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| 1 | jermar | 1 | /* |
| 2 | * Copyright (C) 2001-2004 Jakub Jermar |
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| 3 | * All rights reserved. |
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| 4 | * |
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| 5 | * Redistribution and use in source and binary forms, with or without |
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| 6 | * modification, are permitted provided that the following conditions |
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| 7 | * are met: |
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| 8 | * |
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| 9 | * - Redistributions of source code must retain the above copyright |
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| 10 | * notice, this list of conditions and the following disclaimer. |
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| 11 | * - Redistributions in binary form must reproduce the above copyright |
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| 12 | * notice, this list of conditions and the following disclaimer in the |
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| 13 | * documentation and/or other materials provided with the distribution. |
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| 14 | * - The name of the author may not be used to endorse or promote products |
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| 15 | * derived from this software without specific prior written permission. |
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| 16 | * |
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| 17 | * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR |
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| 18 | * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES |
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| 19 | * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. |
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| 20 | * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, |
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| 21 | * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT |
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| 22 | * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, |
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| 23 | * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY |
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| 24 | * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT |
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| 25 | * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF |
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| 26 | * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. |
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| 27 | */ |
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| 28 | |||
| 1264 | jermar | 29 | /** |
| 30 | * @file clock.c |
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| 31 | * @brief High-level clock interrupt handler. |
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| 32 | * |
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| 33 | * This file contains the clock() function which is the source |
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| 34 | * of preemption. It is also responsible for executing expired |
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| 35 | * timeouts. |
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| 36 | */ |
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| 37 | |||
| 1 | jermar | 38 | #include <time/clock.h> |
| 39 | #include <time/timeout.h> |
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| 40 | #include <arch/types.h> |
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| 41 | #include <config.h> |
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| 42 | #include <synch/spinlock.h> |
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| 43 | #include <synch/waitq.h> |
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| 44 | #include <func.h> |
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| 45 | #include <proc/scheduler.h> |
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| 46 | #include <cpu.h> |
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| 47 | #include <arch.h> |
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| 788 | jermar | 48 | #include <adt/list.h> |
| 1104 | jermar | 49 | #include <atomic.h> |
| 391 | jermar | 50 | #include <proc/thread.h> |
| 1434 | palkovsky | 51 | #include <sysinfo/sysinfo.h> |
| 52 | #include <arch/barrier.h> |
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| 1 | jermar | 53 | |
| 1434 | palkovsky | 54 | /* Pointers to public variables with time */ |
| 55 | struct ptime { |
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| 1438 | palkovsky | 56 | __native seconds1; |
| 1434 | palkovsky | 57 | __native useconds; |
| 1438 | palkovsky | 58 | __native seconds2; |
| 1434 | palkovsky | 59 | }; |
| 60 | struct ptime *public_time; |
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| 61 | /* Variable holding fragment of second, so that we would update |
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| 62 | * seconds correctly |
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| 63 | */ |
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| 64 | static __native secfrag = 0; |
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| 65 | |||
| 66 | /** Initialize realtime clock counter |
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| 67 | * |
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| 68 | * The applications (and sometimes kernel) need to access accurate |
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| 69 | * information about realtime data. We allocate 1 page with these |
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| 70 | * data and update it periodically. |
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| 71 | * |
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| 72 | * |
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| 73 | */ |
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| 74 | void clock_counter_init(void) |
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| 75 | { |
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| 76 | void *faddr; |
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| 77 | |||
| 78 | faddr = (void *)PFN2ADDR(frame_alloc(0, FRAME_ATOMIC)); |
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| 79 | if (!faddr) |
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| 80 | panic("Cannot allocate page for clock"); |
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| 81 | |||
| 82 | public_time = (struct ptime *)PA2KA(faddr); |
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| 83 | |||
| 84 | /* TODO: We would need some arch dependent settings here */ |
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| 1438 | palkovsky | 85 | public_time->seconds1 = 0; |
| 86 | public_time->seconds2 = 0; |
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| 1434 | palkovsky | 87 | public_time->useconds = 0; |
| 88 | |||
| 89 | sysinfo_set_item_val("clock.faddr", NULL, (__native)faddr); |
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| 90 | } |
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| 91 | |||
| 92 | |||
| 93 | /** Update public counters |
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| 94 | * |
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| 95 | * Update it only on first processor |
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| 96 | * TODO: Do we really need so many write barriers? |
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| 97 | */ |
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| 98 | static void clock_update_counters(void) |
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| 99 | { |
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| 100 | if (CPU->id == 0) { |
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| 101 | secfrag += 1000000/HZ; |
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| 102 | if (secfrag >= 1000000) { |
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| 1438 | palkovsky | 103 | secfrag -= 1000000; |
| 104 | public_time->seconds1++; |
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| 1434 | palkovsky | 105 | write_barrier(); |
| 1438 | palkovsky | 106 | public_time->useconds = secfrag; |
| 107 | write_barrier(); |
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| 108 | public_time->seconds2 = public_time->seconds1; |
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| 1434 | palkovsky | 109 | } else |
| 110 | public_time->useconds += 1000000/HZ; |
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| 111 | } |
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| 112 | } |
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| 113 | |||
| 107 | decky | 114 | /** Clock routine |
| 115 | * |
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| 116 | * Clock routine executed from clock interrupt handler |
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| 413 | jermar | 117 | * (assuming interrupts_disable()'d). Runs expired timeouts |
| 107 | decky | 118 | * and preemptive scheduling. |
| 119 | * |
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| 1 | jermar | 120 | */ |
| 121 | void clock(void) |
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| 122 | { |
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| 123 | link_t *l; |
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| 124 | timeout_t *h; |
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| 411 | jermar | 125 | timeout_handler_t f; |
| 1 | jermar | 126 | void *arg; |
| 1457 | jermar | 127 | count_t missed_clock_ticks = CPU->missed_clock_ticks; |
| 1431 | jermar | 128 | int i; |
| 1 | jermar | 129 | |
| 130 | /* |
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| 131 | * To avoid lock ordering problems, |
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| 132 | * run all expired timeouts as you visit them. |
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| 133 | */ |
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| 1457 | jermar | 134 | for (i = 0; i <= missed_clock_ticks; i++) { |
| 1434 | palkovsky | 135 | clock_update_counters(); |
| 1431 | jermar | 136 | spinlock_lock(&CPU->timeoutlock); |
| 137 | while ((l = CPU->timeout_active_head.next) != &CPU->timeout_active_head) { |
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| 138 | h = list_get_instance(l, timeout_t, link); |
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| 139 | spinlock_lock(&h->lock); |
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| 140 | if (h->ticks-- != 0) { |
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| 141 | spinlock_unlock(&h->lock); |
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| 142 | break; |
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| 143 | } |
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| 144 | list_remove(l); |
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| 145 | f = h->handler; |
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| 146 | arg = h->arg; |
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| 147 | timeout_reinitialize(h); |
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| 148 | spinlock_unlock(&h->lock); |
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| 149 | spinlock_unlock(&CPU->timeoutlock); |
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| 150 | |||
| 151 | f(arg); |
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| 152 | |||
| 153 | spinlock_lock(&CPU->timeoutlock); |
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| 1 | jermar | 154 | } |
| 15 | jermar | 155 | spinlock_unlock(&CPU->timeoutlock); |
| 1 | jermar | 156 | } |
| 1431 | jermar | 157 | CPU->missed_clock_ticks = 0; |
| 1 | jermar | 158 | |
| 159 | /* |
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| 15 | jermar | 160 | * Do CPU usage accounting and find out whether to preempt THREAD. |
| 1 | jermar | 161 | */ |
| 162 | |||
| 15 | jermar | 163 | if (THREAD) { |
| 221 | jermar | 164 | __u64 ticks; |
| 165 | |||
| 15 | jermar | 166 | spinlock_lock(&CPU->lock); |
| 1457 | jermar | 167 | CPU->needs_relink += 1 + missed_clock_ticks; |
| 15 | jermar | 168 | spinlock_unlock(&CPU->lock); |
| 1 | jermar | 169 | |
| 15 | jermar | 170 | spinlock_lock(&THREAD->lock); |
| 1457 | jermar | 171 | if ((ticks = THREAD->ticks)) { |
| 172 | if (ticks >= 1 + missed_clock_ticks) |
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| 173 | THREAD->ticks -= 1 + missed_clock_ticks; |
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| 174 | else |
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| 175 | THREAD->ticks = 0; |
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| 176 | } |
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| 221 | jermar | 177 | spinlock_unlock(&THREAD->lock); |
| 178 | |||
| 179 | if (!ticks && !PREEMPTION_DISABLED) { |
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| 1 | jermar | 180 | scheduler(); |
| 181 | } |
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| 182 | } |
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| 183 | |||
| 184 | } |