530 lines
14 KiB
C
530 lines
14 KiB
C
/*-
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* Copyright (c) 1982, 1986, 1991, 1993
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* The Regents of the University of California. All rights reserved.
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* (c) UNIX System Laboratories, Inc.
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* All or some portions of this file are derived from material licensed
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* to the University of California by American Telephone and Telegraph
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* Co. or Unix System Laboratories, Inc. and are reproduced herein with
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* the permission of UNIX System Laboratories, Inc.
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*
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* Redistribution and use in source and binary forms, with or without
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* modification, are permitted provided that the following conditions
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* are met:
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* 1. Redistributions of source code must retain the above copyright
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* notice, this list of conditions and the following disclaimer.
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* 2. Redistributions in binary form must reproduce the above copyright
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* notice, this list of conditions and the following disclaimer in the
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* documentation and/or other materials provided with the distribution.
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* 3. All advertising materials mentioning features or use of this software
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* must display the following acknowledgement:
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* This product includes software developed by the University of
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* California, Berkeley and its contributors.
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* 4. Neither the name of the University nor the names of its contributors
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* may be used to endorse or promote products derived from this software
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* without specific prior written permission.
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*
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* THIS SOFTWARE IS PROVIDED BY THE REGENTS AND CONTRIBUTORS ``AS IS'' AND
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* ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
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* IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
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* ARE DISCLAIMED. IN NO EVENT SHALL THE REGENTS OR CONTRIBUTORS BE LIABLE
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* FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
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* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
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* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
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* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT
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* LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY
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* OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF
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* SUCH DAMAGE.
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*
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* @(#)kern_clock.c 8.5 (Berkeley) 1/21/94
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*/
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#include <sys/param.h>
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#include <sys/systm.h>
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#include <sys/dkstat.h>
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#include <sys/callout.h>
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#include <sys/kernel.h>
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#include <sys/proc.h>
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#include <sys/resourcevar.h>
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#include <machine/cpu.h>
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#ifdef GPROF
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#include <sys/gmon.h>
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#endif
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/*
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* Clock handling routines.
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*
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* This code is written to operate with two timers that run independently of
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* each other. The main clock, running hz times per second, is used to keep
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* track of real time. The second timer handles kernel and user profiling,
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* and does resource use estimation. If the second timer is programmable,
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* it is randomized to avoid aliasing between the two clocks. For example,
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* the randomization prevents an adversary from always giving up the cpu
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* just before its quantum expires. Otherwise, it would never accumulate
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* cpu ticks. The mean frequency of the second timer is stathz.
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*
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* If no second timer exists, stathz will be zero; in this case we drive
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* profiling and statistics off the main clock. This WILL NOT be accurate;
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* do not do it unless absolutely necessary.
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*
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* The statistics clock may (or may not) be run at a higher rate while
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* profiling. This profile clock runs at profhz. We require that profhz
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* be an integral multiple of stathz.
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*
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* If the statistics clock is running fast, it must be divided by the ratio
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* profhz/stathz for statistics. (For profiling, every tick counts.)
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*/
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/*
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* TODO:
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* allocate more timeout table slots when table overflows.
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*/
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/*
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* Bump a timeval by a small number of usec's.
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*/
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#define BUMPTIME(t, usec) { \
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register volatile struct timeval *tp = (t); \
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register long us; \
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\
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tp->tv_usec = us = tp->tv_usec + (usec); \
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if (us >= 1000000) { \
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tp->tv_usec = us - 1000000; \
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tp->tv_sec++; \
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} \
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}
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int stathz;
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int profhz;
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int profprocs;
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int ticks;
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static int psdiv, pscnt; /* prof => stat divider */
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int psratio; /* ratio: prof / stat */
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volatile struct timeval time;
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volatile struct timeval mono_time;
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/*
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* Initialize clock frequencies and start both clocks running.
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*/
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void
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initclocks()
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{
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register int i;
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/*
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* Set divisors to 1 (normal case) and let the machine-specific
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* code do its bit.
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*/
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psdiv = pscnt = 1;
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cpu_initclocks();
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/*
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* Compute profhz/stathz, and fix profhz if needed.
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*/
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i = stathz ? stathz : hz;
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if (profhz == 0)
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profhz = i;
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psratio = profhz / i;
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}
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/*
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* The real-time timer, interrupting hz times per second.
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*/
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void
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hardclock(frame)
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register struct clockframe *frame;
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{
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register struct callout *p1;
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register struct proc *p;
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register int delta, needsoft;
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extern int tickdelta;
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extern long timedelta;
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/*
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* Update real-time timeout queue.
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* At front of queue are some number of events which are ``due''.
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* The time to these is <= 0 and if negative represents the
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* number of ticks which have passed since it was supposed to happen.
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* The rest of the q elements (times > 0) are events yet to happen,
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* where the time for each is given as a delta from the previous.
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* Decrementing just the first of these serves to decrement the time
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* to all events.
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*/
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needsoft = 0;
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for (p1 = calltodo.c_next; p1 != NULL; p1 = p1->c_next) {
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if (--p1->c_time > 0)
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break;
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needsoft = 1;
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if (p1->c_time == 0)
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break;
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}
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p = curproc;
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if (p) {
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register struct pstats *pstats;
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/*
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* Run current process's virtual and profile time, as needed.
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*/
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pstats = p->p_stats;
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if (CLKF_USERMODE(frame) &&
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timerisset(&pstats->p_timer[ITIMER_VIRTUAL].it_value) &&
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itimerdecr(&pstats->p_timer[ITIMER_VIRTUAL], tick) == 0)
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psignal(p, SIGVTALRM);
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if (timerisset(&pstats->p_timer[ITIMER_PROF].it_value) &&
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itimerdecr(&pstats->p_timer[ITIMER_PROF], tick) == 0)
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psignal(p, SIGPROF);
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}
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/*
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* If no separate statistics clock is available, run it from here.
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*/
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if (stathz == 0)
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statclock(frame);
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/*
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* Increment the time-of-day. The increment is just ``tick'' unless
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* we are still adjusting the clock; see adjtime().
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*/
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ticks++;
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if (timedelta == 0)
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delta = tick;
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else {
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delta = tick + tickdelta;
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timedelta -= tickdelta;
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}
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BUMPTIME(&time, delta);
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BUMPTIME(&mono_time, delta);
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/*
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* Process callouts at a very low cpu priority, so we don't keep the
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* relatively high clock interrupt priority any longer than necessary.
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*/
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if (needsoft) {
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if (CLKF_BASEPRI(frame)) {
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/*
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* Save the overhead of a software interrupt;
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* it will happen as soon as we return, so do it now.
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*/
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(void)splsoftclock();
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softclock();
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} else
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setsoftclock();
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}
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}
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/*
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* Software (low priority) clock interrupt.
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* Run periodic events from timeout queue.
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*/
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/*ARGSUSED*/
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void
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softclock()
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{
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register struct callout *c;
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register void *arg;
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register void (*func) __P((void *));
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register int s;
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s = splhigh();
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while ((c = calltodo.c_next) != NULL && c->c_time <= 0) {
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func = c->c_func;
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arg = c->c_arg;
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calltodo.c_next = c->c_next;
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c->c_next = callfree;
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callfree = c;
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splx(s);
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(*func)(arg);
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(void) splhigh();
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}
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splx(s);
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}
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/*
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* timeout --
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* Execute a function after a specified length of time.
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*
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* untimeout --
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* Cancel previous timeout function call.
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*
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* See AT&T BCI Driver Reference Manual for specification. This
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* implementation differs from that one in that no identification
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* value is returned from timeout, rather, the original arguments
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* to timeout are used to identify entries for untimeout.
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*/
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void
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timeout(ftn, arg, ticks)
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void (*ftn) __P((void *));
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void *arg;
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register int ticks;
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{
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register struct callout *new, *p, *t;
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register int s;
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if (ticks <= 0)
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ticks = 1;
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/* Lock out the clock. */
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s = splhigh();
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/* Fill in the next free callout structure. */
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if (callfree == NULL)
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panic("timeout table full");
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new = callfree;
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callfree = new->c_next;
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new->c_arg = arg;
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new->c_func = ftn;
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/*
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* The time for each event is stored as a difference from the time
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* of the previous event on the queue. Walk the queue, correcting
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* the ticks argument for queue entries passed. Correct the ticks
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* value for the queue entry immediately after the insertion point
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* as well. Watch out for negative c_time values; these represent
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* overdue events.
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*/
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for (p = &calltodo;
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(t = p->c_next) != NULL && ticks > t->c_time; p = t)
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if (t->c_time > 0)
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ticks -= t->c_time;
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new->c_time = ticks;
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if (t != NULL)
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t->c_time -= ticks;
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/* Insert the new entry into the queue. */
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p->c_next = new;
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new->c_next = t;
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splx(s);
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}
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void
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untimeout(ftn, arg)
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void (*ftn) __P((void *));
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void *arg;
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{
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register struct callout *p, *t;
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register int s;
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s = splhigh();
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for (p = &calltodo; (t = p->c_next) != NULL; p = t)
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if (t->c_func == ftn && t->c_arg == arg) {
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/* Increment next entry's tick count. */
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if (t->c_next && t->c_time > 0)
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t->c_next->c_time += t->c_time;
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/* Move entry from callout queue to callfree queue. */
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p->c_next = t->c_next;
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t->c_next = callfree;
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callfree = t;
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break;
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}
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splx(s);
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}
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/*
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* Compute number of hz until specified time. Used to
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* compute third argument to timeout() from an absolute time.
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*/
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int
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hzto(tv)
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struct timeval *tv;
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{
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register long ticks, sec;
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int s;
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/*
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* If number of milliseconds will fit in 32 bit arithmetic,
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* then compute number of milliseconds to time and scale to
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* ticks. Otherwise just compute number of hz in time, rounding
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* times greater than representible to maximum value.
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*
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* Delta times less than 25 days can be computed ``exactly''.
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* Maximum value for any timeout in 10ms ticks is 250 days.
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*/
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s = splhigh();
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sec = tv->tv_sec - time.tv_sec;
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if (sec <= 0x7fffffff / 1000 - 1000)
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ticks = ((tv->tv_sec - time.tv_sec) * 1000 +
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(tv->tv_usec - time.tv_usec) / 1000) / (tick / 1000);
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else if (sec <= 0x7fffffff / hz)
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ticks = sec * hz;
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else
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ticks = 0x7fffffff;
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splx(s);
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return (ticks);
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}
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/*
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* Start profiling on a process.
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*
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* Kernel profiling passes proc0 which never exits and hence
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* keeps the profile clock running constantly.
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*/
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void
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startprofclock(p)
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register struct proc *p;
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{
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int s;
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if ((p->p_flag & P_PROFIL) == 0) {
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p->p_flag |= P_PROFIL;
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if (++profprocs == 1 && stathz != 0) {
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s = splstatclock();
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psdiv = pscnt = psratio;
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setstatclockrate(profhz);
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splx(s);
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}
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}
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}
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/*
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* Stop profiling on a process.
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*/
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void
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stopprofclock(p)
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register struct proc *p;
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{
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int s;
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if (p->p_flag & P_PROFIL) {
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p->p_flag &= ~P_PROFIL;
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if (--profprocs == 0 && stathz != 0) {
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s = splstatclock();
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psdiv = pscnt = 1;
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setstatclockrate(stathz);
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splx(s);
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}
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}
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}
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int dk_ndrive = DK_NDRIVE;
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/*
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* Statistics clock. Grab profile sample, and if divider reaches 0,
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* do process and kernel statistics.
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*/
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void
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statclock(frame)
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register struct clockframe *frame;
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{
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#ifdef GPROF
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register struct gmonparam *g;
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#endif
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register struct proc *p;
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register int i;
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if (CLKF_USERMODE(frame)) {
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p = curproc;
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if (p->p_flag & P_PROFIL)
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addupc_intr(p, CLKF_PC(frame), 1);
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if (--pscnt > 0)
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return;
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/*
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* Came from user mode; CPU was in user state.
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* If this process is being profiled record the tick.
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*/
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p->p_uticks++;
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if (p->p_nice > NZERO)
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cp_time[CP_NICE]++;
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else
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cp_time[CP_USER]++;
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} else {
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#ifdef GPROF
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/*
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* Kernel statistics are just like addupc_intr, only easier.
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*/
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g = &_gmonparam;
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if (g->state == GMON_PROF_ON) {
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i = CLKF_PC(frame) - g->lowpc;
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if (i < g->textsize) {
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i /= HISTFRACTION * sizeof(*g->kcount);
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g->kcount[i]++;
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}
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}
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#endif
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if (--pscnt > 0)
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return;
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/*
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* Came from kernel mode, so we were:
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* - handling an interrupt,
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* - doing syscall or trap work on behalf of the current
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* user process, or
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* - spinning in the idle loop.
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* Whichever it is, charge the time as appropriate.
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* Note that we charge interrupts to the current process,
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* regardless of whether they are ``for'' that process,
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* so that we know how much of its real time was spent
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* in ``non-process'' (i.e., interrupt) work.
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*/
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p = curproc;
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if (CLKF_INTR(frame)) {
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if (p != NULL)
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p->p_iticks++;
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cp_time[CP_INTR]++;
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} else if (p != NULL) {
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p->p_sticks++;
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cp_time[CP_SYS]++;
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} else
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cp_time[CP_IDLE]++;
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}
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pscnt = psdiv;
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/*
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* We maintain statistics shown by user-level statistics
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* programs: the amount of time in each cpu state, and
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* the amount of time each of DK_NDRIVE ``drives'' is busy.
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*
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* XXX should either run linked list of drives, or (better)
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* grab timestamps in the start & done code.
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*/
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for (i = 0; i < DK_NDRIVE; i++)
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if (dk_busy & (1 << i))
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dk_time[i]++;
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/*
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* We adjust the priority of the current process. The priority of
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* a process gets worse as it accumulates CPU time. The cpu usage
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* estimator (p_estcpu) is increased here. The formula for computing
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* priorities (in kern_synch.c) will compute a different value each
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* time p_estcpu increases by 4. The cpu usage estimator ramps up
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* quite quickly when the process is running (linearly), and decays
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* away exponentially, at a rate which is proportionally slower when
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* the system is busy. The basic principal is that the system will
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* 90% forget that the process used a lot of CPU time in 5 * loadav
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* seconds. This causes the system to favor processes which haven't
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* run much recently, and to round-robin among other processes.
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*/
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if (p != NULL) {
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p->p_cpticks++;
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if (++p->p_estcpu == 0)
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p->p_estcpu--;
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if ((p->p_estcpu & 3) == 0) {
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resetpriority(p);
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if (p->p_priority >= PUSER)
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p->p_priority = p->p_usrpri;
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}
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}
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}
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/*
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* Return information about system clocks.
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*/
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int
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sysctl_clockrate(where, sizep)
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register char *where;
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size_t *sizep;
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{
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struct clockinfo clkinfo;
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/*
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* Construct clockinfo structure.
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*/
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clkinfo.hz = hz;
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clkinfo.tick = tick;
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clkinfo.profhz = profhz;
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clkinfo.stathz = stathz ? stathz : hz;
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return (sysctl_rdstruct(where, sizep, NULL, &clkinfo, sizeof(clkinfo)));
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}
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