freebsd-dev/sys/kern/kern_clock.c
Poul-Henning Kamp e7fa55af89 Give up on calling tc_ticktock() from a timeout, we have timeout
functions which run for several milliseconds at a time and getting
in queue behind one or more of those makes us miss our rewind.

Instead call it from hardclock() like we used to do, but retain the
prescaler so we still cope with high HZ values.
2002-09-04 10:15:19 +00:00

495 lines
14 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
* $FreeBSD$
*/
#include "opt_ntp.h"
#include <sys/param.h>
#include <sys/systm.h>
#include <sys/dkstat.h>
#include <sys/callout.h>
#include <sys/kernel.h>
#include <sys/lock.h>
#include <sys/ktr.h>
#include <sys/mutex.h>
#include <sys/proc.h>
#include <sys/resourcevar.h>
#include <sys/signalvar.h>
#include <sys/smp.h>
#include <vm/vm.h>
#include <vm/pmap.h>
#include <vm/vm_map.h>
#include <sys/sysctl.h>
#include <sys/bus.h>
#include <sys/interrupt.h>
#include <sys/timetc.h>
#include <machine/cpu.h>
#include <machine/limits.h>
#ifdef GPROF
#include <sys/gmon.h>
#endif
#ifdef DEVICE_POLLING
extern void init_device_poll(void);
extern void hardclock_device_poll(void);
#endif /* DEVICE_POLLING */
static void initclocks(void *dummy);
SYSINIT(clocks, SI_SUB_CLOCKS, SI_ORDER_FIRST, initclocks, NULL)
/* Some of these don't belong here, but it's easiest to concentrate them. */
long cp_time[CPUSTATES];
SYSCTL_OPAQUE(_kern, OID_AUTO, cp_time, CTLFLAG_RD, &cp_time, sizeof(cp_time),
"LU", "CPU time statistics");
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 timer, running hz times per second, is used to trigger interval
* timers, timeouts and rescheduling as needed.
*
* 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.)
*
* Time-of-day is maintained using a "timecounter", which may or may
* not be related to the hardware generating the above mentioned
* interrupts.
*/
int stathz;
int profhz;
static int profprocs;
int ticks;
static int psdiv, pscnt; /* prof => stat divider */
int psratio; /* ratio: prof / stat */
/*
* 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();
#ifdef DEVICE_POLLING
init_device_poll();
#endif
/*
* Compute profhz/stathz, and fix profhz if needed.
*/
i = stathz ? stathz : hz;
if (profhz == 0)
profhz = i;
psratio = profhz / i;
}
/*
* Each time the real-time timer fires, this function is called on all CPUs
* with each CPU passing in its curthread as the first argument. If possible
* a nice optimization in the future would be to allow the CPU receiving the
* actual real-time timer interrupt to call this function on behalf of the
* other CPUs rather than sending an IPI to all other CPUs so that they
* can call this function. Note that hardclock() calls hardclock_process()
* for the CPU receiving the timer interrupt, so only the other CPUs in the
* system need to call this function (or have it called on their behalf.
*/
void
hardclock_process(td, user)
struct thread *td;
int user;
{
struct pstats *pstats;
struct proc *p = td->td_proc;
/*
* Run current process's virtual and profile time, as needed.
*/
mtx_assert(&sched_lock, MA_OWNED);
if (p->p_flag & P_KSES) {
/* XXXKSE What to do? */
} else {
pstats = p->p_stats;
if (user &&
timevalisset(&pstats->p_timer[ITIMER_VIRTUAL].it_value) &&
itimerdecr(&pstats->p_timer[ITIMER_VIRTUAL], tick) == 0) {
p->p_sflag |= PS_ALRMPEND;
td->td_kse->ke_flags |= KEF_ASTPENDING;
}
if (timevalisset(&pstats->p_timer[ITIMER_PROF].it_value) &&
itimerdecr(&pstats->p_timer[ITIMER_PROF], tick) == 0) {
p->p_sflag |= PS_PROFPEND;
td->td_kse->ke_flags |= KEF_ASTPENDING;
}
}
}
/*
* The real-time timer, interrupting hz times per second.
*/
void
hardclock(frame)
register struct clockframe *frame;
{
int need_softclock = 0;
CTR0(KTR_CLK, "hardclock fired");
mtx_lock_spin_flags(&sched_lock, MTX_QUIET);
hardclock_process(curthread, CLKF_USERMODE(frame));
mtx_unlock_spin_flags(&sched_lock, MTX_QUIET);
tc_ticktock();
/*
* If no separate statistics clock is available, run it from here.
*
* XXX: this only works for UP
*/
if (stathz == 0)
statclock(frame);
#ifdef DEVICE_POLLING
hardclock_device_poll(); /* this is very short and quick */
#endif /* DEVICE_POLLING */
/*
* Process callouts at a very low cpu priority, so we don't keep the
* relatively high clock interrupt priority any longer than necessary.
*/
mtx_lock_spin_flags(&callout_lock, MTX_QUIET);
ticks++;
if (TAILQ_FIRST(&callwheel[ticks & callwheelmask]) != NULL) {
need_softclock = 1;
} else if (softticks + 1 == ticks)
++softticks;
mtx_unlock_spin_flags(&callout_lock, MTX_QUIET);
/*
* swi_sched acquires sched_lock, so we don't want to call it with
* callout_lock held; incorrect locking order.
*/
if (need_softclock)
swi_sched(softclock_ih, 0);
}
/*
* Compute number of ticks in the specified amount of time.
*/
int
tvtohz(tv)
struct timeval *tv;
{
register unsigned long ticks;
register long sec, usec;
/*
* If the number of usecs in the whole seconds part of the time
* difference fits in a long, then the total number of usecs will
* fit in an unsigned long. Compute the total and convert it to
* ticks, rounding up and adding 1 to allow for the current tick
* to expire. Rounding also depends on unsigned long arithmetic
* to avoid overflow.
*
* Otherwise, if the number of ticks in the whole seconds part of
* the time difference fits in a long, then convert the parts to
* ticks separately and add, using similar rounding methods and
* overflow avoidance. This method would work in the previous
* case but it is slightly slower and assumes that hz is integral.
*
* Otherwise, round the time difference down to the maximum
* representable value.
*
* If ints have 32 bits, then the maximum value for any timeout in
* 10ms ticks is 248 days.
*/
sec = tv->tv_sec;
usec = tv->tv_usec;
if (usec < 0) {
sec--;
usec += 1000000;
}
if (sec < 0) {
#ifdef DIAGNOSTIC
if (usec > 0) {
sec++;
usec -= 1000000;
}
printf("tvotohz: 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 ((int)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;
/*
* XXX; Right now sched_lock protects statclock(), but perhaps
* it should be protected later on by a time_lock, which would
* cover psdiv, etc. as well.
*/
mtx_lock_spin(&sched_lock);
if ((p->p_sflag & PS_PROFIL) == 0) {
p->p_sflag |= PS_PROFIL;
if (++profprocs == 1 && stathz != 0) {
s = splstatclock();
psdiv = pscnt = psratio;
setstatclockrate(profhz);
splx(s);
}
}
mtx_unlock_spin(&sched_lock);
}
/*
* Stop profiling on a process.
*/
void
stopprofclock(p)
register struct proc *p;
{
int s;
mtx_lock_spin(&sched_lock);
if (p->p_sflag & PS_PROFIL) {
p->p_sflag &= ~PS_PROFIL;
if (--profprocs == 0 && stathz != 0) {
s = splstatclock();
psdiv = pscnt = 1;
setstatclockrate(stathz);
splx(s);
}
}
mtx_unlock_spin(&sched_lock);
}
/*
* Do process and kernel statistics. Most of the statistics are only
* used by user-level statistics programs. The main exceptions are
* ke->ke_uticks, p->p_sticks, p->p_iticks, and p->p_estcpu. This function
* should be called by all CPUs in the system for each statistics clock
* interrupt. See the description of hardclock_process for more detail on
* this function's relationship to statclock.
*/
void
statclock_process(ke, pc, user)
struct kse *ke;
register_t pc;
int user;
{
#ifdef GPROF
struct gmonparam *g;
int i;
#endif
struct pstats *pstats;
long rss;
struct rusage *ru;
struct vmspace *vm;
struct proc *p = ke->ke_proc;
struct thread *td = ke->ke_thread; /* current thread */
KASSERT(ke == curthread->td_kse, ("statclock_process: td != curthread"));
mtx_assert(&sched_lock, MA_OWNED);
if (user) {
/*
* Came from user mode; CPU was in user state.
* If this process is being profiled, record the tick.
*/
if (p->p_sflag & PS_PROFIL)
addupc_intr(ke, pc, 1);
if (pscnt < psdiv)
return;
/*
* Charge the time as appropriate.
*/
ke->ke_uticks++;
if (ke->ke_ksegrp->kg_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 = pc - g->lowpc;
if (i < g->textsize) {
i /= HISTFRACTION * sizeof(*g->kcount);
g->kcount[i]++;
}
}
#endif
if (pscnt < psdiv)
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 ((td->td_ithd != NULL) || td->td_intr_nesting_level >= 2) {
ke->ke_iticks++;
cp_time[CP_INTR]++;
} else {
ke->ke_sticks++;
if (p != PCPU_GET(idlethread)->td_proc)
cp_time[CP_SYS]++;
else
cp_time[CP_IDLE]++;
}
}
schedclock(ke->ke_thread);
/* 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 += pgtok(vm->vm_tsize);
ru->ru_idrss += pgtok(vm->vm_dsize);
ru->ru_isrss += pgtok(vm->vm_ssize);
rss = pgtok(vmspace_resident_count(vm));
if (ru->ru_maxrss < rss)
ru->ru_maxrss = rss;
}
}
/*
* Statistics clock. Grab profile sample, and if divider reaches 0,
* do process and kernel statistics. Most of the statistics are only
* used by user-level statistics programs. The main exceptions are
* ke->ke_uticks, p->p_sticks, p->p_iticks, and p->p_estcpu.
*/
void
statclock(frame)
register struct clockframe *frame;
{
CTR0(KTR_CLK, "statclock fired");
mtx_lock_spin_flags(&sched_lock, MTX_QUIET);
if (--pscnt == 0)
pscnt = psdiv;
statclock_process(curthread->td_kse, CLKF_PC(frame), CLKF_USERMODE(frame));
mtx_unlock_spin_flags(&sched_lock, MTX_QUIET);
}
/*
* Return information about system clocks.
*/
static int
sysctl_kern_clockrate(SYSCTL_HANDLER_ARGS)
{
struct clockinfo clkinfo;
/*
* Construct clockinfo structure.
*/
bzero(&clkinfo, sizeof(clkinfo));
clkinfo.hz = hz;
clkinfo.tick = tick;
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",
"Rate and period of various kernel clocks");