callout->c_func = NULL;
SLIST_INSERT_HEAD(&callfree, handle.callout, c_links.sle);
}
splx(s);
}
void
callout_handle_init(struct callout_handle *handle)
{
handle->callout = NULL;
}
void
gettime(struct timeval *tvp)
{
int s;
s = splclock();
/* XXX should use microtime() iff tv_usec is used. */
*tvp = time;
splx(s);
}
/*
* Compute number of hz until specified time. Used to
* compute third argument to timeout() from an absolute time.
*/
int
hzto(tv)
struct timeval *tv;
{
register unsigned long ticks;
register long sec, usec;
int s;
/*
* 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.
*/
s = splclock();
sec = tv->tv_sec - time.tv_sec;
usec = tv->tv_usec - time.tv_usec;
splx(s);
if (usec < 0) {
sec--;
usec += 1000000;
}
if (sec < 0) {
#ifdef DIAGNOSTIC
printf("hzto: negative time difference %ld sec %ld usec\n",
sec, usec);
#endif
ticks = 1;
} 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 (ticks);
}
/*
* Start profiling on a process.
*
* Kernel profiling passes proc0 which never exits and hence
* keeps the profile clock running constantly.
*/
void
startprofclock(p)
register struct proc *p;
{
int s;
if ((p->p_flag & P_PROFIL) == 0) {
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(p)
register struct proc *p;
{
int s;
if (p->p_flag & P_PROFIL) {
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(frame)
register struct clockframe *frame;
{
#ifdef GPROF
register struct gmonparam *g;
#endif
register struct proc *p;
register int i;
struct pstats *pstats;
long rss;
struct rusage *ru;
struct vmspace *vm;
if (CLKF_USERMODE(frame)) {
p = curproc;
if (p->p_flag & P_PROFIL)
addupc_intr(p, CLKF_PC(frame), 1);
if (--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)
cp_time[CP_NICE]++;
else
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 (--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.
*/
p = curproc;
if (CLKF_INTR(frame)) {
if (p != NULL)
p->p_iticks++;
cp_time[CP_INTR]++;
} else if (p != NULL && !(p->p_flag & P_IDLEPROC)) {
p->p_sticks++;
cp_time[CP_SYS]++;
} else
cp_time[CP_IDLE]++;
}
pscnt = psdiv;
/*
* 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.
*
* XXX should either run linked list of drives, or (better)
* grab timestamps in the start & done code.
*/
for (i = 0; i < DK_NDRIVE; i++)
if (dk_busy & (1 << i))
dk_time[i]++;
/*
* 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. The formula for computing
* priorities (in kern_synch.c) will compute a different value each
* time p_estcpu 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 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.
*/
if (p != NULL) {
p->p_cpticks++;
if (++p->p_estcpu == 0)
p->p_estcpu--;
if ((p->p_estcpu & 3) == 0) {
resetpriority(p);
if (p->p_priority >= PUSER)
p->p_priority = p->p_usrpri;
}
/* Update resource usage integrals and maximums. */
if ((pstats = p->p_stats) != NULL &&
(ru = &pstats->p_ru) != NULL &&
(vm = p->p_vmspace) != NULL) {
ru->ru_ixrss += vm->vm_tsize * PAGE_SIZE / 1024;
ru->ru_idrss += vm->vm_dsize * PAGE_SIZE / 1024;
ru->ru_isrss += vm->vm_ssize * PAGE_SIZE / 1024;
rss = vm->vm_pmap.pm_stats.resident_count *
PAGE_SIZE / 1024;
if (ru->ru_maxrss < rss)
ru->ru_maxrss = rss;
}
}
}
/*
* Return information about system clocks.
*/
static int
sysctl_kern_clockrate SYSCTL_HANDLER_ARGS
{
struct clockinfo clkinfo;
/*
* Construct clockinfo structure.
*/
clkinfo.hz = hz;
clkinfo.tick = tick;
clkinfo.tickadj = tickadj;
clkinfo.profhz = profhz;
clkinfo.stathz = stathz ? stathz : hz;
return (sysctl_handle_opaque(oidp, &clkinfo, sizeof clkinfo, req));
}
SYSCTL_PROC(_kern, KERN_CLOCKRATE, clockrate, CTLTYPE_STRUCT|CTLFLAG_RD,
0, 0, sysctl_kern_clockrate, "S,clockinfo","");
#ifdef PPS_SYNC
/*
* hardpps() - discipline CPU clock oscillator to external PPS signal
*
* This routine is called at each PPS interrupt in order to discipline
* the CPU clock oscillator to the PPS signal. It measures the PPS phase
* and leaves it in a handy spot for the hardclock() routine. It
* integrates successive PPS phase differences and calculates the
* frequency offset. This is used in hardclock() to discipline the CPU
* clock oscillator so that intrinsic frequency error is cancelled out.
* The code requires the caller to capture the time and hardware counter
* value at the on-time PPS signal transition.
*
* Note that, on some Unix systems, this routine runs at an interrupt
* priority level higher than the timer interrupt routine hardclock().
* Therefore, the variables used are distinct from the hardclock()
* variables, except for certain exceptions: The PPS frequency pps_freq
* and phase pps_offset variables are determined by this routine and
* updated atomically. The time_tolerance variable can be considered a
* constant, since it is infrequently changed, and then only when the
* PPS signal is disabled. The watchdog counter pps_valid is updated
* once per second by hardclock() and is atomically cleared in this
* routine.
*/
void
hardpps(tvp, usec)
struct timeval *tvp; /* time at PPS */
long usec; /* hardware counter at PPS */
{
long u_usec, v_usec, bigtick;
long cal_sec, cal_usec;
/*
* An occasional glitch can be produced when the PPS interrupt
* occurs in the hardclock() routine before the time variable is
* updated. Here the offset is discarded when the difference
* between it and the last one is greater than tick/2, but not
* if the interval since the first discard exceeds 30 s.
*/
time_status |= STA_PPSSIGNAL;
time_status &= ~(STA_PPSJITTER | STA_PPSWANDER | STA_PPSERROR);
pps_valid = 0;
u_usec = -tvp->tv_usec;
if (u_usec < -500000)
u_usec += 1000000;
v_usec = pps_offset - u_usec;
if (v_usec < 0)
v_usec = -v_usec;
if (v_usec > (tick >> 1)) {
if (pps_glitch > MAXGLITCH) {
pps_glitch = 0;
pps_tf[2] = u_usec;
pps_tf[1] = u_usec;
} else {
pps_glitch++;
u_usec = pps_offset;
}
} else
pps_glitch = 0;
/*
* A three-stage median filter is used to help deglitch the pps
* time. The median sample becomes the time offset estimate; the
* difference between the other two samples becomes the time
* dispersion (jitter) estimate.
*/
pps_tf[2] = pps_tf[1];
pps_tf[1] = pps_tf[0];
pps_tf[0] = u_usec;
if (pps_tf[0] > pps_tf[1]) {
if (pps_tf[1] > pps_tf[2]) {
pps_offset = pps_tf[1]; /* 0 1 2 */
v_usec = pps_tf[0] - pps_tf[2];
} else if (pps_tf[2] > pps_tf[0]) {
pps_offset = pps_tf[0]; /* 2 0 1 */
v_usec = pps_tf[2] - pps_tf[1];
} else {
pps_offset = pps_tf[2]; /* 0 2 1 */
v_usec = pps_tf[0] - pps_tf[1];
}
} else {
if (pps_tf[1] < pps_tf[2]) {
pps_offset = pps_tf[1]; /* 2 1 0 */
v_usec = pps_tf[2] - pps_tf[0];
} else if (pps_tf[2] < pps_tf[0]) {
pps_offset = pps_tf[0]; /* 1 0 2 */
v_usec = pps_tf[1] - pps_tf[2];
} else {
pps_offset = pps_tf[2]; /* 1 2 0 */
v_usec = pps_tf[1] - pps_tf[0];
}
}
if (v_usec > MAXTIME)
pps_jitcnt++;
v_usec = (v_usec << PPS_AVG) - pps_jitter;
if (v_usec < 0)
pps_jitter -= -v_usec >> PPS_AVG;
else
pps_jitter += v_usec >> PPS_AVG;
if (pps_jitter > (MAXTIME >> 1))
time_status |= STA_PPSJITTER;
/*
* During the calibration interval adjust the starting time when
* the tick overflows. At the end of the interval compute the
* duration of the interval and the difference of the hardware
* counters at the beginning and end of the interval. This code
* is deliciously complicated by the fact valid differences may
* exceed the value of tick when using long calibration
* intervals and small ticks. Note that the counter can be
* greater than tick if caught at just the wrong instant, but
* the values returned and used here are correct.
*/
bigtick = (long)tick << SHIFT_USEC;
pps_usec -= pps_freq;
if (pps_usec >= bigtick)
pps_usec -= bigtick;
if (pps_usec < 0)
pps_usec += bigtick;
pps_time.tv_sec++;
pps_count++;
if (pps_count < (1 << pps_shift))
return;
pps_count = 0;
pps_calcnt++;
u_usec = usec << SHIFT_USEC;
v_usec = pps_usec - u_usec;
if (v_usec >= bigtick >> 1)
v_usec -= bigtick;
if (v_usec < -(bigtick >> 1))
v_usec += bigtick;
if (v_usec < 0)
v_usec = -(-v_usec >> pps_shift);
else
v_usec = v_usec >> pps_shift;
pps_usec = u_usec;
cal_sec = tvp->tv_sec;
cal_usec = tvp->tv_usec;
cal_sec -= pps_time.tv_sec;
cal_usec -= pps_time.tv_usec;
if (cal_usec < 0) {
cal_usec += 1000000;
cal_sec--;
}
pps_time = *tvp;
/*
* Check for lost interrupts, noise, excessive jitter and
* excessive frequency error. The number of timer ticks during
* the interval may vary +-1 tick. Add to this a margin of one
* tick for the PPS signal jitter and maximum frequency
* deviation. If the limits are exceeded, the calibration
* interval is reset to the minimum and we start over.
*/
u_usec = (long)tick << 1;
if (!((cal_sec == -1 && cal_usec > (1000000 - u_usec))
|| (cal_sec == 0 && cal_usec < u_usec))
|| v_usec > time_tolerance || v_usec < -time_tolerance) {
pps_errcnt++;
pps_shift = PPS_SHIFT;
pps_intcnt = 0;
time_status |= STA_PPSERROR;
return;
}
/*
* A three-stage median filter is used to help deglitch the pps
* frequency. The median sample becomes the frequency offset
* estimate; the difference between the other two samples
* becomes the frequency dispersion (stability) estimate.
*/
pps_ff[2] = pps_ff[1];
pps_ff[1] = pps_ff[0];
pps_ff[0] = v_usec;
if (pps_ff[0] > pps_ff[1]) {
if (pps_ff[1] > pps_ff[2]) {
u_usec = pps_ff[1]; /* 0 1 2 */
v_usec = pps_ff[0] - pps_ff[2];
} else if (pps_ff[2] > pps_ff[0]) {
u_usec = pps_ff[0]; /* 2 0 1 */
v_usec = pps_ff[2] - pps_ff[1];
} else {
u_usec = pps_ff[2]; /* 0 2 1 */
v_usec = pps_ff[0] - pps_ff[1];
}
} else {
if (pps_ff[1] < pps_ff[2]) {
u_usec = pps_ff[1]; /* 2 1 0 */
v_usec = pps_ff[2] - pps_ff[0];
} else if (pps_ff[2] < pps_ff[0]) {
u_usec = pps_ff[0]; /* 1 0 2 */
v_usec = pps_ff[1] - pps_ff[2];
} else {
u_usec = pps_ff[2]; /* 1 2 0 */
v_usec = pps_ff[1] - pps_ff[0];
}
}
/*
* Here the frequency dispersion (stability) is updated. If it
* is less than one-fourth the maximum (MAXFREQ), the frequency
* offset is updated as well, but clamped to the tolerance. It
* will be processed later by the hardclock() routine.
*/
v_usec = (v_usec >> 1) - pps_stabil;
if (v_usec < 0)
pps_stabil -= -v_usec >> PPS_AVG;
else
pps_stabil += v_usec >> PPS_AVG;
if (pps_stabil > MAXFREQ >> 2) {
pps_stbcnt++;
time_status |= STA_PPSWANDER;
return;
}
if (time_status & STA_PPSFREQ) {
if (u_usec < 0) {
pps_freq -= -u_usec >> PPS_AVG;
if (pps_freq < -time_tolerance)
pps_freq = -time_tolerance;
u_usec = -u_usec;
} else {
pps_freq += u_usec >> PPS_AVG;
if (pps_freq > time_tolerance)
pps_freq = time_tolerance;
}
}
/*
* Here the calibration interval is adjusted. If the maximum
* time difference is greater than tick / 4, reduce the interval
* by half. If this is not the case for four consecutive
* intervals, double the interval.
*/
if (u_usec << pps_shift > bigtick >> 2) {
pps_intcnt = 0;
if (pps_shift > PPS_SHIFT)
pps_shift--;
} else if (pps_intcnt >= 4) {
pps_intcnt = 0;
if (pps_shift < PPS_SHIFTMAX)
pps_shift++;
} else
pps_intcnt++;
}
#endif /* PPS_SYNC */