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35 * Derived from FreeBSD's bufring.h
37 **************************************************************************
39 * Copyright (c) 2007-2009 Kip Macy kmacy@freebsd.org
40 * All rights reserved.
42 * Redistribution and use in source and binary forms, with or without
43 * modification, are permitted provided that the following conditions are met:
45 * 1. Redistributions of source code must retain the above copyright notice,
46 * this list of conditions and the following disclaimer.
48 * 2. The name of Kip Macy nor the names of other
49 * contributors may be used to endorse or promote products derived from
50 * this software without specific prior written permission.
52 * THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS "AS IS"
53 * AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE
54 * IMPLIED WARRANTIES OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE
55 * ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT OWNER OR CONTRIBUTORS BE
56 * LIABLE FOR ANY DIRECT, INDIRECT, INCIDENTAL, SPECIAL, EXEMPLARY, OR
57 * CONSEQUENTIAL DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF
58 * SUBSTITUTE GOODS OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS
59 * INTERRUPTION) HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN
60 * CONTRACT, STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE)
61 * ARISING IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
62 * POSSIBILITY OF SUCH DAMAGE.
64 ***************************************************************************/
73 * The Ring Manager is a fixed-size queue, implemented as a table of
74 * pointers. Head and tail pointers are modified atomically, allowing
75 * concurrent access to it. It has the following features:
77 * - FIFO (First In First Out)
78 * - Maximum size is fixed; the pointers are stored in a table.
79 * - Lockless implementation.
80 * - Multi- or single-consumer dequeue.
81 * - Multi- or single-producer enqueue.
85 * Note: the ring implementation is not preemptable. A lcore must not
86 * be interrupted by another task that uses the same ring.
96 #include <sys/queue.h>
98 #include <rte_common.h>
99 #include <rte_memory.h>
100 #include <rte_lcore.h>
101 #include <rte_atomic.h>
102 #include <rte_branch_prediction.h>
103 #include <rte_memzone.h>
104 #include <rte_pause.h>
106 #define RTE_TAILQ_RING_NAME "RTE_RING"
108 enum rte_ring_queue_behavior {
109 RTE_RING_QUEUE_FIXED = 0, /* Enq/Deq a fixed number of items from a ring */
110 RTE_RING_QUEUE_VARIABLE /* Enq/Deq as many items as possible from ring */
113 #define RTE_RING_MZ_PREFIX "RG_"
114 /**< The maximum length of a ring name. */
115 #define RTE_RING_NAMESIZE (RTE_MEMZONE_NAMESIZE - \
116 sizeof(RTE_RING_MZ_PREFIX) + 1)
118 struct rte_memzone; /* forward declaration, so as not to require memzone.h */
120 #if RTE_CACHE_LINE_SIZE < 128
121 #define PROD_ALIGN (RTE_CACHE_LINE_SIZE * 2)
122 #define CONS_ALIGN (RTE_CACHE_LINE_SIZE * 2)
124 #define PROD_ALIGN RTE_CACHE_LINE_SIZE
125 #define CONS_ALIGN RTE_CACHE_LINE_SIZE
128 /* structure to hold a pair of head/tail values and other metadata */
129 struct rte_ring_headtail {
130 volatile uint32_t head; /**< Prod/consumer head. */
131 volatile uint32_t tail; /**< Prod/consumer tail. */
132 uint32_t single; /**< True if single prod/cons */
136 * An RTE ring structure.
138 * The producer and the consumer have a head and a tail index. The particularity
139 * of these index is that they are not between 0 and size(ring). These indexes
140 * are between 0 and 2^32, and we mask their value when we access the ring[]
141 * field. Thanks to this assumption, we can do subtractions between 2 index
142 * values in a modulo-32bit base: that's why the overflow of the indexes is not
147 * Note: this field kept the RTE_MEMZONE_NAMESIZE size due to ABI
148 * compatibility requirements, it could be changed to RTE_RING_NAMESIZE
149 * next time the ABI changes
151 char name[RTE_MEMZONE_NAMESIZE] __rte_cache_aligned; /**< Name of the ring. */
152 int flags; /**< Flags supplied at creation. */
153 const struct rte_memzone *memzone;
154 /**< Memzone, if any, containing the rte_ring */
155 uint32_t size; /**< Size of ring. */
156 uint32_t mask; /**< Mask (size-1) of ring. */
157 uint32_t capacity; /**< Usable size of ring */
159 /** Ring producer status. */
160 struct rte_ring_headtail prod __rte_aligned(PROD_ALIGN);
162 /** Ring consumer status. */
163 struct rte_ring_headtail cons __rte_aligned(CONS_ALIGN);
166 #define RING_F_SP_ENQ 0x0001 /**< The default enqueue is "single-producer". */
167 #define RING_F_SC_DEQ 0x0002 /**< The default dequeue is "single-consumer". */
169 * Ring is to hold exactly requested number of entries.
170 * Without this flag set, the ring size requested must be a power of 2, and the
171 * usable space will be that size - 1. With the flag, the requested size will
172 * be rounded up to the next power of two, but the usable space will be exactly
173 * that requested. Worst case, if a power-of-2 size is requested, half the
174 * ring space will be wasted.
176 #define RING_F_EXACT_SZ 0x0004
177 #define RTE_RING_SZ_MASK (unsigned)(0x0fffffff) /**< Ring size mask */
179 /* @internal defines for passing to the enqueue dequeue worker functions */
186 * Calculate the memory size needed for a ring
188 * This function returns the number of bytes needed for a ring, given
189 * the number of elements in it. This value is the sum of the size of
190 * the structure rte_ring and the size of the memory needed by the
191 * objects pointers. The value is aligned to a cache line size.
194 * The number of elements in the ring (must be a power of 2).
196 * - The memory size needed for the ring on success.
197 * - -EINVAL if count is not a power of 2.
199 ssize_t rte_ring_get_memsize(unsigned count);
202 * Initialize a ring structure.
204 * Initialize a ring structure in memory pointed by "r". The size of the
205 * memory area must be large enough to store the ring structure and the
206 * object table. It is advised to use rte_ring_get_memsize() to get the
209 * The ring size is set to *count*, which must be a power of two. Water
210 * marking is disabled by default. The real usable ring size is
211 * *count-1* instead of *count* to differentiate a free ring from an
214 * The ring is not added in RTE_TAILQ_RING global list. Indeed, the
215 * memory given by the caller may not be shareable among dpdk
219 * The pointer to the ring structure followed by the objects table.
221 * The name of the ring.
223 * The number of elements in the ring (must be a power of 2).
225 * An OR of the following:
226 * - RING_F_SP_ENQ: If this flag is set, the default behavior when
227 * using ``rte_ring_enqueue()`` or ``rte_ring_enqueue_bulk()``
228 * is "single-producer". Otherwise, it is "multi-producers".
229 * - RING_F_SC_DEQ: If this flag is set, the default behavior when
230 * using ``rte_ring_dequeue()`` or ``rte_ring_dequeue_bulk()``
231 * is "single-consumer". Otherwise, it is "multi-consumers".
233 * 0 on success, or a negative value on error.
235 int rte_ring_init(struct rte_ring *r, const char *name, unsigned count,
239 * Create a new ring named *name* in memory.
241 * This function uses ``memzone_reserve()`` to allocate memory. Then it
242 * calls rte_ring_init() to initialize an empty ring.
244 * The new ring size is set to *count*, which must be a power of
245 * two. Water marking is disabled by default. The real usable ring size
246 * is *count-1* instead of *count* to differentiate a free ring from an
249 * The ring is added in RTE_TAILQ_RING list.
252 * The name of the ring.
254 * The size of the ring (must be a power of 2).
256 * The *socket_id* argument is the socket identifier in case of
257 * NUMA. The value can be *SOCKET_ID_ANY* if there is no NUMA
258 * constraint for the reserved zone.
260 * An OR of the following:
261 * - RING_F_SP_ENQ: If this flag is set, the default behavior when
262 * using ``rte_ring_enqueue()`` or ``rte_ring_enqueue_bulk()``
263 * is "single-producer". Otherwise, it is "multi-producers".
264 * - RING_F_SC_DEQ: If this flag is set, the default behavior when
265 * using ``rte_ring_dequeue()`` or ``rte_ring_dequeue_bulk()``
266 * is "single-consumer". Otherwise, it is "multi-consumers".
268 * On success, the pointer to the new allocated ring. NULL on error with
269 * rte_errno set appropriately. Possible errno values include:
270 * - E_RTE_NO_CONFIG - function could not get pointer to rte_config structure
271 * - E_RTE_SECONDARY - function was called from a secondary process instance
272 * - EINVAL - count provided is not a power of 2
273 * - ENOSPC - the maximum number of memzones has already been allocated
274 * - EEXIST - a memzone with the same name already exists
275 * - ENOMEM - no appropriate memory area found in which to create memzone
277 struct rte_ring *rte_ring_create(const char *name, unsigned count,
278 int socket_id, unsigned flags);
280 * De-allocate all memory used by the ring.
285 void rte_ring_free(struct rte_ring *r);
288 * Dump the status of the ring to a file.
291 * A pointer to a file for output
293 * A pointer to the ring structure.
295 void rte_ring_dump(FILE *f, const struct rte_ring *r);
297 /* the actual enqueue of pointers on the ring.
298 * Placed here since identical code needed in both
299 * single and multi producer enqueue functions */
300 #define ENQUEUE_PTRS(r, ring_start, prod_head, obj_table, n, obj_type) do { \
302 const uint32_t size = (r)->size; \
303 uint32_t idx = prod_head & (r)->mask; \
304 obj_type *ring = (obj_type *)ring_start; \
305 if (likely(idx + n < size)) { \
306 for (i = 0; i < (n & ((~(unsigned)0x3))); i+=4, idx+=4) { \
307 ring[idx] = obj_table[i]; \
308 ring[idx+1] = obj_table[i+1]; \
309 ring[idx+2] = obj_table[i+2]; \
310 ring[idx+3] = obj_table[i+3]; \
314 ring[idx++] = obj_table[i++]; /* fallthrough */ \
316 ring[idx++] = obj_table[i++]; /* fallthrough */ \
318 ring[idx++] = obj_table[i++]; \
321 for (i = 0; idx < size; i++, idx++)\
322 ring[idx] = obj_table[i]; \
323 for (idx = 0; i < n; i++, idx++) \
324 ring[idx] = obj_table[i]; \
328 /* the actual copy of pointers on the ring to obj_table.
329 * Placed here since identical code needed in both
330 * single and multi consumer dequeue functions */
331 #define DEQUEUE_PTRS(r, ring_start, cons_head, obj_table, n, obj_type) do { \
333 uint32_t idx = cons_head & (r)->mask; \
334 const uint32_t size = (r)->size; \
335 obj_type *ring = (obj_type *)ring_start; \
336 if (likely(idx + n < size)) { \
337 for (i = 0; i < (n & (~(unsigned)0x3)); i+=4, idx+=4) {\
338 obj_table[i] = ring[idx]; \
339 obj_table[i+1] = ring[idx+1]; \
340 obj_table[i+2] = ring[idx+2]; \
341 obj_table[i+3] = ring[idx+3]; \
345 obj_table[i++] = ring[idx++]; /* fallthrough */ \
347 obj_table[i++] = ring[idx++]; /* fallthrough */ \
349 obj_table[i++] = ring[idx++]; \
352 for (i = 0; idx < size; i++, idx++) \
353 obj_table[i] = ring[idx]; \
354 for (idx = 0; i < n; i++, idx++) \
355 obj_table[i] = ring[idx]; \
359 static __rte_always_inline void
360 update_tail(struct rte_ring_headtail *ht, uint32_t old_val, uint32_t new_val,
364 * If there are other enqueues/dequeues in progress that preceded us,
365 * we need to wait for them to complete
368 while (unlikely(ht->tail != old_val))
375 * @internal This function updates the producer head for enqueue
378 * A pointer to the ring structure
380 * Indicates whether multi-producer path is needed or not
382 * The number of elements we will want to enqueue, i.e. how far should the
385 * RTE_RING_QUEUE_FIXED: Enqueue a fixed number of items from a ring
386 * RTE_RING_QUEUE_VARIABLE: Enqueue as many items as possible from ring
388 * Returns head value as it was before the move, i.e. where enqueue starts
390 * Returns the current/new head value i.e. where enqueue finishes
391 * @param free_entries
392 * Returns the amount of free space in the ring BEFORE head was moved
394 * Actual number of objects enqueued.
395 * If behavior == RTE_RING_QUEUE_FIXED, this will be 0 or n only.
397 static __rte_always_inline unsigned int
398 __rte_ring_move_prod_head(struct rte_ring *r, int is_sp,
399 unsigned int n, enum rte_ring_queue_behavior behavior,
400 uint32_t *old_head, uint32_t *new_head,
401 uint32_t *free_entries)
403 const uint32_t capacity = r->capacity;
404 unsigned int max = n;
408 /* Reset n to the initial burst count */
411 *old_head = r->prod.head;
412 const uint32_t cons_tail = r->cons.tail;
414 * The subtraction is done between two unsigned 32bits value
415 * (the result is always modulo 32 bits even if we have
416 * *old_head > cons_tail). So 'free_entries' is always between 0
417 * and capacity (which is < size).
419 *free_entries = (capacity + cons_tail - *old_head);
421 /* check that we have enough room in ring */
422 if (unlikely(n > *free_entries))
423 n = (behavior == RTE_RING_QUEUE_FIXED) ?
429 *new_head = *old_head + n;
431 r->prod.head = *new_head, success = 1;
433 success = rte_atomic32_cmpset(&r->prod.head,
434 *old_head, *new_head);
435 } while (unlikely(success == 0));
440 * @internal Enqueue several objects on the ring
443 * A pointer to the ring structure.
445 * A pointer to a table of void * pointers (objects).
447 * The number of objects to add in the ring from the obj_table.
449 * RTE_RING_QUEUE_FIXED: Enqueue a fixed number of items from a ring
450 * RTE_RING_QUEUE_VARIABLE: Enqueue as many items as possible from ring
452 * Indicates whether to use single producer or multi-producer head update
454 * returns the amount of space after the enqueue operation has finished
456 * Actual number of objects enqueued.
457 * If behavior == RTE_RING_QUEUE_FIXED, this will be 0 or n only.
459 static __rte_always_inline unsigned int
460 __rte_ring_do_enqueue(struct rte_ring *r, void * const *obj_table,
461 unsigned int n, enum rte_ring_queue_behavior behavior,
462 int is_sp, unsigned int *free_space)
464 uint32_t prod_head, prod_next;
465 uint32_t free_entries;
467 n = __rte_ring_move_prod_head(r, is_sp, n, behavior,
468 &prod_head, &prod_next, &free_entries);
472 ENQUEUE_PTRS(r, &r[1], prod_head, obj_table, n, void *);
475 update_tail(&r->prod, prod_head, prod_next, is_sp);
477 if (free_space != NULL)
478 *free_space = free_entries - n;
483 * @internal This function updates the consumer head for dequeue
486 * A pointer to the ring structure
488 * Indicates whether multi-consumer path is needed or not
490 * The number of elements we will want to enqueue, i.e. how far should the
493 * RTE_RING_QUEUE_FIXED: Dequeue a fixed number of items from a ring
494 * RTE_RING_QUEUE_VARIABLE: Dequeue as many items as possible from ring
496 * Returns head value as it was before the move, i.e. where dequeue starts
498 * Returns the current/new head value i.e. where dequeue finishes
500 * Returns the number of entries in the ring BEFORE head was moved
502 * - Actual number of objects dequeued.
503 * If behavior == RTE_RING_QUEUE_FIXED, this will be 0 or n only.
505 static __rte_always_inline unsigned int
506 __rte_ring_move_cons_head(struct rte_ring *r, int is_sc,
507 unsigned int n, enum rte_ring_queue_behavior behavior,
508 uint32_t *old_head, uint32_t *new_head,
511 unsigned int max = n;
514 /* move cons.head atomically */
516 /* Restore n as it may change every loop */
519 *old_head = r->cons.head;
520 const uint32_t prod_tail = r->prod.tail;
521 /* The subtraction is done between two unsigned 32bits value
522 * (the result is always modulo 32 bits even if we have
523 * cons_head > prod_tail). So 'entries' is always between 0
524 * and size(ring)-1. */
525 *entries = (prod_tail - *old_head);
527 /* Set the actual entries for dequeue */
529 n = (behavior == RTE_RING_QUEUE_FIXED) ? 0 : *entries;
531 if (unlikely(n == 0))
534 *new_head = *old_head + n;
536 r->cons.head = *new_head, success = 1;
538 success = rte_atomic32_cmpset(&r->cons.head, *old_head,
540 } while (unlikely(success == 0));
545 * @internal Dequeue several objects from the ring
548 * A pointer to the ring structure.
550 * A pointer to a table of void * pointers (objects).
552 * The number of objects to pull from the ring.
554 * RTE_RING_QUEUE_FIXED: Dequeue a fixed number of items from a ring
555 * RTE_RING_QUEUE_VARIABLE: Dequeue as many items as possible from ring
557 * Indicates whether to use single consumer or multi-consumer head update
559 * returns the number of remaining ring entries after the dequeue has finished
561 * - Actual number of objects dequeued.
562 * If behavior == RTE_RING_QUEUE_FIXED, this will be 0 or n only.
564 static __rte_always_inline unsigned int
565 __rte_ring_do_dequeue(struct rte_ring *r, void **obj_table,
566 unsigned int n, enum rte_ring_queue_behavior behavior,
567 int is_sc, unsigned int *available)
569 uint32_t cons_head, cons_next;
572 n = __rte_ring_move_cons_head(r, is_sc, n, behavior,
573 &cons_head, &cons_next, &entries);
577 DEQUEUE_PTRS(r, &r[1], cons_head, obj_table, n, void *);
580 update_tail(&r->cons, cons_head, cons_next, is_sc);
583 if (available != NULL)
584 *available = entries - n;
589 * Enqueue several objects on the ring (multi-producers safe).
591 * This function uses a "compare and set" instruction to move the
592 * producer index atomically.
595 * A pointer to the ring structure.
597 * A pointer to a table of void * pointers (objects).
599 * The number of objects to add in the ring from the obj_table.
601 * if non-NULL, returns the amount of space in the ring after the
602 * enqueue operation has finished.
604 * The number of objects enqueued, either 0 or n
606 static __rte_always_inline unsigned int
607 rte_ring_mp_enqueue_bulk(struct rte_ring *r, void * const *obj_table,
608 unsigned int n, unsigned int *free_space)
610 return __rte_ring_do_enqueue(r, obj_table, n, RTE_RING_QUEUE_FIXED,
611 __IS_MP, free_space);
615 * Enqueue several objects on a ring (NOT multi-producers safe).
618 * A pointer to the ring structure.
620 * A pointer to a table of void * pointers (objects).
622 * The number of objects to add in the ring from the obj_table.
624 * if non-NULL, returns the amount of space in the ring after the
625 * enqueue operation has finished.
627 * The number of objects enqueued, either 0 or n
629 static __rte_always_inline unsigned int
630 rte_ring_sp_enqueue_bulk(struct rte_ring *r, void * const *obj_table,
631 unsigned int n, unsigned int *free_space)
633 return __rte_ring_do_enqueue(r, obj_table, n, RTE_RING_QUEUE_FIXED,
634 __IS_SP, free_space);
638 * Enqueue several objects on a ring.
640 * This function calls the multi-producer or the single-producer
641 * version depending on the default behavior that was specified at
642 * ring creation time (see flags).
645 * A pointer to the ring structure.
647 * A pointer to a table of void * pointers (objects).
649 * The number of objects to add in the ring from the obj_table.
651 * if non-NULL, returns the amount of space in the ring after the
652 * enqueue operation has finished.
654 * The number of objects enqueued, either 0 or n
656 static __rte_always_inline unsigned int
657 rte_ring_enqueue_bulk(struct rte_ring *r, void * const *obj_table,
658 unsigned int n, unsigned int *free_space)
660 return __rte_ring_do_enqueue(r, obj_table, n, RTE_RING_QUEUE_FIXED,
661 r->prod.single, free_space);
665 * Enqueue one object on a ring (multi-producers safe).
667 * This function uses a "compare and set" instruction to move the
668 * producer index atomically.
671 * A pointer to the ring structure.
673 * A pointer to the object to be added.
675 * - 0: Success; objects enqueued.
676 * - -ENOBUFS: Not enough room in the ring to enqueue; no object is enqueued.
678 static __rte_always_inline int
679 rte_ring_mp_enqueue(struct rte_ring *r, void *obj)
681 return rte_ring_mp_enqueue_bulk(r, &obj, 1, NULL) ? 0 : -ENOBUFS;
685 * Enqueue one object on a ring (NOT multi-producers safe).
688 * A pointer to the ring structure.
690 * A pointer to the object to be added.
692 * - 0: Success; objects enqueued.
693 * - -ENOBUFS: Not enough room in the ring to enqueue; no object is enqueued.
695 static __rte_always_inline int
696 rte_ring_sp_enqueue(struct rte_ring *r, void *obj)
698 return rte_ring_sp_enqueue_bulk(r, &obj, 1, NULL) ? 0 : -ENOBUFS;
702 * Enqueue one object on a ring.
704 * This function calls the multi-producer or the single-producer
705 * version, depending on the default behaviour that was specified at
706 * ring creation time (see flags).
709 * A pointer to the ring structure.
711 * A pointer to the object to be added.
713 * - 0: Success; objects enqueued.
714 * - -ENOBUFS: Not enough room in the ring to enqueue; no object is enqueued.
716 static __rte_always_inline int
717 rte_ring_enqueue(struct rte_ring *r, void *obj)
719 return rte_ring_enqueue_bulk(r, &obj, 1, NULL) ? 0 : -ENOBUFS;
723 * Dequeue several objects from a ring (multi-consumers safe).
725 * This function uses a "compare and set" instruction to move the
726 * consumer index atomically.
729 * A pointer to the ring structure.
731 * A pointer to a table of void * pointers (objects) that will be filled.
733 * The number of objects to dequeue from the ring to the obj_table.
735 * If non-NULL, returns the number of remaining ring entries after the
736 * dequeue has finished.
738 * The number of objects dequeued, either 0 or n
740 static __rte_always_inline unsigned int
741 rte_ring_mc_dequeue_bulk(struct rte_ring *r, void **obj_table,
742 unsigned int n, unsigned int *available)
744 return __rte_ring_do_dequeue(r, obj_table, n, RTE_RING_QUEUE_FIXED,
749 * Dequeue several objects from a ring (NOT multi-consumers safe).
752 * A pointer to the ring structure.
754 * A pointer to a table of void * pointers (objects) that will be filled.
756 * The number of objects to dequeue from the ring to the obj_table,
757 * must be strictly positive.
759 * If non-NULL, returns the number of remaining ring entries after the
760 * dequeue has finished.
762 * The number of objects dequeued, either 0 or n
764 static __rte_always_inline unsigned int
765 rte_ring_sc_dequeue_bulk(struct rte_ring *r, void **obj_table,
766 unsigned int n, unsigned int *available)
768 return __rte_ring_do_dequeue(r, obj_table, n, RTE_RING_QUEUE_FIXED,
773 * Dequeue several objects from a ring.
775 * This function calls the multi-consumers or the single-consumer
776 * version, depending on the default behaviour that was specified at
777 * ring creation time (see flags).
780 * A pointer to the ring structure.
782 * A pointer to a table of void * pointers (objects) that will be filled.
784 * The number of objects to dequeue from the ring to the obj_table.
786 * If non-NULL, returns the number of remaining ring entries after the
787 * dequeue has finished.
789 * The number of objects dequeued, either 0 or n
791 static __rte_always_inline unsigned int
792 rte_ring_dequeue_bulk(struct rte_ring *r, void **obj_table, unsigned int n,
793 unsigned int *available)
795 return __rte_ring_do_dequeue(r, obj_table, n, RTE_RING_QUEUE_FIXED,
796 r->cons.single, available);
800 * Dequeue one object from a ring (multi-consumers safe).
802 * This function uses a "compare and set" instruction to move the
803 * consumer index atomically.
806 * A pointer to the ring structure.
808 * A pointer to a void * pointer (object) that will be filled.
810 * - 0: Success; objects dequeued.
811 * - -ENOENT: Not enough entries in the ring to dequeue; no object is
814 static __rte_always_inline int
815 rte_ring_mc_dequeue(struct rte_ring *r, void **obj_p)
817 return rte_ring_mc_dequeue_bulk(r, obj_p, 1, NULL) ? 0 : -ENOENT;
821 * Dequeue one object from a ring (NOT multi-consumers safe).
824 * A pointer to the ring structure.
826 * A pointer to a void * pointer (object) that will be filled.
828 * - 0: Success; objects dequeued.
829 * - -ENOENT: Not enough entries in the ring to dequeue, no object is
832 static __rte_always_inline int
833 rte_ring_sc_dequeue(struct rte_ring *r, void **obj_p)
835 return rte_ring_sc_dequeue_bulk(r, obj_p, 1, NULL) ? 0 : -ENOENT;
839 * Dequeue one object from a ring.
841 * This function calls the multi-consumers or the single-consumer
842 * version depending on the default behaviour that was specified at
843 * ring creation time (see flags).
846 * A pointer to the ring structure.
848 * A pointer to a void * pointer (object) that will be filled.
850 * - 0: Success, objects dequeued.
851 * - -ENOENT: Not enough entries in the ring to dequeue, no object is
854 static __rte_always_inline int
855 rte_ring_dequeue(struct rte_ring *r, void **obj_p)
857 return rte_ring_dequeue_bulk(r, obj_p, 1, NULL) ? 0 : -ENOENT;
861 * Return the number of entries in a ring.
864 * A pointer to the ring structure.
866 * The number of entries in the ring.
868 static inline unsigned
869 rte_ring_count(const struct rte_ring *r)
871 uint32_t prod_tail = r->prod.tail;
872 uint32_t cons_tail = r->cons.tail;
873 uint32_t count = (prod_tail - cons_tail) & r->mask;
874 return (count > r->capacity) ? r->capacity : count;
878 * Return the number of free entries in a ring.
881 * A pointer to the ring structure.
883 * The number of free entries in the ring.
885 static inline unsigned
886 rte_ring_free_count(const struct rte_ring *r)
888 return r->capacity - rte_ring_count(r);
892 * Test if a ring is full.
895 * A pointer to the ring structure.
897 * - 1: The ring is full.
898 * - 0: The ring is not full.
901 rte_ring_full(const struct rte_ring *r)
903 return rte_ring_free_count(r) == 0;
907 * Test if a ring is empty.
910 * A pointer to the ring structure.
912 * - 1: The ring is empty.
913 * - 0: The ring is not empty.
916 rte_ring_empty(const struct rte_ring *r)
918 return rte_ring_count(r) == 0;
922 * Return the size of the ring.
925 * A pointer to the ring structure.
927 * The size of the data store used by the ring.
928 * NOTE: this is not the same as the usable space in the ring. To query that
929 * use ``rte_ring_get_capacity()``.
931 static inline unsigned int
932 rte_ring_get_size(const struct rte_ring *r)
938 * Return the number of elements which can be stored in the ring.
941 * A pointer to the ring structure.
943 * The usable size of the ring.
945 static inline unsigned int
946 rte_ring_get_capacity(const struct rte_ring *r)
952 * Dump the status of all rings on the console
955 * A pointer to a file for output
957 void rte_ring_list_dump(FILE *f);
960 * Search a ring from its name
963 * The name of the ring.
965 * The pointer to the ring matching the name, or NULL if not found,
966 * with rte_errno set appropriately. Possible rte_errno values include:
967 * - ENOENT - required entry not available to return.
969 struct rte_ring *rte_ring_lookup(const char *name);
972 * Enqueue several objects on the ring (multi-producers safe).
974 * This function uses a "compare and set" instruction to move the
975 * producer index atomically.
978 * A pointer to the ring structure.
980 * A pointer to a table of void * pointers (objects).
982 * The number of objects to add in the ring from the obj_table.
984 * if non-NULL, returns the amount of space in the ring after the
985 * enqueue operation has finished.
987 * - n: Actual number of objects enqueued.
989 static __rte_always_inline unsigned
990 rte_ring_mp_enqueue_burst(struct rte_ring *r, void * const *obj_table,
991 unsigned int n, unsigned int *free_space)
993 return __rte_ring_do_enqueue(r, obj_table, n,
994 RTE_RING_QUEUE_VARIABLE, __IS_MP, free_space);
998 * Enqueue several objects on a ring (NOT multi-producers safe).
1001 * A pointer to the ring structure.
1003 * A pointer to a table of void * pointers (objects).
1005 * The number of objects to add in the ring from the obj_table.
1007 * if non-NULL, returns the amount of space in the ring after the
1008 * enqueue operation has finished.
1010 * - n: Actual number of objects enqueued.
1012 static __rte_always_inline unsigned
1013 rte_ring_sp_enqueue_burst(struct rte_ring *r, void * const *obj_table,
1014 unsigned int n, unsigned int *free_space)
1016 return __rte_ring_do_enqueue(r, obj_table, n,
1017 RTE_RING_QUEUE_VARIABLE, __IS_SP, free_space);
1021 * Enqueue several objects on a ring.
1023 * This function calls the multi-producer or the single-producer
1024 * version depending on the default behavior that was specified at
1025 * ring creation time (see flags).
1028 * A pointer to the ring structure.
1030 * A pointer to a table of void * pointers (objects).
1032 * The number of objects to add in the ring from the obj_table.
1034 * if non-NULL, returns the amount of space in the ring after the
1035 * enqueue operation has finished.
1037 * - n: Actual number of objects enqueued.
1039 static __rte_always_inline unsigned
1040 rte_ring_enqueue_burst(struct rte_ring *r, void * const *obj_table,
1041 unsigned int n, unsigned int *free_space)
1043 return __rte_ring_do_enqueue(r, obj_table, n, RTE_RING_QUEUE_VARIABLE,
1044 r->prod.single, free_space);
1048 * Dequeue several objects from a ring (multi-consumers safe). When the request
1049 * objects are more than the available objects, only dequeue the actual number
1052 * This function uses a "compare and set" instruction to move the
1053 * consumer index atomically.
1056 * A pointer to the ring structure.
1058 * A pointer to a table of void * pointers (objects) that will be filled.
1060 * The number of objects to dequeue from the ring to the obj_table.
1062 * If non-NULL, returns the number of remaining ring entries after the
1063 * dequeue has finished.
1065 * - n: Actual number of objects dequeued, 0 if ring is empty
1067 static __rte_always_inline unsigned
1068 rte_ring_mc_dequeue_burst(struct rte_ring *r, void **obj_table,
1069 unsigned int n, unsigned int *available)
1071 return __rte_ring_do_dequeue(r, obj_table, n,
1072 RTE_RING_QUEUE_VARIABLE, __IS_MC, available);
1076 * Dequeue several objects from a ring (NOT multi-consumers safe).When the
1077 * request objects are more than the available objects, only dequeue the
1078 * actual number of objects
1081 * A pointer to the ring structure.
1083 * A pointer to a table of void * pointers (objects) that will be filled.
1085 * The number of objects to dequeue from the ring to the obj_table.
1087 * If non-NULL, returns the number of remaining ring entries after the
1088 * dequeue has finished.
1090 * - n: Actual number of objects dequeued, 0 if ring is empty
1092 static __rte_always_inline unsigned
1093 rte_ring_sc_dequeue_burst(struct rte_ring *r, void **obj_table,
1094 unsigned int n, unsigned int *available)
1096 return __rte_ring_do_dequeue(r, obj_table, n,
1097 RTE_RING_QUEUE_VARIABLE, __IS_SC, available);
1101 * Dequeue multiple objects from a ring up to a maximum number.
1103 * This function calls the multi-consumers or the single-consumer
1104 * version, depending on the default behaviour that was specified at
1105 * ring creation time (see flags).
1108 * A pointer to the ring structure.
1110 * A pointer to a table of void * pointers (objects) that will be filled.
1112 * The number of objects to dequeue from the ring to the obj_table.
1114 * If non-NULL, returns the number of remaining ring entries after the
1115 * dequeue has finished.
1117 * - Number of objects dequeued
1119 static __rte_always_inline unsigned
1120 rte_ring_dequeue_burst(struct rte_ring *r, void **obj_table,
1121 unsigned int n, unsigned int *available)
1123 return __rte_ring_do_dequeue(r, obj_table, n,
1124 RTE_RING_QUEUE_VARIABLE,
1125 r->cons.single, available);
1132 #endif /* _RTE_RING_H_ */