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27 * Copyright (c) 2003, 2010, Oracle and/or its affiliates. All rights reserved.
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31 * This file is part of Lustre, http://www.lustre.org/
32 * Lustre is a trademark of Sun Microsystems, Inc.
36 * Library level Event queue management routines
39 #define DEBUG_SUBSYSTEM S_LNET
40 #include <lnet/lib-lnet.h>
43 * Create an event queue that has room for \a count number of events.
45 * The event queue is circular and older events will be overwritten by new
46 * ones if they are not removed in time by the user using the functions
47 * LNetEQGet(), LNetEQWait(), or LNetEQPoll(). It is up to the user to
48 * determine the appropriate size of the event queue to prevent this loss
49 * of events. Note that when EQ handler is specified in \a callback, no
50 * event loss can happen, since the handler is run for each event deposited
53 * \param count The number of events to be stored in the event queue. It
54 * will be rounded up to the next power of two.
55 * \param callback A handler function that runs when an event is deposited
56 * into the EQ. The constant value LNET_EQ_HANDLER_NONE can be used to
57 * indicate that no event handler is desired.
58 * \param handle On successful return, this location will hold a handle for
59 * the newly created EQ.
61 * \retval 0 On success.
62 * \retval -EINVAL If an parameter is not valid.
63 * \retval -ENOMEM If memory for the EQ can't be allocated.
65 * \see lnet_eq_handler_t for the discussion on EQ handler semantics.
68 LNetEQAlloc(unsigned int count, lnet_eq_handler_t callback,
69 lnet_handle_eq_t *handle)
73 LASSERT (the_lnet.ln_init);
74 LASSERT (the_lnet.ln_refcount > 0);
76 /* We need count to be a power of 2 so that when eq_{enq,deq}_seq
77 * overflow, they don't skip entries, so the queue has the same
78 * apparent capacity at all times */
80 if (count != LOWEST_BIT_SET(count)) { /* not a power of 2 already */
81 do { /* knock off all but the top bit... */
82 count &= ~LOWEST_BIT_SET (count);
83 } while (count != LOWEST_BIT_SET(count));
85 count <<= 1; /* ...and round up */
88 if (count == 0) /* catch bad parameter / overflow on roundup */
95 LIBCFS_ALLOC(eq->eq_events, count * sizeof(lnet_event_t));
96 if (eq->eq_events == NULL) {
104 /* NB this resets all event sequence numbers to 0, to be earlier
106 memset(eq->eq_events, 0, count * sizeof(lnet_event_t));
112 eq->eq_callback = callback;
116 lnet_initialise_handle (&eq->eq_lh, LNET_COOKIE_TYPE_EQ);
117 cfs_list_add (&eq->eq_list, &the_lnet.ln_active_eqs);
121 lnet_eq2handle(handle, eq);
126 * Release the resources associated with an event queue if it's idle;
127 * otherwise do nothing and it's up to the user to try again.
129 * \param eqh A handle for the event queue to be released.
131 * \retval 0 If the EQ is not in use and freed.
132 * \retval -ENOENT If \a eqh does not point to a valid EQ.
133 * \retval -EBUSY If the EQ is still in use by some MDs.
136 LNetEQFree(lnet_handle_eq_t eqh)
140 lnet_event_t *events;
142 LASSERT (the_lnet.ln_init);
143 LASSERT (the_lnet.ln_refcount > 0);
147 eq = lnet_handle2eq(&eqh);
153 if (eq->eq_refcount != 0) {
154 CDEBUG(D_NET, "Event queue (%d) busy on destroy.\n",
160 /* stash for free after lock dropped */
161 events = eq->eq_events;
164 lnet_invalidate_handle (&eq->eq_lh);
165 cfs_list_del (&eq->eq_list);
170 LIBCFS_FREE(events, size * sizeof (lnet_event_t));
176 lib_get_event (lnet_eq_t *eq, lnet_event_t *ev)
178 int new_index = eq->eq_deq_seq & (eq->eq_size - 1);
179 lnet_event_t *new_event = &eq->eq_events[new_index];
183 CDEBUG(D_INFO, "event: %p, sequence: %lu, eq->size: %u\n",
184 new_event, eq->eq_deq_seq, eq->eq_size);
186 if (LNET_SEQ_GT (eq->eq_deq_seq, new_event->sequence)) {
190 /* We've got a new event... */
193 /* ...but did it overwrite an event we've not seen yet? */
194 if (eq->eq_deq_seq == new_event->sequence) {
197 /* don't complain with CERROR: some EQs are sized small
198 * anyway; if it's important, the caller should complain */
199 CDEBUG(D_NET, "Event Queue Overflow: eq seq %lu ev seq %lu\n",
200 eq->eq_deq_seq, new_event->sequence);
204 eq->eq_deq_seq = new_event->sequence + 1;
209 * A nonblocking function that can be used to get the next event in an EQ.
210 * If an event handler is associated with the EQ, the handler will run before
211 * this function returns successfully. The event is removed from the queue.
213 * \param eventq A handle for the event queue.
214 * \param event On successful return (1 or -EOVERFLOW), this location will
215 * hold the next event in the EQ.
217 * \retval 0 No pending event in the EQ.
218 * \retval 1 Indicates success.
219 * \retval -ENOENT If \a eventq does not point to a valid EQ.
220 * \retval -EOVERFLOW Indicates success (i.e., an event is returned) and that
221 * at least one event between this event and the last event obtained from the
222 * EQ has been dropped due to limited space in the EQ.
225 LNetEQGet (lnet_handle_eq_t eventq, lnet_event_t *event)
229 return LNetEQPoll(&eventq, 1, 0,
234 * Block the calling process until there is an event in the EQ.
235 * If an event handler is associated with the EQ, the handler will run before
236 * this function returns successfully. This function returns the next event
237 * in the EQ and removes it from the EQ.
239 * \param eventq A handle for the event queue.
240 * \param event On successful return (1 or -EOVERFLOW), this location will
241 * hold the next event in the EQ.
243 * \retval 1 Indicates success.
244 * \retval -ENOENT If \a eventq does not point to a valid EQ.
245 * \retval -EOVERFLOW Indicates success (i.e., an event is returned) and that
246 * at least one event between this event and the last event obtained from the
247 * EQ has been dropped due to limited space in the EQ.
250 LNetEQWait (lnet_handle_eq_t eventq, lnet_event_t *event)
254 return LNetEQPoll(&eventq, 1, LNET_TIME_FOREVER,
259 * Block the calling process until there's an event from a set of EQs or
262 * If an event handler is associated with the EQ, the handler will run before
263 * this function returns successfully, in which case the corresponding event
266 * LNetEQPoll() provides a timeout to allow applications to poll, block for a
267 * fixed period, or block indefinitely.
269 * \param eventqs,neq An array of EQ handles, and size of the array.
270 * \param timeout_ms Time in milliseconds to wait for an event to occur on
271 * one of the EQs. The constant LNET_TIME_FOREVER can be used to indicate an
273 * \param event,which On successful return (1 or -EOVERFLOW), \a event will
274 * hold the next event in the EQs, and \a which will contain the index of the
275 * EQ from which the event was taken.
277 * \retval 0 No pending event in the EQs after timeout.
278 * \retval 1 Indicates success.
279 * \retval -EOVERFLOW Indicates success (i.e., an event is returned) and that
280 * at least one event between this event and the last event obtained from the
281 * EQ indicated by \a which has been dropped due to limited space in the EQ.
282 * \retval -ENOENT If there's an invalid handle in \a eventqs.
285 LNetEQPoll (lnet_handle_eq_t *eventqs, int neq, int timeout_ms,
286 lnet_event_t *event, int *which)
296 # ifdef HAVE_LIBPTHREAD
299 lnet_ni_t *eqwaitni = the_lnet.ln_eqwaitni;
303 LASSERT (the_lnet.ln_init);
304 LASSERT (the_lnet.ln_refcount > 0);
315 /* Recursion breaker */
316 if (the_lnet.ln_rc_state == LNET_RC_STATE_RUNNING &&
317 !LNetHandleIsEqual(eventqs[0], the_lnet.ln_rc_eqh))
318 lnet_router_checker();
322 for (i = 0; i < neq; i++) {
323 lnet_eq_t *eq = lnet_handle2eq(&eventqs[i]);
330 rc = lib_get_event (eq, event);
339 if (timeout_ms == 0) {
344 cfs_waitlink_init(&wl);
345 cfs_set_current_state(CFS_TASK_INTERRUPTIBLE);
346 cfs_waitq_add(&the_lnet.ln_waitq, &wl);
350 if (timeout_ms < 0) {
351 cfs_waitq_wait (&wl, CFS_TASK_INTERRUPTIBLE);
355 now = cfs_time_current();
356 cfs_waitq_timedwait(&wl, CFS_TASK_INTERRUPTIBLE,
357 cfs_time_seconds(timeout_ms)/1000);
358 cfs_duration_usec(cfs_time_sub(cfs_time_current(), now),
360 timeout_ms -= (int)(tv.tv_sec * 1000 + tv.tv_usec / 1000);
366 cfs_waitq_del(&the_lnet.ln_waitq, &wl);
368 if (eqwaitni != NULL) {
369 /* I have a single NI that I have to call into, to get
370 * events queued, or to block. */
371 lnet_ni_addref_locked(eqwaitni);
374 if (timeout_ms <= 0) {
375 (eqwaitni->ni_lnd->lnd_wait)(eqwaitni, timeout_ms);
377 gettimeofday(&then, NULL);
379 (eqwaitni->ni_lnd->lnd_wait)(eqwaitni, timeout_ms);
381 gettimeofday(&now, NULL);
382 timeout_ms -= (now.tv_sec - then.tv_sec) * 1000 +
383 (now.tv_usec - then.tv_usec) / 1000;
389 lnet_ni_decref_locked(eqwaitni);
391 /* don't call into eqwaitni again if timeout has
396 continue; /* go back and check for events */
399 if (timeout_ms == 0) {
404 # ifndef HAVE_LIBPTHREAD
405 /* If I'm single-threaded, LNET fails at startup if it can't
406 * set the_lnet.ln_eqwaitni correctly. */
409 if (timeout_ms < 0) {
410 pthread_cond_wait(&the_lnet.ln_cond,
413 gettimeofday(&then, NULL);
415 ts.tv_sec = then.tv_sec + timeout_ms/1000;
416 ts.tv_nsec = then.tv_usec * 1000 +
417 (timeout_ms%1000) * 1000000;
418 if (ts.tv_nsec >= 1000000000) {
420 ts.tv_nsec -= 1000000000;
423 pthread_cond_timedwait(&the_lnet.ln_cond,
424 &the_lnet.ln_lock, &ts);
426 gettimeofday(&now, NULL);
427 timeout_ms -= (now.tv_sec - then.tv_sec) * 1000 +
428 (now.tv_usec - then.tv_usec) / 1000;