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27 * Copyright (c) 2003, 2010, Oracle and/or its affiliates. All rights reserved.
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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) {
102 /* NB this resets all event sequence numbers to 0, to be earlier
104 memset(eq->eq_events, 0, count * sizeof(lnet_event_t));
110 eq->eq_callback = callback;
114 lnet_res_lh_initialize(&the_lnet.ln_eq_container, &eq->eq_lh);
115 cfs_list_add(&eq->eq_list, &the_lnet.ln_eq_container.rec_active);
119 lnet_eq2handle(handle, eq);
124 * Release the resources associated with an event queue if it's idle;
125 * otherwise do nothing and it's up to the user to try again.
127 * \param eqh A handle for the event queue to be released.
129 * \retval 0 If the EQ is not in use and freed.
130 * \retval -ENOENT If \a eqh does not point to a valid EQ.
131 * \retval -EBUSY If the EQ is still in use by some MDs.
134 LNetEQFree(lnet_handle_eq_t eqh)
138 lnet_event_t *events;
140 LASSERT (the_lnet.ln_init);
141 LASSERT (the_lnet.ln_refcount > 0);
145 eq = lnet_handle2eq(&eqh);
151 if (eq->eq_refcount != 0) {
152 CDEBUG(D_NET, "Event queue (%d) busy on destroy.\n",
158 /* stash for free after lock dropped */
159 events = eq->eq_events;
162 lnet_res_lh_invalidate(&eq->eq_lh);
163 cfs_list_del (&eq->eq_list);
164 lnet_eq_free_locked(eq);
168 LIBCFS_FREE(events, size * sizeof (lnet_event_t));
174 lib_get_event (lnet_eq_t *eq, lnet_event_t *ev)
176 int new_index = eq->eq_deq_seq & (eq->eq_size - 1);
177 lnet_event_t *new_event = &eq->eq_events[new_index];
181 CDEBUG(D_INFO, "event: %p, sequence: %lu, eq->size: %u\n",
182 new_event, eq->eq_deq_seq, eq->eq_size);
184 if (LNET_SEQ_GT (eq->eq_deq_seq, new_event->sequence)) {
188 /* We've got a new event... */
191 /* ...but did it overwrite an event we've not seen yet? */
192 if (eq->eq_deq_seq == new_event->sequence) {
195 /* don't complain with CERROR: some EQs are sized small
196 * anyway; if it's important, the caller should complain */
197 CDEBUG(D_NET, "Event Queue Overflow: eq seq %lu ev seq %lu\n",
198 eq->eq_deq_seq, new_event->sequence);
202 eq->eq_deq_seq = new_event->sequence + 1;
207 * A nonblocking function that can be used to get the next event in an EQ.
208 * If an event handler is associated with the EQ, the handler will run before
209 * this function returns successfully. The event is removed from the queue.
211 * \param eventq A handle for the event queue.
212 * \param event On successful return (1 or -EOVERFLOW), this location will
213 * hold the next event in the EQ.
215 * \retval 0 No pending event in the EQ.
216 * \retval 1 Indicates success.
217 * \retval -ENOENT If \a eventq does not point to a valid EQ.
218 * \retval -EOVERFLOW Indicates success (i.e., an event is returned) and that
219 * at least one event between this event and the last event obtained from the
220 * EQ has been dropped due to limited space in the EQ.
223 LNetEQGet (lnet_handle_eq_t eventq, lnet_event_t *event)
227 return LNetEQPoll(&eventq, 1, 0,
232 * Block the calling process until there is an event in the EQ.
233 * If an event handler is associated with the EQ, the handler will run before
234 * this function returns successfully. This function returns the next event
235 * in the EQ and removes it from the EQ.
237 * \param eventq A handle for the event queue.
238 * \param event On successful return (1 or -EOVERFLOW), this location will
239 * hold the next event in the EQ.
241 * \retval 1 Indicates success.
242 * \retval -ENOENT If \a eventq does not point to a valid EQ.
243 * \retval -EOVERFLOW Indicates success (i.e., an event is returned) and that
244 * at least one event between this event and the last event obtained from the
245 * EQ has been dropped due to limited space in the EQ.
248 LNetEQWait (lnet_handle_eq_t eventq, lnet_event_t *event)
252 return LNetEQPoll(&eventq, 1, LNET_TIME_FOREVER,
257 * Block the calling process until there's an event from a set of EQs or
260 * If an event handler is associated with the EQ, the handler will run before
261 * this function returns successfully, in which case the corresponding event
264 * LNetEQPoll() provides a timeout to allow applications to poll, block for a
265 * fixed period, or block indefinitely.
267 * \param eventqs,neq An array of EQ handles, and size of the array.
268 * \param timeout_ms Time in milliseconds to wait for an event to occur on
269 * one of the EQs. The constant LNET_TIME_FOREVER can be used to indicate an
271 * \param event,which On successful return (1 or -EOVERFLOW), \a event will
272 * hold the next event in the EQs, and \a which will contain the index of the
273 * EQ from which the event was taken.
275 * \retval 0 No pending event in the EQs after timeout.
276 * \retval 1 Indicates success.
277 * \retval -EOVERFLOW Indicates success (i.e., an event is returned) and that
278 * at least one event between this event and the last event obtained from the
279 * EQ indicated by \a which has been dropped due to limited space in the EQ.
280 * \retval -ENOENT If there's an invalid handle in \a eventqs.
283 LNetEQPoll (lnet_handle_eq_t *eventqs, int neq, int timeout_ms,
284 lnet_event_t *event, int *which)
294 # ifdef HAVE_LIBPTHREAD
297 lnet_ni_t *eqwaitni = the_lnet.ln_eqwaitni;
301 LASSERT (the_lnet.ln_init);
302 LASSERT (the_lnet.ln_refcount > 0);
313 /* Recursion breaker */
314 if (the_lnet.ln_rc_state == LNET_RC_STATE_RUNNING &&
315 !LNetHandleIsEqual(eventqs[0], the_lnet.ln_rc_eqh))
316 lnet_router_checker();
320 for (i = 0; i < neq; i++) {
321 lnet_eq_t *eq = lnet_handle2eq(&eventqs[i]);
328 rc = lib_get_event (eq, event);
337 if (timeout_ms == 0) {
342 cfs_waitlink_init(&wl);
343 cfs_set_current_state(CFS_TASK_INTERRUPTIBLE);
344 cfs_waitq_add(&the_lnet.ln_waitq, &wl);
348 if (timeout_ms < 0) {
349 cfs_waitq_wait (&wl, CFS_TASK_INTERRUPTIBLE);
353 now = cfs_time_current();
354 cfs_waitq_timedwait(&wl, CFS_TASK_INTERRUPTIBLE,
355 cfs_time_seconds(timeout_ms)/1000);
356 cfs_duration_usec(cfs_time_sub(cfs_time_current(), now),
358 timeout_ms -= (int)(tv.tv_sec * 1000 + tv.tv_usec / 1000);
364 cfs_waitq_del(&the_lnet.ln_waitq, &wl);
366 if (eqwaitni != NULL) {
367 /* I have a single NI that I have to call into, to get
368 * events queued, or to block. */
369 lnet_ni_addref_locked(eqwaitni);
372 if (timeout_ms <= 0) {
373 (eqwaitni->ni_lnd->lnd_wait)(eqwaitni, timeout_ms);
375 gettimeofday(&then, NULL);
377 (eqwaitni->ni_lnd->lnd_wait)(eqwaitni, timeout_ms);
379 gettimeofday(&now, NULL);
380 timeout_ms -= (now.tv_sec - then.tv_sec) * 1000 +
381 (now.tv_usec - then.tv_usec) / 1000;
387 lnet_ni_decref_locked(eqwaitni);
389 /* don't call into eqwaitni again if timeout has
394 continue; /* go back and check for events */
397 if (timeout_ms == 0) {
402 # ifndef HAVE_LIBPTHREAD
403 /* If I'm single-threaded, LNET fails at startup if it can't
404 * set the_lnet.ln_eqwaitni correctly. */
407 if (timeout_ms < 0) {
408 pthread_cond_wait(&the_lnet.ln_cond,
411 gettimeofday(&then, NULL);
413 ts.tv_sec = then.tv_sec + timeout_ms/1000;
414 ts.tv_nsec = then.tv_usec * 1000 +
415 (timeout_ms%1000) * 1000000;
416 if (ts.tv_nsec >= 1000000000) {
418 ts.tv_nsec -= 1000000000;
421 pthread_cond_timedwait(&the_lnet.ln_cond,
422 &the_lnet.ln_lock, &ts);
424 gettimeofday(&now, NULL);
425 timeout_ms -= (now.tv_sec - then.tv_sec) * 1000 +
426 (now.tv_usec - then.tv_usec) / 1000;