40acdeabab
- Protect the cp_time tick counts with atomics instead of a global lock. There will only be one atomic per tick and this allows all processors to execute softclock concurrently. - In softclock, protect access to rusage and td_*tick data with the thread_lock(), expanding the scope of the thread lock over the whole function. - Do some creative re-arranging in hardclock() to avoid excess locking. - Protect the p_timer fields with the per-process spinlock. Tested by: kris, current@ Tested on: i386, amd64, ULE, 4BSD, libthr, libkse, PREEMPTION, etc. Discussed with: kris, attilio, kmacy, jhb, julian, bde (small parts each)
588 lines
15 KiB
C
588 lines
15 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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* 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/cdefs.h>
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__FBSDID("$FreeBSD$");
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#include "opt_kdb.h"
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#include "opt_device_polling.h"
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#include "opt_hwpmc_hooks.h"
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#include "opt_ntp.h"
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#include "opt_watchdog.h"
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#include <sys/param.h>
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#include <sys/systm.h>
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#include <sys/callout.h>
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#include <sys/kdb.h>
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#include <sys/kernel.h>
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#include <sys/lock.h>
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#include <sys/ktr.h>
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#include <sys/mutex.h>
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#include <sys/proc.h>
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#include <sys/resource.h>
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#include <sys/resourcevar.h>
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#include <sys/sched.h>
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#include <sys/signalvar.h>
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#include <sys/smp.h>
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#include <vm/vm.h>
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#include <vm/pmap.h>
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#include <vm/vm_map.h>
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#include <sys/sysctl.h>
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#include <sys/bus.h>
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#include <sys/interrupt.h>
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#include <sys/limits.h>
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#include <sys/timetc.h>
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#ifdef GPROF
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#include <sys/gmon.h>
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#endif
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#ifdef HWPMC_HOOKS
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#include <sys/pmckern.h>
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#endif
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#ifdef DEVICE_POLLING
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extern void hardclock_device_poll(void);
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#endif /* DEVICE_POLLING */
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static void initclocks(void *dummy);
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SYSINIT(clocks, SI_SUB_CLOCKS, SI_ORDER_FIRST, initclocks, NULL)
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/* Some of these don't belong here, but it's easiest to concentrate them. */
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long cp_time[CPUSTATES];
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/* Spin-lock protecting profiling statistics. */
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struct mtx time_lock;
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static int
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sysctl_kern_cp_time(SYSCTL_HANDLER_ARGS)
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{
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int error;
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#ifdef SCTL_MASK32
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int i;
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unsigned int cp_time32[CPUSTATES];
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if (req->flags & SCTL_MASK32) {
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if (!req->oldptr)
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return SYSCTL_OUT(req, 0, sizeof(cp_time32));
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for (i = 0; i < CPUSTATES; i++)
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cp_time32[i] = (unsigned int)cp_time[i];
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error = SYSCTL_OUT(req, cp_time32, sizeof(cp_time32));
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} else
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#endif
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{
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if (!req->oldptr)
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return SYSCTL_OUT(req, 0, sizeof(cp_time));
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error = SYSCTL_OUT(req, cp_time, sizeof(cp_time));
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}
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return error;
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}
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SYSCTL_PROC(_kern, OID_AUTO, cp_time, CTLTYPE_LONG|CTLFLAG_RD,
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0,0, sysctl_kern_cp_time, "LU", "CPU time statistics");
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#ifdef SW_WATCHDOG
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#include <sys/watchdog.h>
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static int watchdog_ticks;
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static int watchdog_enabled;
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static void watchdog_fire(void);
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static void watchdog_config(void *, u_int, int *);
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#endif /* SW_WATCHDOG */
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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.
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*
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* The main timer, running hz times per second, is used to trigger interval
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* timers, timeouts and rescheduling as needed.
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*
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* 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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* Time-of-day is maintained using a "timecounter", which may or may
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* not be related to the hardware generating the above mentioned
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* interrupts.
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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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int psratio;
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/*
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* Initialize clock frequencies and start both clocks running.
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*/
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/* ARGSUSED*/
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static void
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initclocks(dummy)
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void *dummy;
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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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mtx_init(&time_lock, "time lock", NULL, MTX_SPIN);
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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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#ifdef SW_WATCHDOG
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EVENTHANDLER_REGISTER(watchdog_list, watchdog_config, NULL, 0);
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#endif
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}
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/*
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* Each time the real-time timer fires, this function is called on all CPUs.
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* Note that hardclock() calls hardclock_cpu() for the boot CPU, so only
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* the other CPUs in the system need to call this function.
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*/
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void
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hardclock_cpu(int usermode)
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{
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struct pstats *pstats;
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struct thread *td = curthread;
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struct proc *p = td->td_proc;
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int ast;
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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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ast = 0;
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if (usermode &&
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timevalisset(&pstats->p_timer[ITIMER_VIRTUAL].it_value)) {
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PROC_SLOCK(p);
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if (itimerdecr(&pstats->p_timer[ITIMER_VIRTUAL], tick) == 0) {
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p->p_sflag |= PS_ALRMPEND;
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ast = 1;
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}
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PROC_SUNLOCK(p);
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}
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if (timevalisset(&pstats->p_timer[ITIMER_PROF].it_value)) {
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PROC_SLOCK(p);
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if (itimerdecr(&pstats->p_timer[ITIMER_PROF], tick) == 0) {
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p->p_sflag |= PS_PROFPEND;
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ast = 1;
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}
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PROC_SUNLOCK(p);
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}
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thread_lock(td);
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sched_tick();
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if (ast)
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td->td_flags |= TDF_ASTPENDING;
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thread_unlock(td);
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#ifdef HWPMC_HOOKS
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if (PMC_CPU_HAS_SAMPLES(PCPU_GET(cpuid)))
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PMC_CALL_HOOK_UNLOCKED(curthread, PMC_FN_DO_SAMPLES, NULL);
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#endif
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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(int usermode, uintfptr_t pc)
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{
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int need_softclock = 0;
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hardclock_cpu(usermode);
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tc_ticktock();
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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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* XXX: this only works for UP
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*/
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if (stathz == 0) {
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profclock(usermode, pc);
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statclock(usermode);
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}
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#ifdef DEVICE_POLLING
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hardclock_device_poll(); /* this is very short and quick */
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#endif /* DEVICE_POLLING */
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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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mtx_lock_spin_flags(&callout_lock, MTX_QUIET);
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ticks++;
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if (!TAILQ_EMPTY(&callwheel[ticks & callwheelmask])) {
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need_softclock = 1;
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} else if (softticks + 1 == ticks)
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++softticks;
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mtx_unlock_spin_flags(&callout_lock, MTX_QUIET);
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/*
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* swi_sched acquires the thread lock, so we don't want to call it
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* with callout_lock held; incorrect locking order.
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*/
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if (need_softclock)
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swi_sched(softclock_ih, 0);
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#ifdef SW_WATCHDOG
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if (watchdog_enabled > 0 && --watchdog_ticks <= 0)
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watchdog_fire();
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#endif /* SW_WATCHDOG */
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}
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/*
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* Compute number of ticks in the specified amount of time.
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*/
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int
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tvtohz(tv)
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struct timeval *tv;
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{
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register unsigned long ticks;
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register long sec, usec;
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/*
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* If the number of usecs in the whole seconds part of the time
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* difference fits in a long, then the total number of usecs will
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* fit in an unsigned long. Compute the total and convert it to
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* ticks, rounding up and adding 1 to allow for the current tick
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* to expire. Rounding also depends on unsigned long arithmetic
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* to avoid overflow.
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*
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* Otherwise, if the number of ticks in the whole seconds part of
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* the time difference fits in a long, then convert the parts to
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* ticks separately and add, using similar rounding methods and
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* overflow avoidance. This method would work in the previous
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* case but it is slightly slower and assumes that hz is integral.
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*
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* Otherwise, round the time difference down to the maximum
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* representable value.
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*
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* If ints have 32 bits, then the maximum value for any timeout in
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* 10ms ticks is 248 days.
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*/
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sec = tv->tv_sec;
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usec = tv->tv_usec;
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if (usec < 0) {
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sec--;
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usec += 1000000;
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}
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if (sec < 0) {
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#ifdef DIAGNOSTIC
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if (usec > 0) {
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sec++;
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usec -= 1000000;
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}
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printf("tvotohz: negative time difference %ld sec %ld usec\n",
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sec, usec);
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#endif
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ticks = 1;
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} else if (sec <= LONG_MAX / 1000000)
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ticks = (sec * 1000000 + (unsigned long)usec + (tick - 1))
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/ tick + 1;
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else if (sec <= LONG_MAX / hz)
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ticks = sec * hz
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+ ((unsigned long)usec + (tick - 1)) / tick + 1;
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else
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ticks = LONG_MAX;
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if (ticks > INT_MAX)
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ticks = INT_MAX;
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return ((int)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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PROC_LOCK_ASSERT(p, MA_OWNED);
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if (p->p_flag & P_STOPPROF)
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return;
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if ((p->p_flag & P_PROFIL) == 0) {
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p->p_flag |= P_PROFIL;
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mtx_lock_spin(&time_lock);
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if (++profprocs == 1)
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cpu_startprofclock();
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mtx_unlock_spin(&time_lock);
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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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PROC_LOCK_ASSERT(p, MA_OWNED);
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if (p->p_flag & P_PROFIL) {
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if (p->p_profthreads != 0) {
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p->p_flag |= P_STOPPROF;
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while (p->p_profthreads != 0)
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msleep(&p->p_profthreads, &p->p_mtx, PPAUSE,
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"stopprof", 0);
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p->p_flag &= ~P_STOPPROF;
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}
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if ((p->p_flag & P_PROFIL) == 0)
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return;
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p->p_flag &= ~P_PROFIL;
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mtx_lock_spin(&time_lock);
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if (--profprocs == 0)
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cpu_stopprofclock();
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mtx_unlock_spin(&time_lock);
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}
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}
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/*
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* Statistics clock. Updates rusage information and calls the scheduler
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* to adjust priorities of the active thread.
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*
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* This should be called by all active processors.
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*/
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void
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statclock(int usermode)
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{
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struct rusage *ru;
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struct vmspace *vm;
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struct thread *td;
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struct proc *p;
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long rss;
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td = curthread;
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p = td->td_proc;
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thread_lock_flags(td, MTX_QUIET);
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if (usermode) {
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/*
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* Charge the time as appropriate.
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*/
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#ifdef KSE
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if (p->p_flag & P_SA)
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thread_statclock(1);
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#endif
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td->td_uticks++;
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if (p->p_nice > NZERO)
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atomic_add_long(&cp_time[CP_NICE], 1);
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else
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atomic_add_long(&cp_time[CP_USER], 1);
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} else {
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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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if ((td->td_pflags & TDP_ITHREAD) ||
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td->td_intr_nesting_level >= 2) {
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td->td_iticks++;
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atomic_add_long(&cp_time[CP_INTR], 1);
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} else {
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#ifdef KSE
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if (p->p_flag & P_SA)
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thread_statclock(0);
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#endif
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td->td_pticks++;
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td->td_sticks++;
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if (!TD_IS_IDLETHREAD(td))
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atomic_add_long(&cp_time[CP_SYS], 1);
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else
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atomic_add_long(&cp_time[CP_IDLE], 1);
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}
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}
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/* Update resource usage integrals and maximums. */
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MPASS(p->p_vmspace != NULL);
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vm = p->p_vmspace;
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ru = &td->td_ru;
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ru->ru_ixrss += pgtok(vm->vm_tsize);
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ru->ru_idrss += pgtok(vm->vm_dsize);
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ru->ru_isrss += pgtok(vm->vm_ssize);
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rss = pgtok(vmspace_resident_count(vm));
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if (ru->ru_maxrss < rss)
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ru->ru_maxrss = rss;
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CTR4(KTR_SCHED, "statclock: %p(%s) prio %d stathz %d",
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td, td->td_proc->p_comm, td->td_priority, (stathz)?stathz:hz);
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sched_clock(td);
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thread_unlock(td);
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}
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void
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profclock(int usermode, uintfptr_t pc)
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{
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struct thread *td;
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#ifdef GPROF
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struct gmonparam *g;
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uintfptr_t i;
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#endif
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td = curthread;
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if (usermode) {
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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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* if there is no related user location yet, don't
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* bother trying to count it.
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*/
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if (td->td_proc->p_flag & P_PROFIL)
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addupc_intr(td, pc, 1);
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}
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#ifdef GPROF
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else {
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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 && pc >= g->lowpc) {
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i = PC_TO_I(g, pc);
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if (i < g->textsize) {
|
|
KCOUNT(g, i)++;
|
|
}
|
|
}
|
|
}
|
|
#endif
|
|
}
|
|
|
|
/*
|
|
* 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");
|
|
|
|
#ifdef SW_WATCHDOG
|
|
|
|
static void
|
|
watchdog_config(void *unused __unused, u_int cmd, int *error)
|
|
{
|
|
u_int u;
|
|
|
|
u = cmd & WD_INTERVAL;
|
|
if (u >= WD_TO_1SEC) {
|
|
watchdog_ticks = (1 << (u - WD_TO_1SEC)) * hz;
|
|
watchdog_enabled = 1;
|
|
*error = 0;
|
|
} else {
|
|
watchdog_enabled = 0;
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Handle a watchdog timeout by dumping interrupt information and
|
|
* then either dropping to DDB or panicking.
|
|
*/
|
|
static void
|
|
watchdog_fire(void)
|
|
{
|
|
int nintr;
|
|
u_int64_t inttotal;
|
|
u_long *curintr;
|
|
char *curname;
|
|
|
|
curintr = intrcnt;
|
|
curname = intrnames;
|
|
inttotal = 0;
|
|
nintr = eintrcnt - intrcnt;
|
|
|
|
printf("interrupt total\n");
|
|
while (--nintr >= 0) {
|
|
if (*curintr)
|
|
printf("%-12s %20lu\n", curname, *curintr);
|
|
curname += strlen(curname) + 1;
|
|
inttotal += *curintr++;
|
|
}
|
|
printf("Total %20ju\n", (uintmax_t)inttotal);
|
|
|
|
#if defined(KDB) && !defined(KDB_UNATTENDED)
|
|
kdb_backtrace();
|
|
kdb_enter("watchdog timeout");
|
|
#else
|
|
panic("watchdog timeout");
|
|
#endif
|
|
}
|
|
|
|
#endif /* SW_WATCHDOG */
|