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36 * lnet/selftest/timer.c
38 * Author: Isaac Huang <isaac@clusterfs.com>
41 #define DEBUG_SUBSYSTEM S_LNET
46 * Timers are implemented as a sorted queue of expiry times. The queue
47 * is slotted, with each slot holding timers which expire in a
48 * 2**STTIMER_MINPOLL (8) second period. The timers in each slot are
49 * sorted by increasing expiry time. The number of slots is 2**7 (128),
50 * to cover a time period of 1024 seconds into the future before wrapping.
52 #define STTIMER_MINPOLL 3 /* log2 min poll interval (8 s) */
53 #define STTIMER_SLOTTIME (1 << STTIMER_MINPOLL)
54 #define STTIMER_SLOTTIMEMASK (~(STTIMER_SLOTTIME - 1))
55 #define STTIMER_NSLOTS (1 << 7)
56 #define STTIMER_SLOT(t) (&stt_data.stt_hash[(((t) >> STTIMER_MINPOLL) & \
57 (STTIMER_NSLOTS - 1))])
59 static struct st_timer_data {
61 unsigned long stt_prev_slot; /* start time of the slot processed
63 struct list_head stt_hash[STTIMER_NSLOTS];
65 wait_queue_head_t stt_waitq;
70 stt_add_timer(stt_timer_t *timer)
72 struct list_head *pos;
74 spin_lock(&stt_data.stt_lock);
76 LASSERT(stt_data.stt_nthreads > 0);
77 LASSERT(!stt_data.stt_shuttingdown);
78 LASSERT(timer->stt_func != NULL);
79 LASSERT(list_empty(&timer->stt_list));
80 LASSERT(timer->stt_expires > ktime_get_real_seconds());
82 /* a simple insertion sort */
83 list_for_each_prev(pos, STTIMER_SLOT(timer->stt_expires)) {
84 stt_timer_t *old = list_entry(pos, stt_timer_t, stt_list);
86 if (timer->stt_expires >= old->stt_expires)
89 list_add(&timer->stt_list, pos);
91 spin_unlock(&stt_data.stt_lock);
95 * The function returns whether it has deactivated a pending timer or not.
96 * (ie. del_timer() of an inactive timer returns 0, del_timer() of an
97 * active timer returns 1.)
100 * When 0 is returned, it is possible that timer->stt_func _is_ running on
104 stt_del_timer(stt_timer_t *timer)
108 spin_lock(&stt_data.stt_lock);
110 LASSERT(stt_data.stt_nthreads > 0);
111 LASSERT(!stt_data.stt_shuttingdown);
113 if (!list_empty(&timer->stt_list)) {
115 list_del_init(&timer->stt_list);
118 spin_unlock(&stt_data.stt_lock);
122 /* called with stt_data.stt_lock held */
124 stt_expire_list(struct list_head *slot, time64_t now)
129 while (!list_empty(slot)) {
130 timer = list_entry(slot->next, stt_timer_t, stt_list);
132 if (timer->stt_expires > now)
135 list_del_init(&timer->stt_list);
136 spin_unlock(&stt_data.stt_lock);
139 (*timer->stt_func) (timer->stt_data);
141 spin_lock(&stt_data.stt_lock);
148 stt_check_timers(unsigned long *last)
152 unsigned long this_slot;
154 now = ktime_get_real_seconds();
155 this_slot = now & STTIMER_SLOTTIMEMASK;
157 spin_lock(&stt_data.stt_lock);
159 while (cfs_time_aftereq(this_slot, *last)) {
160 expired += stt_expire_list(STTIMER_SLOT(this_slot), now);
161 this_slot = cfs_time_sub(this_slot, STTIMER_SLOTTIME);
164 *last = now & STTIMER_SLOTTIMEMASK;
165 spin_unlock(&stt_data.stt_lock);
170 stt_timer_main(void *arg)
174 while (!stt_data.stt_shuttingdown) {
175 stt_check_timers(&stt_data.stt_prev_slot);
177 wait_event_timeout(stt_data.stt_waitq,
178 stt_data.stt_shuttingdown,
179 cfs_time_seconds(STTIMER_SLOTTIME));
182 spin_lock(&stt_data.stt_lock);
183 stt_data.stt_nthreads--;
184 spin_unlock(&stt_data.stt_lock);
189 stt_start_timer_thread(void)
191 struct task_struct *task;
193 LASSERT(!stt_data.stt_shuttingdown);
195 task = kthread_run(stt_timer_main, NULL, "st_timer");
197 return PTR_ERR(task);
199 spin_lock(&stt_data.stt_lock);
200 stt_data.stt_nthreads++;
201 spin_unlock(&stt_data.stt_lock);
211 stt_data.stt_shuttingdown = 0;
212 stt_data.stt_prev_slot = ktime_get_real_seconds() & STTIMER_SLOTTIMEMASK;
214 spin_lock_init(&stt_data.stt_lock);
215 for (i = 0; i < STTIMER_NSLOTS; i++)
216 INIT_LIST_HEAD(&stt_data.stt_hash[i]);
218 stt_data.stt_nthreads = 0;
219 init_waitqueue_head(&stt_data.stt_waitq);
220 rc = stt_start_timer_thread();
222 CERROR("Can't spawn timer thread: %d\n", rc);
232 spin_lock(&stt_data.stt_lock);
234 for (i = 0; i < STTIMER_NSLOTS; i++)
235 LASSERT(list_empty(&stt_data.stt_hash[i]));
237 stt_data.stt_shuttingdown = 1;
239 wake_up(&stt_data.stt_waitq);
240 lst_wait_until(stt_data.stt_nthreads == 0, stt_data.stt_lock,
241 "waiting for %d threads to terminate\n",
242 stt_data.stt_nthreads);
244 spin_unlock(&stt_data.stt_lock);