NetBSD/sys/kern/kern_clock.c

1814 lines
51 KiB
C
Raw Normal View History

/* $NetBSD: kern_clock.c,v 1.80 2002/08/07 05:16:22 briggs Exp $ */
/*-
* Copyright (c) 2000 The NetBSD Foundation, Inc.
* All rights reserved.
*
* This code is derived from software contributed to The NetBSD Foundation
* by Jason R. Thorpe of the Numerical Aerospace Simulation Facility,
* NASA Ames Research Center.
*
* 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 NetBSD
* Foundation, Inc. and its contributors.
* 4. Neither the name of The NetBSD Foundation 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 NETBSD FOUNDATION, INC. 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 FOUNDATION 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.
*/
/*-
* 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
*/
2001-11-12 18:25:01 +03:00
#include <sys/cdefs.h>
__KERNEL_RCSID(0, "$NetBSD: kern_clock.c,v 1.80 2002/08/07 05:16:22 briggs Exp $");
2001-11-12 18:25:01 +03:00
2001-09-13 09:22:16 +04:00
#include "opt_callout.h"
#include "opt_ntp.h"
#include "opt_perfctrs.h"
#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>
1996-02-04 05:15:01 +03:00
#include <sys/signalvar.h>
1996-02-09 21:59:18 +03:00
#include <sys/sysctl.h>
#include <sys/timex.h>
Scheduler bug fixes and reorganization * fix the ancient nice(1) bug, where nice +20 processes incorrectly steal 10 - 20% of the CPU, (or even more depending on load average) * provide a new schedclk() mechanism at a new clock at schedhz, so high platform hz values don't cause nice +0 processes to look like they are niced * change the algorithm slightly, and reorganize the code a lot * fix percent-CPU calculation bugs, and eliminate some no-op code === nice bug === Correctly divide the scheduler queues between niced and compute-bound processes. The current nice weight of two (sort of, see `algorithm change' below) neatly divides the USRPRI queues in half; this should have been used to clip p_estcpu, instead of UCHAR_MAX. Besides being the wrong amount, clipping an unsigned char to UCHAR_MAX is a no-op, and it was done after decay_cpu() which can only _reduce_ the value. It has to be kept <= NICE_WEIGHT * PRIO_MAX - PPQ or processes can scheduler-penalize themselves onto the same queue as nice +20 processes. (Or even a higher one.) === New schedclk() mechansism === Some platforms should be cutting down stathz before hitting the scheduler, since the scheduler algorithm only works right in the vicinity of 64 Hz. Rather than prescale hz, then scale back and forth by 4 every time p_estcpu is touched (each occurance an abstraction violation), use p_estcpu without scaling and require schedhz to be generated directly at the right frequency. Use a default stathz (well, actually, profhz) / 4, so nothing changes unless a platform defines schedhz and a new clock. Define these for alpha, where hz==1024, and nice was totally broke. === Algorithm change === The nice value used to be added to the exponentially-decayed scheduler history value p_estcpu, in _addition_ to be incorporated directly (with greater wieght) into the priority calculation. At first glance, it appears to be a pointless increase of 1/8 the nice effect (pri = p_estcpu/4 + nice*2), but it's actually at least 3x that because it will ramp up linearly but be decayed only exponentially, thus converging to an additional .75 nice for a loadaverage of one. I killed this, it makes the behavior hard to control, almost impossible to analyze, and the effect (~~nothing at for the first second, then somewhat increased niceness after three seconds or more, depending on load average) pointless. === Other bugs === hz -> profhz in the p_pctcpu = f(p_cpticks) calcuation. Collect scheduler functionality. Try to put each abstraction in just one place.
1999-02-23 05:56:03 +03:00
#include <sys/sched.h>
#ifdef CALLWHEEL_STATS
#include <sys/device.h>
#endif
#include <machine/cpu.h>
#ifdef __HAVE_GENERIC_SOFT_INTERRUPTS
#include <machine/intr.h>
#endif
#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.)
*/
#ifdef NTP /* NTP phase-locked loop in kernel */
/*
* 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_state = TIME_OK; /* clock state */
int time_status = STA_UNSYNC; /* clock status bits */
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.
*
* 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 at 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.
*/
long time_phase = 0; /* phase offset (scaled us) */
long time_freq = 0; /* frequency offset (scaled ppm) */
long time_adj = 0; /* tick adjust (scaled 1 / hz) */
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_tf[] = {0, 0, 0}; /* pps time offset median filter (us) */
long pps_offset = 0; /* pps time offset (us) */
long pps_jitter = MAXTIME; /* time dispersion (jitter) (us) */
long pps_ff[] = {0, 0, 0}; /* pps frequency offset median filter */
long pps_freq = 0; /* frequency offset (scaled ppm) */
long pps_stabil = MAXFREQ; /* frequency dispersion (scaled ppm) */
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 */
#ifdef EXT_CLOCK
/*
* External clock definitions
*
* The following definitions and declarations are used only if an
* external clock 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 */
#endif /* NTP */
/*
* Bump a timeval by a small number of usec's.
*/
#define BUMPTIME(t, usec) { \
2000-03-30 13:27:11 +04:00
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 profhz;
int profsrc;
2001-05-06 17:46:34 +04:00
int schedhz;
int profprocs;
int softclock_running; /* 1 => softclock() is running */
static int psdiv; /* prof => stat divider */
int psratio; /* ratio: prof / stat */
int tickfix, tickfixinterval; /* used if tick not really integral */
1996-06-09 08:51:03 +04:00
#ifndef NTP
static int tickfixcnt; /* accumulated fractional error */
1996-06-09 08:51:03 +04:00
#else
int fixtick; /* used by NTP for same */
int shifthz;
#endif
/*
* We might want ldd to load the both words from time at once.
* To succeed we need to be quadword aligned.
* The sparc already does that, and that it has worked so far is a fluke.
*/
volatile struct timeval time __attribute__((__aligned__(__alignof__(quad_t))));
volatile struct timeval mono_time;
/*
* 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 Justin Gibbs's subsequent
* integration into FreeBSD, modified for NetBSD by Jason R. Thorpe.
*
* 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 System Principles, Austin, Texas,
* November 1987.
*/
struct callout_queue *callwheel;
int callwheelsize, callwheelbits, callwheelmask;
static struct callout *nextsoftcheck; /* next callout to be checked */
#ifdef CALLWHEEL_STATS
int *callwheel_sizes; /* per-bucket length count */
struct evcnt callwheel_collisions; /* number of hash collisions */
struct evcnt callwheel_maxlength; /* length of the longest hash chain */
struct evcnt callwheel_count; /* # callouts currently */
struct evcnt callwheel_established; /* # callouts established */
struct evcnt callwheel_fired; /* # callouts that fired */
struct evcnt callwheel_disestablished; /* # callouts disestablished */
struct evcnt callwheel_changed; /* # callouts changed */
struct evcnt callwheel_softclocks; /* # times softclock() called */
struct evcnt callwheel_softchecks; /* # checks per softclock() */
struct evcnt callwheel_softempty; /* # empty buckets seen */
struct evcnt callwheel_hintworked; /* # times hint saved scan */
#endif /* CALLWHEEL_STATS */
/*
* This value indicates the number of consecutive callouts that
* will be checked before we allow interrupts to have a chance
* again.
*/
#ifndef MAX_SOFTCLOCK_STEPS
#define MAX_SOFTCLOCK_STEPS 100
#endif
struct simplelock callwheel_slock;
#define CALLWHEEL_LOCK(s) \
do { \
s = splclock(); \
simple_lock(&callwheel_slock); \
} while (0)
#define CALLWHEEL_UNLOCK(s) \
do { \
simple_unlock(&callwheel_slock); \
splx(s); \
} while (0)
static void callout_stop_locked(struct callout *);
/*
* These are both protected by callwheel_lock.
* XXX SHOULD BE STATIC!!
*/
u_int64_t hardclock_ticks, softclock_ticks;
#ifdef __HAVE_GENERIC_SOFT_INTERRUPTS
void softclock(void *);
void *softclock_si;
#endif
/*
* Initialize clock frequencies and start both clocks running.
*/
void
2000-08-01 08:57:28 +04:00
initclocks(void)
{
2000-03-30 13:27:11 +04:00
int i;
#ifdef __HAVE_GENERIC_SOFT_INTERRUPTS
softclock_si = softintr_establish(IPL_SOFTCLOCK, 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 = 1;
cpu_initclocks();
/*
* Compute profhz/stathz/rrticks, and fix profhz if needed.
*/
i = stathz ? stathz : hz;
if (profhz == 0)
profhz = i;
psratio = profhz / i;
rrticks = hz / 10;
#ifdef NTP
switch (hz) {
case 1:
shifthz = SHIFT_SCALE - 0;
break;
case 2:
shifthz = SHIFT_SCALE - 1;
break;
case 4:
shifthz = SHIFT_SCALE - 2;
break;
case 8:
shifthz = SHIFT_SCALE - 3;
break;
case 16:
shifthz = SHIFT_SCALE - 4;
break;
case 32:
shifthz = SHIFT_SCALE - 5;
break;
case 60:
case 64:
shifthz = SHIFT_SCALE - 6;
break;
case 96:
case 100:
case 128:
shifthz = SHIFT_SCALE - 7;
break;
case 256:
shifthz = SHIFT_SCALE - 8;
break;
1997-05-05 23:25:26 +04:00
case 512:
shifthz = SHIFT_SCALE - 9;
break;
case 1000:
case 1024:
shifthz = SHIFT_SCALE - 10;
break;
case 1200:
case 2048:
shifthz = SHIFT_SCALE - 11;
break;
case 4096:
shifthz = SHIFT_SCALE - 12;
break;
case 8192:
shifthz = SHIFT_SCALE - 13;
break;
case 16384:
shifthz = SHIFT_SCALE - 14;
break;
case 32768:
shifthz = SHIFT_SCALE - 15;
break;
case 65536:
shifthz = SHIFT_SCALE - 16;
break;
default:
panic("weird hz");
}
if (fixtick == 0) {
/*
* Give MD code a chance to set this to a better
* value; but, if it doesn't, we should.
*/
fixtick = (1000000 - (hz*tick));
}
#endif
}
/*
* The real-time timer, interrupting hz times per second.
*/
void
2000-08-01 08:57:28 +04:00
hardclock(struct clockframe *frame)
{
2000-03-30 13:27:11 +04:00
struct proc *p;
int delta;
extern int tickdelta;
extern long timedelta;
struct cpu_info *ci = curcpu();
#ifdef NTP
2000-03-30 13:27:11 +04:00
int time_update;
int ltemp;
#endif
p = curproc;
if (p) {
2000-03-30 13:27:11 +04:00
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);
if ((--ci->ci_schedstate.spc_rrticks) <= 0)
roundrobin(ci);
#if defined(MULTIPROCESSOR)
/*
* If we are not the primary CPU, we're not allowed to do
* any more work.
*/
if (CPU_IS_PRIMARY(ci) == 0)
return;
#endif
/*
* 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;
#ifndef NTP
if (tickfix) {
tickfixcnt += tickfix;
if (tickfixcnt >= tickfixinterval) {
delta++;
tickfixcnt -= tickfixinterval;
}
}
#endif /* !NTP */
/* Imprecise 4bsd adjtime() handling */
if (timedelta != 0) {
delta += tickdelta;
timedelta -= tickdelta;
}
#ifdef notyet
microset();
#endif
#ifndef NTP
BUMPTIME(&time, delta); /* XXX Now done using NTP code below */
#endif
BUMPTIME(&mono_time, delta);
#ifdef NTP
1996-03-08 09:27:30 +03:00
time_update = delta;
/*
* 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;
}
#ifdef HIGHBALL
/*
* If the HIGHBALL board is installed, we need to adjust the
* external clock offset in order to close the hardware feedback
* loop. This will adjust the external clock phase and frequency
* in small amounts. The additional phase noise and frequency
* wander this causes should be minimal. We also need to
* discipline the kernel time variable, since the PLL is used to
* discipline the external clock. If the Highball board is not
* present, we discipline kernel time with the PLL as usual. We
* assume that the external clock phase adjustment (time_update)
* and kernel phase adjustment (clock_cpu) are less than the
* value of tick.
*/
clock_offset.tv_usec += time_update;
if (clock_offset.tv_usec >= 1000000) {
clock_offset.tv_sec++;
clock_offset.tv_usec -= 1000000;
}
if (clock_offset.tv_usec < 0) {
clock_offset.tv_sec--;
clock_offset.tv_usec += 1000000;
}
time.tv_usec += clock_cpu;
clock_cpu = 0;
#else
time.tv_usec += time_update;
#endif /* HIGHBALL */
/*
* 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 (time.tv_usec >= 1000000) {
time.tv_usec -= 1000000;
time.tv_sec++;
time_maxerror += time_tolerance >> SHIFT_USEC;
/*
* 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 (time.tv_sec % 86400 == 0) {
time.tv_sec--;
time_state = TIME_OOP;
}
break;
case TIME_DEL:
if ((time.tv_sec + 1) % 86400 == 0) {
time.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;
break;
}
/*
* 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 << (shifthz - SHIFT_UPDATE);
} else 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 << (shifthz - SHIFT_UPDATE);
} else
time_adj = 0;
/*
* 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 - shifthz);
else
time_adj += ltemp >> (SHIFT_USEC - shifthz);
time_adj += (long)fixtick << shifthz;
/*
* When the CPU clock oscillator frequency is not a
* power of 2 in Hz, shifthz is only an approximate
* scale factor.
*
* To determine the adjustment, you can do the following:
* bc -q
* scale=24
* obase=2
* idealhz/realhz
* where `idealhz' is the next higher power of 2, and `realhz'
* is the actual value. You may need to factor this result
* into a sequence of 2 multipliers to get better precision.
*
* Likewise, the error can be calculated with (e.g. for 100Hz):
* bc -q
* scale=24
* ((1+2^-2+2^-5)*(1-2^-10)*realhz-idealhz)/idealhz
* (and then multiply by 1000000 to get ppm).
*/
switch (hz) {
case 60:
/* A factor of 1.000100010001 gives about 15ppm
error. */
if (time_adj < 0) {
time_adj -= (-time_adj >> 4);
time_adj -= (-time_adj >> 8);
} else {
time_adj += (time_adj >> 4);
time_adj += (time_adj >> 8);
}
break;
case 96:
/* A factor of 1.0101010101 gives about 244ppm error. */
if (time_adj < 0) {
time_adj -= (-time_adj >> 2);
time_adj -= (-time_adj >> 4) + (-time_adj >> 8);
} else {
time_adj += (time_adj >> 2);
time_adj += (time_adj >> 4) + (time_adj >> 8);
}
break;
case 100:
/* A factor of 1.010001111010111 gives about 1ppm
error. */
if (time_adj < 0) {
time_adj -= (-time_adj >> 2) + (-time_adj >> 5);
time_adj += (-time_adj >> 10);
} else {
time_adj += (time_adj >> 2) + (time_adj >> 5);
time_adj -= (time_adj >> 10);
}
break;
case 1000:
/* A factor of 1.000001100010100001 gives about 50ppm
error. */
if (time_adj < 0) {
time_adj -= (-time_adj >> 6) + (-time_adj >> 11);
time_adj -= (-time_adj >> 7);
} else {
time_adj += (time_adj >> 6) + (time_adj >> 11);
time_adj += (time_adj >> 7);
}
break;
case 1200:
/* A factor of 1.1011010011100001 gives about 64ppm
error. */
if (time_adj < 0) {
time_adj -= (-time_adj >> 1) + (-time_adj >> 6);
time_adj -= (-time_adj >> 3) + (-time_adj >> 10);
} else {
time_adj += (time_adj >> 1) + (time_adj >> 6);
time_adj += (time_adj >> 3) + (time_adj >> 10);
}
break;
}
#ifdef EXT_CLOCK
/*
* If an external clock is present, it is necessary to
* discipline the kernel time variable anyway, since not
* all system components use the microtime() interface.
* Here, the time offset between the external clock and
* kernel time variable is computed every so often.
*/
clock_count++;
if (clock_count > CLOCK_INTERVAL) {
clock_count = 0;
microtime(&clock_ext);
delta.tv_sec = clock_ext.tv_sec - time.tv_sec;
delta.tv_usec = clock_ext.tv_usec -
time.tv_usec;
if (delta.tv_usec < 0)
delta.tv_sec--;
if (delta.tv_usec >= 500000) {
delta.tv_usec -= 1000000;
delta.tv_sec++;
}
if (delta.tv_usec < -500000) {
delta.tv_usec += 1000000;
delta.tv_sec--;
}
if (delta.tv_sec > 0 || (delta.tv_sec == 0 &&
delta.tv_usec > MAXPHASE) ||
delta.tv_sec < -1 || (delta.tv_sec == -1 &&
delta.tv_usec < -MAXPHASE)) {
time = clock_ext;
delta.tv_sec = 0;
delta.tv_usec = 0;
}
#ifdef HIGHBALL
clock_cpu = delta.tv_usec;
#else /* HIGHBALL */
hardupdate(delta.tv_usec);
#endif /* HIGHBALL */
}
#endif /* EXT_CLOCK */
}
#endif /* NTP */
/*
* Process callouts at a very low cpu priority, so we don't keep the
* relatively high clock interrupt priority any longer than necessary.
*/
simple_lock(&callwheel_slock); /* already at splclock() */
hardclock_ticks++;
if (! TAILQ_EMPTY(&callwheel[hardclock_ticks & callwheelmask].cq_q)) {
simple_unlock(&callwheel_slock);
if (CLKF_BASEPRI(frame)) {
/*
* Save the overhead of a software interrupt;
* it will happen as soon as we return, so do
* it now.
*
* NOTE: If we're at ``base priority'', softclock()
* was not already running.
*/
spllowersoftclock();
KERNEL_LOCK(LK_CANRECURSE|LK_EXCLUSIVE);
softclock(NULL);
KERNEL_UNLOCK();
} else {
#ifdef __HAVE_GENERIC_SOFT_INTERRUPTS
softintr_schedule(softclock_si);
#else
setsoftclock();
#endif
}
return;
} else if (softclock_running == 0 &&
(softclock_ticks + 1) == hardclock_ticks) {
softclock_ticks++;
}
simple_unlock(&callwheel_slock);
}
/*
* Software (low priority) clock interrupt.
* Run periodic events from timeout queue.
*/
/*ARGSUSED*/
void
softclock(void *v)
{
struct callout_queue *bucket;
struct callout *c;
2000-08-01 08:57:28 +04:00
void (*func)(void *);
void *arg;
int s, idx;
int steps = 0;
CALLWHEEL_LOCK(s);
softclock_running = 1;
#ifdef CALLWHEEL_STATS
callwheel_softclocks.ev_count++;
#endif
while (softclock_ticks != hardclock_ticks) {
softclock_ticks++;
idx = (int)(softclock_ticks & callwheelmask);
bucket = &callwheel[idx];
c = TAILQ_FIRST(&bucket->cq_q);
if (c == NULL) {
#ifdef CALLWHEEL_STATS
callwheel_softempty.ev_count++;
#endif
continue;
}
if (softclock_ticks < bucket->cq_hint) {
#ifdef CALLWHEEL_STATS
callwheel_hintworked.ev_count++;
#endif
continue;
}
bucket->cq_hint = UQUAD_MAX;
while (c != NULL) {
#ifdef CALLWHEEL_STATS
callwheel_softchecks.ev_count++;
#endif
if (c->c_time != softclock_ticks) {
if (c->c_time < bucket->cq_hint)
bucket->cq_hint = c->c_time;
c = TAILQ_NEXT(c, c_link);
if (++steps >= MAX_SOFTCLOCK_STEPS) {
nextsoftcheck = c;
/* Give interrupts a chance. */
CALLWHEEL_UNLOCK(s);
CALLWHEEL_LOCK(s);
c = nextsoftcheck;
steps = 0;
}
} else {
nextsoftcheck = TAILQ_NEXT(c, c_link);
TAILQ_REMOVE(&bucket->cq_q, c, c_link);
#ifdef CALLWHEEL_STATS
callwheel_sizes[idx]--;
callwheel_fired.ev_count++;
callwheel_count.ev_count--;
#endif
func = c->c_func;
arg = c->c_arg;
c->c_func = NULL;
c->c_flags &= ~CALLOUT_PENDING;
CALLWHEEL_UNLOCK(s);
(*func)(arg);
CALLWHEEL_LOCK(s);
steps = 0;
c = nextsoftcheck;
}
}
if (TAILQ_EMPTY(&bucket->cq_q))
bucket->cq_hint = UQUAD_MAX;
}
nextsoftcheck = NULL;
softclock_running = 0;
CALLWHEEL_UNLOCK(s);
}
/*
* callout_setsize:
*
* Determine how many callwheels are necessary and
* set hash mask. Called from allocsys().
*/
void
2000-08-01 08:57:28 +04:00
callout_setsize(void)
{
for (callwheelsize = 1; callwheelsize < ncallout; callwheelsize <<= 1)
/* loop */ ;
callwheelmask = callwheelsize - 1;
}
/*
* callout_startup:
*
* Initialize the callwheel buckets.
*/
void
2000-08-01 08:57:28 +04:00
callout_startup(void)
{
int i;
for (i = 0; i < callwheelsize; i++) {
callwheel[i].cq_hint = UQUAD_MAX;
TAILQ_INIT(&callwheel[i].cq_q);
}
simple_lock_init(&callwheel_slock);
#ifdef CALLWHEEL_STATS
evcnt_attach_dynamic(&callwheel_collisions, EVCNT_TYPE_MISC,
NULL, "callwheel", "collisions");
evcnt_attach_dynamic(&callwheel_maxlength, EVCNT_TYPE_MISC,
NULL, "callwheel", "maxlength");
evcnt_attach_dynamic(&callwheel_count, EVCNT_TYPE_MISC,
NULL, "callwheel", "count");
evcnt_attach_dynamic(&callwheel_established, EVCNT_TYPE_MISC,
NULL, "callwheel", "established");
evcnt_attach_dynamic(&callwheel_fired, EVCNT_TYPE_MISC,
NULL, "callwheel", "fired");
evcnt_attach_dynamic(&callwheel_disestablished, EVCNT_TYPE_MISC,
NULL, "callwheel", "disestablished");
evcnt_attach_dynamic(&callwheel_changed, EVCNT_TYPE_MISC,
NULL, "callwheel", "changed");
evcnt_attach_dynamic(&callwheel_softclocks, EVCNT_TYPE_MISC,
NULL, "callwheel", "softclocks");
evcnt_attach_dynamic(&callwheel_softempty, EVCNT_TYPE_MISC,
NULL, "callwheel", "softempty");
evcnt_attach_dynamic(&callwheel_hintworked, EVCNT_TYPE_MISC,
NULL, "callwheel", "hintworked");
#endif /* CALLWHEEL_STATS */
}
/*
* callout_init:
*
* Initialize a callout structure so that it can be used
* by callout_reset() and callout_stop().
*/
void
2000-08-01 08:57:28 +04:00
callout_init(struct callout *c)
{
memset(c, 0, sizeof(*c));
}
/*
* callout_reset:
*
* Establish or change a timeout.
*/
void
2000-08-01 08:57:28 +04:00
callout_reset(struct callout *c, int ticks, void (*func)(void *), void *arg)
{
struct callout_queue *bucket;
int s;
if (ticks <= 0)
ticks = 1;
CALLWHEEL_LOCK(s);
/*
* If this callout's timer is already running, cancel it
* before we modify it.
*/
if (c->c_flags & CALLOUT_PENDING) {
callout_stop_locked(c); /* Already locked */
#ifdef CALLWHEEL_STATS
callwheel_changed.ev_count++;
#endif
}
c->c_arg = arg;
c->c_func = func;
c->c_flags = CALLOUT_ACTIVE | CALLOUT_PENDING;
c->c_time = hardclock_ticks + ticks;
bucket = &callwheel[c->c_time & callwheelmask];
#ifdef CALLWHEEL_STATS
if (! TAILQ_EMPTY(&bucket->cq_q))
callwheel_collisions.ev_count++;
#endif
TAILQ_INSERT_TAIL(&bucket->cq_q, c, c_link);
if (c->c_time < bucket->cq_hint)
bucket->cq_hint = c->c_time;
#ifdef CALLWHEEL_STATS
callwheel_count.ev_count++;
callwheel_established.ev_count++;
if (++callwheel_sizes[c->c_time & callwheelmask] >
callwheel_maxlength.ev_count)
callwheel_maxlength.ev_count =
callwheel_sizes[c->c_time & callwheelmask];
#endif
CALLWHEEL_UNLOCK(s);
}
/*
* callout_stop_locked:
*
* Disestablish a timeout. Callwheel is locked.
*/
static void
callout_stop_locked(struct callout *c)
{
struct callout_queue *bucket;
/*
* Don't attempt to delete a callout that's not on the queue.
*/
if ((c->c_flags & CALLOUT_PENDING) == 0) {
c->c_flags &= ~CALLOUT_ACTIVE;
return;
}
c->c_flags &= ~(CALLOUT_ACTIVE | CALLOUT_PENDING);
if (nextsoftcheck == c)
nextsoftcheck = TAILQ_NEXT(c, c_link);
bucket = &callwheel[c->c_time & callwheelmask];
TAILQ_REMOVE(&bucket->cq_q, c, c_link);
if (TAILQ_EMPTY(&bucket->cq_q))
bucket->cq_hint = UQUAD_MAX;
#ifdef CALLWHEEL_STATS
callwheel_count.ev_count--;
callwheel_disestablished.ev_count++;
callwheel_sizes[c->c_time & callwheelmask]--;
#endif
c->c_func = NULL;
}
/*
* callout_stop:
*
* Disestablish a timeout. Callwheel is unlocked. This is
* the standard entry point.
*/
void
callout_stop(struct callout *c)
{
int s;
CALLWHEEL_LOCK(s);
callout_stop_locked(c);
CALLWHEEL_UNLOCK(s);
}
#ifdef CALLWHEEL_STATS
/*
* callout_showstats:
*
* Display callout statistics. Call it from DDB.
*/
void
2000-08-01 08:57:28 +04:00
callout_showstats(void)
{
u_int64_t curticks;
int s;
s = splclock();
curticks = softclock_ticks;
splx(s);
printf("Callwheel statistics:\n");
printf("\tCallouts currently queued: %llu\n",
(long long) callwheel_count.ev_count);
printf("\tCallouts established: %llu\n",
(long long) callwheel_established.ev_count);
printf("\tCallouts disestablished: %llu\n",
(long long) callwheel_disestablished.ev_count);
if (callwheel_changed.ev_count != 0)
printf("\t\tOf those, %llu were changes\n",
(long long) callwheel_changed.ev_count);
printf("\tCallouts that fired: %llu\n",
(long long) callwheel_fired.ev_count);
printf("\tNumber of buckets: %d\n", callwheelsize);
printf("\tNumber of hash collisions: %llu\n",
(long long) callwheel_collisions.ev_count);
printf("\tMaximum hash chain length: %llu\n",
(long long) callwheel_maxlength.ev_count);
printf("\tSoftclocks: %llu, Softchecks: %llu\n",
(long long) callwheel_softclocks.ev_count,
(long long) callwheel_softchecks.ev_count);
printf("\t\tEmpty buckets seen: %llu\n",
(long long) callwheel_softempty.ev_count);
printf("\t\tTimes hint saved scan: %llu\n",
(long long) callwheel_hintworked.ev_count);
}
#endif
/*
* Compute number of hz until specified time. Used to compute second
* argument to callout_reset() from an absolute time.
*/
int
2000-08-01 08:57:28 +04:00
hzto(struct timeval *tv)
{
unsigned long ticks;
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 assume that hz is integral.
*
* Otherwise, round the time difference down to the maximum
* representable value.
*
* If ints are 32-bit, 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 || (sec == 0 && usec <= 0)) {
/*
* Would expire now or in the past. Return 0 ticks.
* This is different from the legacy hzto() interface,
* and callers need to check for it.
*/
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
2000-08-01 08:57:28 +04:00
startprofclock(struct proc *p)
{
if ((p->p_flag & P_PROFIL) == 0) {
p->p_flag |= P_PROFIL;
/*
* This is only necessary if using the clock as the
* profiling source.
*/
if (++profprocs == 1 && stathz != 0)
psdiv = psratio;
}
}
/*
* Stop profiling on a process.
*/
void
2000-08-01 08:57:28 +04:00
stopprofclock(struct proc *p)
{
if (p->p_flag & P_PROFIL) {
p->p_flag &= ~P_PROFIL;
/*
* This is only necessary if using the clock as the
* profiling source.
*/
if (--profprocs == 0 && stathz != 0)
psdiv = 1;
}
}
#if defined(PERFCTRS)
/*
* Independent profiling "tick" in case we're using a separate
* clock or profiling event source. Currently, that's just
* performance counters--hence the wrapper.
*/
void
proftick(struct clockframe *frame)
{
#ifdef GPROF
struct gmonparam *g;
intptr_t i;
#endif
struct proc *p;
p = curproc;
if (CLKF_USERMODE(frame)) {
if (p->p_flag & P_PROFIL)
addupc_intr(p, CLKF_PC(frame));
} else {
#ifdef GPROF
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
#ifdef PROC_PC
if (p && p->p_flag & P_PROFIL)
addupc_intr(p, PROC_PC(p));
#endif
}
}
#endif
/*
* Statistics clock. Grab profile sample, and if divider reaches 0,
* do process and kernel statistics.
*/
void
2000-08-01 08:57:28 +04:00
statclock(struct clockframe *frame)
{
#ifdef GPROF
2000-03-30 13:27:11 +04:00
struct gmonparam *g;
intptr_t i;
#endif
struct cpu_info *ci = curcpu();
struct schedstate_percpu *spc = &ci->ci_schedstate;
2000-03-30 13:27:11 +04:00
struct proc *p;
/*
* 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);
}
}
p = curproc;
if (CLKF_USERMODE(frame)) {
if (p->p_flag & P_PROFIL && profsrc == PROFSRC_CLOCK)
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 (profsrc == PROFSRC_CLOCK && g->state == GMON_PROF_ON) {
i = CLKF_PC(frame) - g->lowpc;
if (i < g->textsize) {
i /= HISTFRACTION * sizeof(*g->kcount);
g->kcount[i]++;
}
}
#endif
#ifdef PROC_PC
if (p && profsrc == PROFSRC_CLOCK && 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) {
Scheduler bug fixes and reorganization * fix the ancient nice(1) bug, where nice +20 processes incorrectly steal 10 - 20% of the CPU, (or even more depending on load average) * provide a new schedclk() mechanism at a new clock at schedhz, so high platform hz values don't cause nice +0 processes to look like they are niced * change the algorithm slightly, and reorganize the code a lot * fix percent-CPU calculation bugs, and eliminate some no-op code === nice bug === Correctly divide the scheduler queues between niced and compute-bound processes. The current nice weight of two (sort of, see `algorithm change' below) neatly divides the USRPRI queues in half; this should have been used to clip p_estcpu, instead of UCHAR_MAX. Besides being the wrong amount, clipping an unsigned char to UCHAR_MAX is a no-op, and it was done after decay_cpu() which can only _reduce_ the value. It has to be kept <= NICE_WEIGHT * PRIO_MAX - PPQ or processes can scheduler-penalize themselves onto the same queue as nice +20 processes. (Or even a higher one.) === New schedclk() mechansism === Some platforms should be cutting down stathz before hitting the scheduler, since the scheduler algorithm only works right in the vicinity of 64 Hz. Rather than prescale hz, then scale back and forth by 4 every time p_estcpu is touched (each occurance an abstraction violation), use p_estcpu without scaling and require schedhz to be generated directly at the right frequency. Use a default stathz (well, actually, profhz) / 4, so nothing changes unless a platform defines schedhz and a new clock. Define these for alpha, where hz==1024, and nice was totally broke. === Algorithm change === The nice value used to be added to the exponentially-decayed scheduler history value p_estcpu, in _addition_ to be incorporated directly (with greater wieght) into the priority calculation. At first glance, it appears to be a pointless increase of 1/8 the nice effect (pri = p_estcpu/4 + nice*2), but it's actually at least 3x that because it will ramp up linearly but be decayed only exponentially, thus converging to an additional .75 nice for a loadaverage of one. I killed this, it makes the behavior hard to control, almost impossible to analyze, and the effect (~~nothing at for the first second, then somewhat increased niceness after three seconds or more, depending on load average) pointless. === Other bugs === hz -> profhz in the p_pctcpu = f(p_cpticks) calcuation. Collect scheduler functionality. Try to put each abstraction in just one place.
1999-02-23 05:56:03 +03:00
++p->p_cpticks;
/*
* If no separate schedclock is provided, call it here
* at ~~12-25 Hz, ~~16 Hz is best
Scheduler bug fixes and reorganization * fix the ancient nice(1) bug, where nice +20 processes incorrectly steal 10 - 20% of the CPU, (or even more depending on load average) * provide a new schedclk() mechanism at a new clock at schedhz, so high platform hz values don't cause nice +0 processes to look like they are niced * change the algorithm slightly, and reorganize the code a lot * fix percent-CPU calculation bugs, and eliminate some no-op code === nice bug === Correctly divide the scheduler queues between niced and compute-bound processes. The current nice weight of two (sort of, see `algorithm change' below) neatly divides the USRPRI queues in half; this should have been used to clip p_estcpu, instead of UCHAR_MAX. Besides being the wrong amount, clipping an unsigned char to UCHAR_MAX is a no-op, and it was done after decay_cpu() which can only _reduce_ the value. It has to be kept <= NICE_WEIGHT * PRIO_MAX - PPQ or processes can scheduler-penalize themselves onto the same queue as nice +20 processes. (Or even a higher one.) === New schedclk() mechansism === Some platforms should be cutting down stathz before hitting the scheduler, since the scheduler algorithm only works right in the vicinity of 64 Hz. Rather than prescale hz, then scale back and forth by 4 every time p_estcpu is touched (each occurance an abstraction violation), use p_estcpu without scaling and require schedhz to be generated directly at the right frequency. Use a default stathz (well, actually, profhz) / 4, so nothing changes unless a platform defines schedhz and a new clock. Define these for alpha, where hz==1024, and nice was totally broke. === Algorithm change === The nice value used to be added to the exponentially-decayed scheduler history value p_estcpu, in _addition_ to be incorporated directly (with greater wieght) into the priority calculation. At first glance, it appears to be a pointless increase of 1/8 the nice effect (pri = p_estcpu/4 + nice*2), but it's actually at least 3x that because it will ramp up linearly but be decayed only exponentially, thus converging to an additional .75 nice for a loadaverage of one. I killed this, it makes the behavior hard to control, almost impossible to analyze, and the effect (~~nothing at for the first second, then somewhat increased niceness after three seconds or more, depending on load average) pointless. === Other bugs === hz -> profhz in the p_pctcpu = f(p_cpticks) calcuation. Collect scheduler functionality. Try to put each abstraction in just one place.
1999-02-23 05:56:03 +03:00
*/
if (schedhz == 0)
if ((++ci->ci_schedstate.spc_schedticks & 3) == 0)
schedclock(p);
}
}
#ifdef NTP /* NTP phase-locked loop in kernel */
/*
* 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
2000-08-01 08:57:28 +04:00
hardupdate(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;
}
#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
2000-08-01 08:57:28 +04:00
hardpps(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 */
#endif /* NTP */
/*
* Return information about system clocks.
*/
1996-02-04 05:15:01 +03:00
int
2000-08-01 08:57:28 +04:00
sysctl_clockrate(void *where, size_t *sizep)
{
struct clockinfo clkinfo;
/*
* Construct clockinfo structure.
*/
clkinfo.tick = tick;
1994-09-19 01:55:43 +04:00
clkinfo.tickadj = tickadj;
clkinfo.hz = hz;
clkinfo.profhz = profhz;
clkinfo.stathz = stathz ? stathz : hz;
return (sysctl_rdstruct(where, sizep, NULL, &clkinfo, sizeof(clkinfo)));
}