1 /* $OpenBSD: kern_timeout.c,v 1.18 2003/06/03 12:05:25 art Exp $ */ 2 /* 3 * Copyright (c) 2001 Thomas Nordin <nordin@openbsd.org> 4 * Copyright (c) 2000-2001 Artur Grabowski <art@openbsd.org> 5 * All rights reserved. 6 * 7 * Redistribution and use in source and binary forms, with or without 8 * modification, are permitted provided that the following conditions 9 * are met: 10 * 11 * 1. Redistributions of source code must retain the above copyright 12 * notice, this list of conditions and the following disclaimer. 13 * 2. The name of the author may not be used to endorse or promote products 14 * derived from this software without specific prior written permission. 15 * 16 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, 17 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY 18 * AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL 19 * THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, 20 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, 21 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; 22 * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, 23 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR 24 * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF 25 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 26 */ 27 28 #include <sys/param.h> 29 #include <sys/systm.h> 30 #include <sys/lock.h> 31 #include <sys/timeout.h> 32 33 #ifdef DDB 34 #include <machine/db_machdep.h> 35 #include <ddb/db_interface.h> 36 #include <ddb/db_access.h> 37 #include <ddb/db_sym.h> 38 #include <ddb/db_output.h> 39 #endif 40 41 /* 42 * Timeouts are kept in a hierarchical timing wheel. The to_time is the value 43 * of the global variable "ticks" when the timeout should be called. There are 44 * four levels with 256 buckets each. See 'Scheme 7' in 45 * "Hashed and Hierarchical Timing Wheels: Efficient Data Structures for 46 * Implementing a Timer Facility" by George Varghese and Tony Lauck. 47 */ 48 #define BUCKETS 1024 49 #define WHEELSIZE 256 50 #define WHEELMASK 255 51 #define WHEELBITS 8 52 53 struct circq timeout_wheel[BUCKETS]; /* Queues of timeouts */ 54 struct circq timeout_todo; /* Worklist */ 55 56 #define MASKWHEEL(wheel, time) (((time) >> ((wheel)*WHEELBITS)) & WHEELMASK) 57 58 #define BUCKET(rel, abs) \ 59 (((rel) <= (1 << (2*WHEELBITS))) \ 60 ? ((rel) <= (1 << WHEELBITS)) \ 61 ? timeout_wheel[MASKWHEEL(0, (abs))] \ 62 : timeout_wheel[MASKWHEEL(1, (abs)) + WHEELSIZE] \ 63 : ((rel) <= (1 << (3*WHEELBITS))) \ 64 ? timeout_wheel[MASKWHEEL(2, (abs)) + 2*WHEELSIZE] \ 65 : timeout_wheel[MASKWHEEL(3, (abs)) + 3*WHEELSIZE]) 66 67 #define MOVEBUCKET(wheel, time) \ 68 CIRCQ_APPEND(&timeout_todo, \ 69 &timeout_wheel[MASKWHEEL((wheel), (time)) + (wheel)*WHEELSIZE]) 70 71 /* 72 * All wheels are locked with the same lock (which must also block out all 73 * interrupts). 74 */ 75 struct simplelock _timeout_lock; 76 77 #define timeout_wheel_lock(s) \ 78 do { *(s) = splhigh(); simple_lock(&_timeout_lock); } while (0) 79 #define timeout_wheel_unlock(s) \ 80 do { simple_unlock(&_timeout_lock); splx(s); } while (0) 81 82 /* 83 * Circular queue definitions. 84 */ 85 86 #define CIRCQ_INIT(elem) do { \ 87 (elem)->next = (elem); \ 88 (elem)->prev = (elem); \ 89 } while (0) 90 91 #define CIRCQ_INSERT(elem, list) do { \ 92 (elem)->prev = (list)->prev; \ 93 (elem)->next = (list); \ 94 (list)->prev->next = (elem); \ 95 (list)->prev = (elem); \ 96 } while (0) 97 98 #define CIRCQ_APPEND(fst, snd) do { \ 99 if (!CIRCQ_EMPTY(snd)) { \ 100 (fst)->prev->next = (snd)->next;\ 101 (snd)->next->prev = (fst)->prev;\ 102 (snd)->prev->next = (fst); \ 103 (fst)->prev = (snd)->prev; \ 104 CIRCQ_INIT(snd); \ 105 } \ 106 } while (0) 107 108 #define CIRCQ_REMOVE(elem) do { \ 109 (elem)->next->prev = (elem)->prev; \ 110 (elem)->prev->next = (elem)->next; \ 111 } while (0) 112 113 #define CIRCQ_FIRST(elem) ((elem)->next) 114 115 #define CIRCQ_EMPTY(elem) (CIRCQ_FIRST(elem) == (elem)) 116 117 /* 118 * Some of the "math" in here is a bit tricky. 119 * 120 * We have to beware of wrapping ints. 121 * We use the fact that any element added to the queue must be added with a 122 * positive time. That means that any element `to' on the queue cannot be 123 * scheduled to timeout further in time than INT_MAX, but to->to_time can 124 * be positive or negative so comparing it with anything is dangerous. 125 * The only way we can use the to->to_time value in any predictable way 126 * is when we calculate how far in the future `to' will timeout - 127 * "to->to_time - ticks". The result will always be positive for future 128 * timeouts and 0 or negative for due timeouts. 129 */ 130 extern int ticks; /* XXX - move to sys/X.h */ 131 132 void 133 timeout_startup(void) 134 { 135 int b; 136 137 CIRCQ_INIT(&timeout_todo); 138 for (b = 0; b < BUCKETS; b++) 139 CIRCQ_INIT(&timeout_wheel[b]); 140 simple_lock_init(&_timeout_lock); 141 } 142 143 void 144 timeout_set(struct timeout *new, void (*fn)(void *), void *arg) 145 { 146 new->to_func = fn; 147 new->to_arg = arg; 148 new->to_flags = TIMEOUT_INITIALIZED; 149 } 150 151 152 void 153 timeout_add(struct timeout *new, int to_ticks) 154 { 155 int s; 156 int old_time; 157 158 #ifdef DIAGNOSTIC 159 if (!(new->to_flags & TIMEOUT_INITIALIZED)) 160 panic("timeout_add: not initialized"); 161 if (to_ticks < 0) 162 panic("timeout_add: to_ticks < 0"); 163 #endif 164 165 timeout_wheel_lock(&s); 166 /* Initialize the time here, it won't change. */ 167 old_time = new->to_time; 168 new->to_time = to_ticks + ticks; 169 new->to_flags &= ~TIMEOUT_TRIGGERED; 170 171 /* 172 * If this timeout already is scheduled and now is moved 173 * earlier, reschedule it now. Otherwise leave it in place 174 * and let it be rescheduled later. 175 */ 176 if (new->to_flags & TIMEOUT_ONQUEUE) { 177 if (new->to_time - ticks < old_time - ticks) { 178 CIRCQ_REMOVE(&new->to_list); 179 CIRCQ_INSERT(&new->to_list, &timeout_todo); 180 } 181 } else { 182 new->to_flags |= TIMEOUT_ONQUEUE; 183 CIRCQ_INSERT(&new->to_list, &timeout_todo); 184 } 185 186 timeout_wheel_unlock(s); 187 } 188 189 void 190 timeout_del(struct timeout *to) 191 { 192 int s; 193 194 timeout_wheel_lock(&s); 195 if (to->to_flags & TIMEOUT_ONQUEUE) { 196 CIRCQ_REMOVE(&to->to_list); 197 to->to_flags &= ~TIMEOUT_ONQUEUE; 198 } 199 to->to_flags &= ~TIMEOUT_TRIGGERED; 200 timeout_wheel_unlock(s); 201 } 202 203 /* 204 * This is called from hardclock() once every tick. 205 * We return !0 if we need to schedule a softclock. 206 * 207 * We don't need locking in here. 208 */ 209 int 210 timeout_hardclock_update(void) 211 { 212 MOVEBUCKET(0, ticks); 213 if (MASKWHEEL(0, ticks) == 0) { 214 MOVEBUCKET(1, ticks); 215 if (MASKWHEEL(1, ticks) == 0) { 216 MOVEBUCKET(2, ticks); 217 if (MASKWHEEL(2, ticks) == 0) 218 MOVEBUCKET(3, ticks); 219 } 220 } 221 return (!CIRCQ_EMPTY(&timeout_todo)); 222 } 223 224 void 225 softclock(void) 226 { 227 struct timeout *to; 228 int s; 229 void (*fn)(void *); 230 void *arg; 231 232 timeout_wheel_lock(&s); 233 while (!CIRCQ_EMPTY(&timeout_todo)) { 234 235 to = (struct timeout *)CIRCQ_FIRST(&timeout_todo); /* XXX */ 236 CIRCQ_REMOVE(&to->to_list); 237 238 /* If due run it, otherwise insert it into the right bucket. */ 239 if (to->to_time - ticks > 0) { 240 CIRCQ_INSERT(&to->to_list, 241 &BUCKET((to->to_time - ticks), to->to_time)); 242 } else { 243 #ifdef DEBUG 244 if (to->to_time - ticks < 0) 245 printf("timeout delayed %d\n", to->to_time - 246 ticks); 247 #endif 248 to->to_flags &= ~TIMEOUT_ONQUEUE; 249 to->to_flags |= TIMEOUT_TRIGGERED; 250 251 fn = to->to_func; 252 arg = to->to_arg; 253 254 timeout_wheel_unlock(s); 255 fn(arg); 256 timeout_wheel_lock(&s); 257 } 258 } 259 timeout_wheel_unlock(s); 260 } 261 262 #ifdef DDB 263 void db_show_callout_bucket(struct circq *); 264 265 void 266 db_show_callout_bucket(struct circq *bucket) 267 { 268 struct timeout *to; 269 struct circq *p; 270 db_expr_t offset; 271 char *name; 272 273 for (p = CIRCQ_FIRST(bucket); p != bucket; p = CIRCQ_FIRST(p)) { 274 to = (struct timeout *)p; /* XXX */ 275 db_find_sym_and_offset((db_addr_t)to->to_func, &name, &offset); 276 name = name ? name : "?"; 277 db_printf("%9d %2d/%-4d %8x %s\n", to->to_time - ticks, 278 (bucket - timeout_wheel) / WHEELSIZE, 279 bucket - timeout_wheel, to->to_arg, name); 280 } 281 } 282 283 void 284 db_show_callout(db_expr_t addr, int haddr, db_expr_t count, char *modif) 285 { 286 int s; 287 int b; 288 289 db_printf("ticks now: %d\n", ticks); 290 db_printf(" ticks wheel arg func\n"); 291 292 timeout_wheel_lock(&s); 293 294 db_show_callout_bucket(&timeout_todo); 295 for (b = 0; b < BUCKETS; b++) 296 db_show_callout_bucket(&timeout_wheel[b]); 297 298 timeout_wheel_unlock(s); 299 } 300 #endif 301