1 /* $OpenBSD: kern_timeout.c,v 1.12 2001/12/22 16:41:51 nordin 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. Redistributions in binary form must reproduce the above copyright 14 * notice, this list of conditions and the following disclaimer in the 15 * documentation and/or other materials provided with the distribution. 16 * 3. The name of the author may not be used to endorse or promote products 17 * derived from this software without specific prior written permission. 18 * 19 * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, 20 * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY 21 * AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL 22 * THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, 23 * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, 24 * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; 25 * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, 26 * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR 27 * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF 28 * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. 29 */ 30 31 #include <sys/param.h> 32 #include <sys/systm.h> 33 #include <sys/lock.h> 34 #include <sys/timeout.h> 35 36 #ifdef DDB 37 #include <machine/db_machdep.h> 38 #include <ddb/db_interface.h> 39 #include <ddb/db_access.h> 40 #include <ddb/db_sym.h> 41 #include <ddb/db_output.h> 42 #endif 43 44 /* 45 * Timeouts are kept in a hierarchical timing wheel. The to_time is the value 46 * of the global variable "ticks" when the timeout should be called. There are 47 * four levels with 256 buckets each. See 'Scheme 7' in 48 * "Hashed and Hierarchical Timing Wheels: Efficient Data Structures for 49 * Implementing a Timer Facility" by George Varghese and Tony Lauck. 50 */ 51 #define BUCKETS 1024 52 #define WHEELSIZE 256 53 #define WHEELMASK 255 54 #define WHEELBITS 8 55 56 struct circq timeout_wheel[BUCKETS]; /* Queues of timeouts */ 57 struct circq timeout_todo; /* Worklist */ 58 59 #define MASKWHEEL(wheel, time) (((time) >> ((wheel)*WHEELBITS)) & WHEELMASK) 60 61 #define BUCKET(rel, abs) \ 62 (((rel) <= (1 << (2*WHEELBITS))) \ 63 ? ((rel) <= (1 << WHEELBITS)) \ 64 ? timeout_wheel[MASKWHEEL(0, (abs))] \ 65 : timeout_wheel[MASKWHEEL(1, (abs)) + WHEELSIZE] \ 66 : ((rel) <= (1 << (3*WHEELBITS))) \ 67 ? timeout_wheel[MASKWHEEL(2, (abs)) + 2*WHEELSIZE] \ 68 : timeout_wheel[MASKWHEEL(3, (abs)) + 3*WHEELSIZE]) 69 70 #define MOVEBUCKET(wheel, time) \ 71 CIRCQ_APPEND(&timeout_todo, \ 72 &timeout_wheel[MASKWHEEL((wheel), (time)) + (wheel)*WHEELSIZE]) 73 74 /* 75 * All wheels are locked with the same lock (which must also block out all 76 * interrupts). 77 */ 78 struct simplelock _timeout_lock; 79 80 #define timeout_wheel_lock(s) \ 81 do { *(s) = splhigh(); simple_lock(&_timeout_lock); } while (0) 82 #define timeout_wheel_unlock(s) \ 83 do { simple_unlock(&_timeout_lock); splx(s); } while (0) 84 85 /* 86 * Circular queue definitions. 87 */ 88 89 #define CIRCQ_INIT(elem) do { \ 90 (elem)->next = (elem); \ 91 (elem)->prev = (elem); \ 92 } while (0) 93 94 #define CIRCQ_INSERT(elem, list) do { \ 95 (elem)->prev = (list)->prev; \ 96 (elem)->next = (list); \ 97 (list)->prev->next = (elem); \ 98 (list)->prev = (elem); \ 99 } while (0) 100 101 #define CIRCQ_APPEND(fst, snd) do { \ 102 if (!CIRCQ_EMPTY(snd)) { \ 103 (fst)->prev->next = (snd)->next;\ 104 (snd)->next->prev = (fst)->prev;\ 105 (snd)->prev->next = (fst); \ 106 (fst)->prev = (snd)->prev; \ 107 CIRCQ_INIT(snd); \ 108 } \ 109 } while (0) 110 111 #define CIRCQ_REMOVE(elem) do { \ 112 (elem)->next->prev = (elem)->prev; \ 113 (elem)->prev->next = (elem)->next; \ 114 } while (0) 115 116 #define CIRCQ_FIRST(elem) ((elem)->next) 117 118 #define CIRCQ_EMPTY(elem) (CIRCQ_FIRST(elem) == (elem)) 119 120 /* 121 * Some of the "math" in here is a bit tricky. 122 * 123 * We have to beware of wrapping ints. 124 * We use the fact that any element added to the queue must be added with a 125 * positive time. That means that any element `to' on the queue cannot be 126 * scheduled to timeout further in time than INT_MAX, but to->to_time can 127 * be positive or negative so comparing it with anything is dangerous. 128 * The only way we can use the to->to_time value in any predictable way 129 * is when we caluculate how far in the future `to' will timeout - 130 * "to->to_time - ticks". The result will always be positive for future 131 * timeouts and 0 or negative for due timeouts. 132 */ 133 extern int ticks; /* XXX - move to sys/X.h */ 134 135 void 136 timeout_startup(void) 137 { 138 int b; 139 140 CIRCQ_INIT(&timeout_todo); 141 for (b = 0; b < BUCKETS; b++) 142 CIRCQ_INIT(&timeout_wheel[b]); 143 simple_lock_init(&_timeout_lock); 144 } 145 146 void 147 timeout_set(struct timeout *new, void (*fn)(void *), void *arg) 148 { 149 new->to_func = fn; 150 new->to_arg = arg; 151 new->to_flags = TIMEOUT_INITIALIZED; 152 } 153 154 155 void 156 timeout_add(struct timeout *new, int to_ticks) 157 { 158 int s; 159 160 timeout_wheel_lock(&s); 161 #ifdef DIAGNOSTIC 162 if (!(new->to_flags & TIMEOUT_INITIALIZED)) 163 panic("timeout_add: not initialized"); 164 if (to_ticks < 0) 165 panic("timeout_add: to_ticks < 0"); 166 #endif 167 /* If this timeout was already on a queue we remove it. */ 168 if (new->to_flags & TIMEOUT_ONQUEUE) 169 CIRCQ_REMOVE(&new->to_list); 170 else 171 new->to_flags |= TIMEOUT_ONQUEUE; 172 173 /* Initialize the time here, it won't change. */ 174 new->to_time = to_ticks + ticks; 175 new->to_flags &= ~TIMEOUT_TRIGGERED; 176 177 CIRCQ_INSERT(&new->to_list, &timeout_todo); 178 timeout_wheel_unlock(s); 179 } 180 181 void 182 timeout_del(struct timeout *to) 183 { 184 int s; 185 186 timeout_wheel_lock(&s); 187 if (to->to_flags & TIMEOUT_ONQUEUE) { 188 CIRCQ_REMOVE(&to->to_list); 189 to->to_flags &= ~TIMEOUT_ONQUEUE; 190 } 191 to->to_flags &= ~TIMEOUT_TRIGGERED; 192 timeout_wheel_unlock(s); 193 } 194 195 /* 196 * This is called from hardclock() once every tick. 197 * We return !0 if we need to schedule a softclock. 198 * 199 * We don't need locking in here. 200 */ 201 int 202 timeout_hardclock_update(void) 203 { 204 MOVEBUCKET(0, ticks); 205 if (MASKWHEEL(0, ticks) == 0) { 206 MOVEBUCKET(1, ticks); 207 if (MASKWHEEL(1, ticks) == 0) { 208 MOVEBUCKET(2, ticks); 209 if (MASKWHEEL(2, ticks) == 0) 210 MOVEBUCKET(3, ticks); 211 } 212 } 213 return (!CIRCQ_EMPTY(&timeout_todo)); 214 } 215 216 void 217 softclock(void) 218 { 219 struct timeout *to; 220 int s; 221 void (*fn)(void *); 222 void *arg; 223 224 timeout_wheel_lock(&s); 225 while (!CIRCQ_EMPTY(&timeout_todo)) { 226 227 to = (struct timeout *)CIRCQ_FIRST(&timeout_todo); /* XXX */ 228 CIRCQ_REMOVE(&to->to_list); 229 230 /* If due run it, otherwise insert it into the right bucket. */ 231 if (to->to_time - ticks > 0) { 232 CIRCQ_INSERT(&to->to_list, 233 &BUCKET((to->to_time - ticks), to->to_time)); 234 } else { 235 #ifdef DEBUG 236 if (to->to_time - ticks < 0) 237 printf("timeout delayed %d\n", to->to_time - 238 ticks); 239 #endif 240 to->to_flags &= ~TIMEOUT_ONQUEUE; 241 to->to_flags |= TIMEOUT_TRIGGERED; 242 243 fn = to->to_func; 244 arg = to->to_arg; 245 246 timeout_wheel_unlock(s); 247 fn(arg); 248 timeout_wheel_lock(&s); 249 } 250 } 251 timeout_wheel_unlock(s); 252 } 253 254 #ifdef DDB 255 void db_show_callout_bucket __P((struct circq *)); 256 257 void 258 db_show_callout_bucket(struct circq *bucket) 259 { 260 struct timeout *to; 261 struct circq *p; 262 db_expr_t offset; 263 char *name; 264 265 for (p = CIRCQ_FIRST(bucket); p != bucket; p = CIRCQ_FIRST(p)) { 266 to = (struct timeout *)p; /* XXX */ 267 db_find_sym_and_offset((db_addr_t)to->to_func, &name, &offset); 268 name = name ? name : "?"; 269 db_printf("%9d %2d/%-4d %8x %s\n", to->to_time - ticks, 270 (bucket - timeout_wheel) / WHEELSIZE, 271 bucket - timeout_wheel, to->to_arg, name); 272 } 273 } 274 275 void 276 db_show_callout(db_expr_t addr, int haddr, db_expr_t count, char *modif) 277 { 278 int s; 279 int b; 280 281 db_printf("ticks now: %d\n", ticks); 282 db_printf(" ticks wheel arg func\n"); 283 284 timeout_wheel_lock(&s); 285 286 /* XXX: Show timeout_todo? */ 287 for (b = 0; b < BUCKETS; b++) 288 db_show_callout_bucket(&timeout_wheel[b]); 289 290 timeout_wheel_unlock(s); 291 } 292 #endif 293