/* $NetBSD: kern_timeout.c,v 1.17 2005/12/11 12:24:29 christos Exp $ */ /*- * Copyright (c) 2003 The NetBSD Foundation, Inc. * All rights reserved. * * This code is derived from software contributed to The NetBSD Foundation * by Jason R. Thorpe. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. All advertising materials mentioning features or use of this software * must display the following acknowledgement: * This product includes software developed by the NetBSD * Foundation, Inc. and its contributors. * 4. Neither the name of The NetBSD Foundation nor the names of its * contributors may be used to endorse or promote products derived * from this software without specific prior written permission. * * THIS SOFTWARE IS PROVIDED BY THE NETBSD FOUNDATION, INC. AND CONTRIBUTORS * ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED * TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR * PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE FOUNDATION OR CONTRIBUTORS * BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE * POSSIBILITY OF SUCH DAMAGE. */ /* * Copyright (c) 2001 Thomas Nordin * Copyright (c) 2000-2001 Artur Grabowski * All rights reserved. * * Redistribution and use in source and binary forms, with or without * modification, are permitted provided that the following conditions * are met: * * 1. Redistributions of source code must retain the above copyright * notice, this list of conditions and the following disclaimer. * 2. Redistributions in binary form must reproduce the above copyright * notice, this list of conditions and the following disclaimer in the * documentation and/or other materials provided with the distribution. * 3. The name of the author may not be used to endorse or promote products * derived from this software without specific prior written permission. * * THIS SOFTWARE IS PROVIDED ``AS IS'' AND ANY EXPRESS OR IMPLIED WARRANTIES, * INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTABILITY * AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL * THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, * EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, * PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; * OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, * WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR * OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF * ADVISED OF THE POSSIBILITY OF SUCH DAMAGE. */ #include __KERNEL_RCSID(0, "$NetBSD: kern_timeout.c,v 1.17 2005/12/11 12:24:29 christos Exp $"); /* * Adapted from OpenBSD: kern_timeout.c,v 1.15 2002/12/08 04:21:07 art Exp, * modified to match NetBSD's pre-existing callout API. */ #include #include #include #include #include #ifdef DDB #include #include #include #include #include #endif /* * Timeouts are kept in a hierarchical timing wheel. The c_time is the value * of the global variable "hardclock_ticks" when the timeout should be called. * There are four levels with 256 buckets each. See 'Scheme 7' in * "Hashed and Hierarchical Timing Wheels: Efficient Data Structures for * Implementing a Timer Facility" by George Varghese and Tony Lauck. */ #define BUCKETS 1024 #define WHEELSIZE 256 #define WHEELMASK 255 #define WHEELBITS 8 static struct callout_circq timeout_wheel[BUCKETS]; /* Queues of timeouts */ static struct callout_circq timeout_todo; /* Worklist */ #define MASKWHEEL(wheel, time) (((time) >> ((wheel)*WHEELBITS)) & WHEELMASK) #define BUCKET(rel, abs) \ (((rel) <= (1 << (2*WHEELBITS))) \ ? ((rel) <= (1 << WHEELBITS)) \ ? &timeout_wheel[MASKWHEEL(0, (abs))] \ : &timeout_wheel[MASKWHEEL(1, (abs)) + WHEELSIZE] \ : ((rel) <= (1 << (3*WHEELBITS))) \ ? &timeout_wheel[MASKWHEEL(2, (abs)) + 2*WHEELSIZE] \ : &timeout_wheel[MASKWHEEL(3, (abs)) + 3*WHEELSIZE]) #define MOVEBUCKET(wheel, time) \ CIRCQ_APPEND(&timeout_todo, \ &timeout_wheel[MASKWHEEL((wheel), (time)) + (wheel)*WHEELSIZE]) /* * All wheels are locked with the same lock (which must also block out all * interrupts). */ static struct simplelock callout_slock; #define CALLOUT_LOCK(s) \ do { \ s = splsched(); \ simple_lock(&callout_slock); \ } while (/*CONSTCOND*/0) #define CALLOUT_UNLOCK(s) \ do { \ simple_unlock(&callout_slock); \ splx((s)); \ } while (/*CONSTCOND*/0) /* * Circular queue definitions. */ #define CIRCQ_INIT(list) \ do { \ (list)->cq_next_l = (list); \ (list)->cq_prev_l = (list); \ } while (/*CONSTCOND*/0) #define CIRCQ_INSERT(elem, list) \ do { \ (elem)->cq_prev_e = (list)->cq_prev_e; \ (elem)->cq_next_l = (list); \ (list)->cq_prev_l->cq_next_l = (elem); \ (list)->cq_prev_l = (elem); \ } while (/*CONSTCOND*/0) #define CIRCQ_APPEND(fst, snd) \ do { \ if (!CIRCQ_EMPTY(snd)) { \ (fst)->cq_prev_l->cq_next_l = (snd)->cq_next_l; \ (snd)->cq_next_l->cq_prev_l = (fst)->cq_prev_l; \ (snd)->cq_prev_l->cq_next_l = (fst); \ (fst)->cq_prev_l = (snd)->cq_prev_l; \ CIRCQ_INIT(snd); \ } \ } while (/*CONSTCOND*/0) #define CIRCQ_REMOVE(elem) \ do { \ (elem)->cq_next_l->cq_prev_e = (elem)->cq_prev_e; \ (elem)->cq_prev_l->cq_next_e = (elem)->cq_next_e; \ } while (/*CONSTCOND*/0) #define CIRCQ_FIRST(list) ((list)->cq_next_e) #define CIRCQ_NEXT(elem) ((elem)->cq_next_e) #define CIRCQ_LAST(elem,list) ((elem)->cq_next_l == (list)) #define CIRCQ_EMPTY(list) ((list)->cq_next_l == (list)) /* * Some of the "math" in here is a bit tricky. * * We have to beware of wrapping ints. * We use the fact that any element added to the queue must be added with a * positive time. That means that any element `to' on the queue cannot be * scheduled to timeout further in time than INT_MAX, but c->c_time can * be positive or negative so comparing it with anything is dangerous. * The only way we can use the c->c_time value in any predictable way * is when we calculate how far in the future `to' will timeout - * "c->c_time - hardclock_ticks". The result will always be positive for * future timeouts and 0 or negative for due timeouts. */ #ifdef CALLOUT_EVENT_COUNTERS static struct evcnt callout_ev_late; #endif /* * callout_startup: * * Initialize the callout facility, called at system startup time. */ void callout_startup(void) { int b; CIRCQ_INIT(&timeout_todo); for (b = 0; b < BUCKETS; b++) CIRCQ_INIT(&timeout_wheel[b]); simple_lock_init(&callout_slock); #ifdef CALLOUT_EVENT_COUNTERS evcnt_attach_dynamic(&callout_ev_late, EVCNT_TYPE_MISC, NULL, "callout", "late"); #endif } /* * callout_init: * * Initialize a callout structure. */ void callout_init(struct callout *c) { memset(c, 0, sizeof(*c)); } /* * callout_reset: * * Reset a callout structure with a new function and argument, and * schedule it to run. */ void callout_reset(struct callout *c, int to_ticks, void (*func)(void *), void *arg) { int s, old_time; KASSERT(to_ticks >= 0); CALLOUT_LOCK(s); /* Initialize the time here, it won't change. */ old_time = c->c_time; c->c_time = to_ticks + hardclock_ticks; c->c_flags &= ~(CALLOUT_FIRED|CALLOUT_INVOKING); c->c_func = func; c->c_arg = arg; /* * If this timeout is already scheduled and now is moved * earlier, reschedule it now. Otherwise leave it in place * and let it be rescheduled later. */ if (callout_pending(c)) { if (c->c_time - old_time < 0) { CIRCQ_REMOVE(&c->c_list); CIRCQ_INSERT(&c->c_list, &timeout_todo); } } else { c->c_flags |= CALLOUT_PENDING; CIRCQ_INSERT(&c->c_list, &timeout_todo); } CALLOUT_UNLOCK(s); } /* * callout_schedule: * * Schedule a callout to run. The function and argument must * already be set in the callout structure. */ void callout_schedule(struct callout *c, int to_ticks) { int s, old_time; KASSERT(to_ticks >= 0); CALLOUT_LOCK(s); /* Initialize the time here, it won't change. */ old_time = c->c_time; c->c_time = to_ticks + hardclock_ticks; c->c_flags &= ~(CALLOUT_FIRED|CALLOUT_INVOKING); /* * If this timeout is already scheduled and now is moved * earlier, reschedule it now. Otherwise leave it in place * and let it be rescheduled later. */ if (callout_pending(c)) { if (c->c_time - old_time < 0) { CIRCQ_REMOVE(&c->c_list); CIRCQ_INSERT(&c->c_list, &timeout_todo); } } else { c->c_flags |= CALLOUT_PENDING; CIRCQ_INSERT(&c->c_list, &timeout_todo); } CALLOUT_UNLOCK(s); } /* * callout_stop: * * Cancel a pending callout. */ void callout_stop(struct callout *c) { int s; CALLOUT_LOCK(s); if (callout_pending(c)) CIRCQ_REMOVE(&c->c_list); c->c_flags &= ~(CALLOUT_PENDING|CALLOUT_FIRED); CALLOUT_UNLOCK(s); } /* * This is called from hardclock() once every tick. * We return !0 if we need to schedule a softclock. */ int callout_hardclock(void) { int s; int needsoftclock; CALLOUT_LOCK(s); MOVEBUCKET(0, hardclock_ticks); if (MASKWHEEL(0, hardclock_ticks) == 0) { MOVEBUCKET(1, hardclock_ticks); if (MASKWHEEL(1, hardclock_ticks) == 0) { MOVEBUCKET(2, hardclock_ticks); if (MASKWHEEL(2, hardclock_ticks) == 0) MOVEBUCKET(3, hardclock_ticks); } } needsoftclock = !CIRCQ_EMPTY(&timeout_todo); CALLOUT_UNLOCK(s); return needsoftclock; } /* ARGSUSED */ void softclock(void *v) { struct callout *c; void (*func)(void *); void *arg; int s; CALLOUT_LOCK(s); while (!CIRCQ_EMPTY(&timeout_todo)) { c = CIRCQ_FIRST(&timeout_todo); CIRCQ_REMOVE(&c->c_list); /* If due run it, otherwise insert it into the right bucket. */ if (c->c_time - hardclock_ticks > 0) { CIRCQ_INSERT(&c->c_list, BUCKET((c->c_time - hardclock_ticks), c->c_time)); } else { #ifdef CALLOUT_EVENT_COUNTERS if (c->c_time - hardclock_ticks < 0) callout_ev_late.ev_count++; #endif c->c_flags = (c->c_flags & ~CALLOUT_PENDING) | (CALLOUT_FIRED|CALLOUT_INVOKING); func = c->c_func; arg = c->c_arg; CALLOUT_UNLOCK(s); (*func)(arg); CALLOUT_LOCK(s); } } CALLOUT_UNLOCK(s); } #ifdef DDB static void db_show_callout_bucket(struct callout_circq *bucket) { struct callout *c; db_expr_t offset; const char *name; static char question[] = "?"; if (CIRCQ_EMPTY(bucket)) return; for (c = CIRCQ_FIRST(bucket); /*nothing*/; c = CIRCQ_NEXT(&c->c_list)) { db_find_sym_and_offset((db_addr_t)(intptr_t)c->c_func, &name, &offset); name = name ? name : question; #ifdef _LP64 #define POINTER_WIDTH "%16lx" #else #define POINTER_WIDTH "%8lx" #endif db_printf("%9d %2d/%-4d " POINTER_WIDTH " %s\n", c->c_time - hardclock_ticks, (int)((bucket - timeout_wheel) / WHEELSIZE), (int)(bucket - timeout_wheel), (u_long) c->c_arg, name); if (CIRCQ_LAST(&c->c_list, bucket)) break; } } void db_show_callout(db_expr_t addr, int haddr, db_expr_t count, const char *modif) { int b; db_printf("hardclock_ticks now: %d\n", hardclock_ticks); #ifdef _LP64 db_printf(" ticks wheel arg func\n"); #else db_printf(" ticks wheel arg func\n"); #endif /* * Don't lock the callwheel; all the other CPUs are paused * anyhow, and we might be called in a circumstance where * some other CPU was paused while holding the lock. */ db_show_callout_bucket(&timeout_todo); for (b = 0; b < BUCKETS; b++) db_show_callout_bucket(&timeout_wheel[b]); } #endif /* DDB */