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Annotation of kernel/kern/mach_clock.c, revision 1.1

1.1     ! root        1: /*
        !             2:  * Copyright (c) 1999 Apple Computer, Inc. All rights reserved.
        !             3:  *
        !             4:  * @APPLE_LICENSE_HEADER_START@
        !             5:  * 
        !             6:  * Portions Copyright (c) 1999 Apple Computer, Inc.  All Rights
        !             7:  * Reserved.  This file contains Original Code and/or Modifications of
        !             8:  * Original Code as defined in and that are subject to the Apple Public
        !             9:  * Source License Version 1.1 (the "License").  You may not use this file
        !            10:  * except in compliance with the License.  Please obtain a copy of the
        !            11:  * License at http://www.apple.com/publicsource and read it before using
        !            12:  * this file.
        !            13:  * 
        !            14:  * The Original Code and all software distributed under the License are
        !            15:  * distributed on an "AS IS" basis, WITHOUT WARRANTY OF ANY KIND, EITHER
        !            16:  * EXPRESS OR IMPLIED, AND APPLE HEREBY DISCLAIMS ALL SUCH WARRANTIES,
        !            17:  * INCLUDING WITHOUT LIMITATION, ANY WARRANTIES OF MERCHANTABILITY,
        !            18:  * FITNESS FOR A PARTICULAR PURPOSE OR NON-INFRINGEMENT.  Please see the
        !            19:  * License for the specific language governing rights and limitations
        !            20:  * under the License.
        !            21:  * 
        !            22:  * @APPLE_LICENSE_HEADER_END@
        !            23:  */
        !            24: 
        !            25: /* 
        !            26:  * Mach Operating System
        !            27:  * Copyright (c) 1991,1990,1989,1988 Carnegie Mellon University
        !            28:  * All Rights Reserved.
        !            29:  * 
        !            30:  * Permission to use, copy, modify and distribute this software and its
        !            31:  * documentation is hereby granted, provided that both the copyright
        !            32:  * notice and this permission notice appear in all copies of the
        !            33:  * software, derivative works or modified versions, and any portions
        !            34:  * thereof, and that both notices appear in supporting documentation.
        !            35:  * 
        !            36:  * CARNEGIE MELLON ALLOWS FREE USE OF THIS SOFTWARE IN ITS "AS IS"
        !            37:  * CONDITION.  CARNEGIE MELLON DISCLAIMS ANY LIABILITY OF ANY KIND FOR
        !            38:  * ANY DAMAGES WHATSOEVER RESULTING FROM THE USE OF THIS SOFTWARE.
        !            39:  * 
        !            40:  * Carnegie Mellon requests users of this software to return to
        !            41:  * 
        !            42:  *  Software Distribution Coordinator  or  [email protected]
        !            43:  *  School of Computer Science
        !            44:  *  Carnegie Mellon University
        !            45:  *  Pittsburgh PA 15213-3890
        !            46:  * 
        !            47:  * any improvements or extensions that they make and grant Carnegie Mellon
        !            48:  * the rights to redistribute these changes.
        !            49:  */
        !            50: /*
        !            51:  *     File:   clock_prim.c
        !            52:  *     Author: Avadis Tevanian, Jr.
        !            53:  *     Date:   1986
        !            54:  *
        !            55:  *     Clock primitives.
        !            56:  */
        !            57: #import <mach/features.h>
        !            58: 
        !            59: #include <mach/boolean.h>
        !            60: #include <mach/machine.h>
        !            61: #include <mach/time_value.h>
        !            62: #include <mach/vm_param.h>
        !            63: #include <mach/vm_prot.h>
        !            64: #include <kern/counters.h>
        !            65: #include <kern/cpu_number.h>
        !            66: #include <kern/clock.h>
        !            67: #include <kern/host.h>
        !            68: #include <kern/lock.h>
        !            69: #include <kern/mach_param.h>
        !            70: #include <kern/processor.h>
        !            71: #include <kern/sched.h>
        !            72: #include <kern/sched_prim.h>
        !            73: #include <kern/thread.h>
        !            74: #include <kern/time_out.h>
        !            75: #include <kern/time_stamp.h>
        !            76: #include <vm/vm_kern.h>
        !            77: #include <machine/mach_param.h>        /* HZ */
        !            78: #include <machine/machspl.h>
        !            79: 
        !            80: 
        !            81: 
        !            82: extern void    thread_quantum_update();
        !            83: 
        !            84: int            hz = HZ;                /* number of ticks per second */
        !            85: int            tick = (1000000 / HZ);  /* number of usec per tick */
        !            86: 
        !            87: tvalspec_t     tick_stamp;             /* timestamp of the last 'tick' */
        !            88: 
        !            89: /*
        !            90:  *     Handle clock interrupts.
        !            91:  *
        !            92:  *     The clock interrupt is assumed to be called at a (more or less)
        !            93:  *     constant rate.  The rate must be identical on all CPUS (XXX - fix).
        !            94:  *
        !            95:  *     Usec is the number of microseconds that have elapsed since the
        !            96:  *     last clock tick.  It may be constant or computed, depending on
        !            97:  *     the accuracy of the hardware clock.
        !            98:  *
        !            99:  */
        !           100: void clock_interrupt(usec, usermode, basepri)
        !           101:        register int    usec;           /* microseconds per tick */
        !           102:        boolean_t       usermode;       /* executing user code */
        !           103:        boolean_t       basepri;        /* at base priority */
        !           104: {
        !           105:        register int            my_cpu = cpu_number();
        !           106:        register thread_t       thread = current_thread();
        !           107: 
        !           108:        counter(c_clock_ticks++);
        !           109:        counter(c_threads_total += c_threads_current);
        !           110:        counter(c_stacks_total += c_stacks_current);
        !           111: 
        !           112: #if    STAT_TIME
        !           113:        /*
        !           114:         *      Increment the thread time, if using
        !           115:         *      statistical timing.
        !           116:         */
        !           117:        if (usermode) {
        !           118:            timer_bump(&thread->user_timer, usec);
        !           119:        }
        !           120:        else {
        !           121:            timer_bump(&thread->system_timer, usec);
        !           122:        }
        !           123: #endif STAT_TIME
        !           124: 
        !           125:        /*
        !           126:         *      Increment the CPU time statistics.
        !           127:         */
        !           128:        {
        !           129:            register int        state;
        !           130: 
        !           131:            if (usermode)
        !           132:                state = CPU_STATE_USER;
        !           133:            else if (!cpu_idle(my_cpu))
        !           134:                state = CPU_STATE_SYSTEM;
        !           135:            else
        !           136:                state = CPU_STATE_IDLE;
        !           137: 
        !           138:            machine_slot[my_cpu].cpu_ticks[state]++;
        !           139: 
        !           140:            /*
        !           141:             *  Adjust the thread's priority and check for
        !           142:             *  quantum expiration.
        !           143:             */
        !           144: 
        !           145:            if (!(thread->state & TH_IDLE))
        !           146:                thread_quantum_update(my_cpu, thread, 1, state);
        !           147:        }
        !           148: 
        !           149:        if (my_cpu == master_cpu) {
        !           150: 
        !           151:            /*
        !           152:             *  Perform scheduler housekeeping activities.
        !           153:             */
        !           154:            recompute_priorities();
        !           155: 
        !           156:            /*
        !           157:             *  Save a timestamp for this clock tick.  This
        !           158:             *  is used by set_timeout(), et al. to apply
        !           159:             *  appropriate rounding to timeout intervals.
        !           160:             *  This is really a hack which assumes that
        !           161:             *  'timer interrupts' have the same period and
        !           162:             *  phase as a clock tick.
        !           163:             */
        !           164:            tick_stamp = clock_get_counter(System);
        !           165: 
        !           166: #if    TS_FORMAT == 1
        !           167:            /*
        !           168:             *  Increment the tick count for the timestamping routine.
        !           169:             */
        !           170:            ts_tick_count++;
        !           171: #endif TS_FORMAT == 1
        !           172: 
        !           173:        }
        !           174: }
        !           175: 
        !           176: #if    SIMPLE_CLOCK
        !           177: 
        !           178: int
        !           179: sched_usec_elapsed(void)
        !           180: {
        !           181:        static tvalspec_t       sched_stamp;
        !           182:        tvalspec_t              delta_stamp,
        !           183:                                new_stamp = clock_get_counter(System);
        !           184:        int                     new_usec;
        !           185: 
        !           186:        delta_stamp = new_stamp;
        !           187:        SUB_TVALSPEC(&delta_stamp, &sched_stamp);
        !           188:        new_usec = (delta_stamp.tv_sec * USEC_PER_SEC) +
        !           189:                        (delta_stamp.tv_nsec / NSEC_PER_USEC);
        !           190:        sched_stamp = new_stamp;
        !           191:        
        !           192:        return (new_usec);
        !           193: }
        !           194: #endif /* SIMPLE_CLOCK */
        !           195: 
        !           196: tvalspec_t
        !           197: ticks_to_tvalspec(
        !           198:        unsigned int    ticks)
        !           199: {
        !           200:        tvalspec_t              result;
        !           201:     
        !           202:        result.tv_sec = ticks / TICKS_PER_SEC;
        !           203:        result.tv_nsec = (ticks % TICKS_PER_SEC) * NSEC_PER_TICK;
        !           204:     
        !           205:        return (result);
        !           206: }
        !           207: 
        !           208: decl_simple_lock_data(static,  timer_lock)     /* lock for ... */
        !           209: 
        !           210: static void
        !           211: service_timer(
        !           212:        timer_elt_t     telt)
        !           213: {
        !           214:        spl_t           s;
        !           215:        int             (*fcn)();
        !           216:        char            *param; 
        !           217:        
        !           218:        s = splsched();
        !           219:        simple_lock(&timer_lock);
        !           220:        
        !           221:        fcn = telt->fcn;
        !           222:        param = telt->param;
        !           223: 
        !           224:        telt->set = TELT_UNSET;
        !           225:        
        !           226:        simple_unlock(&timer_lock);
        !           227:        splx(s);
        !           228:        
        !           229:        (*fcn)(param);
        !           230: }
        !           231: 
        !           232: static __inline__ void
        !           233: init_timeout_element(
        !           234:        timer_elt_t     telt)
        !           235: {
        !           236:        telt->call.func = (thread_call_func_t)service_timer;
        !           237:        telt->call.spec_proto = telt;
        !           238:        telt->call.status = IDLE;
        !           239: }
        !           240: 
        !           241: /*
        !           242:  *     Set timeout.
        !           243:  *
        !           244:  *     Parameters:
        !           245:  *             telt     timer element.  Function and param are already set.
        !           246:  *             interval time-out interval, in hz.
        !           247:  */
        !           248: void set_timeout(telt, interval)
        !           249:        register timer_elt_t    telt;   /* already loaded */
        !           250:        register unsigned int   interval;
        !           251: {
        !           252:        spl_t           s;
        !           253:        tvalspec_t      deadline;
        !           254: 
        !           255:        s = splsched();
        !           256:        simple_lock(&timer_lock);
        !           257: 
        !           258:        if (telt->call.spec_proto != telt)
        !           259:            init_timeout_element(telt);
        !           260: 
        !           261:        deadline = ticks_to_tvalspec(interval);
        !           262:        ADD_TVALSPEC(&deadline, &tick_stamp);
        !           263:        
        !           264:        thread_call_enter_delayed(&telt->call, deadline);
        !           265: 
        !           266:        telt->set = TELT_SET;
        !           267: 
        !           268:        simple_unlock(&timer_lock);
        !           269:        splx(s);
        !           270: }
        !           271: 
        !           272: boolean_t reset_timeout(telt)
        !           273:        register timer_elt_t    telt;
        !           274: {
        !           275:        spl_t           s;
        !           276: 
        !           277:        s = splsched();
        !           278:        simple_lock(&timer_lock);
        !           279: 
        !           280:        if (telt->set) {
        !           281:            thread_call_cancel(&telt->call);
        !           282: 
        !           283:            telt->set = TELT_UNSET;
        !           284: 
        !           285:            simple_unlock(&timer_lock);
        !           286:            splx(s);
        !           287:            return TRUE;
        !           288:        }
        !           289:        else {
        !           290:            simple_unlock(&timer_lock);
        !           291:            splx(s);
        !           292:            return FALSE;
        !           293:        }
        !           294: }
        !           295: 
        !           296: void init_timeout()
        !           297: {
        !           298:        simple_lock_init(&timer_lock);
        !           299: }

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