2 * Copyright (c) 2016-2019 Cisco and/or its affiliates.
3 * Copyright (c) 2019 Arm Limited
4 * Copyright (c) 2010-2017 Intel Corporation and/or its affiliates.
5 * Copyright (c) 2007-2009 Kip Macy kmacy@freebsd.org
6 * Inspired from DPDK rte_ring.h (SPSC only) (derived from freebsd bufring.h).
7 * Licensed under the Apache License, Version 2.0 (the "License");
8 * you may not use this file except in compliance with the License.
9 * You may obtain a copy of the License at:
11 * http://www.apache.org/licenses/LICENSE-2.0
13 * Unless required by applicable law or agreed to in writing, software
14 * distributed under the License is distributed on an "AS IS" BASIS,
15 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
16 * See the License for the specific language governing permissions and
17 * limitations under the License.
19 #ifndef __included_ssvm_fifo_h__
20 #define __included_ssvm_fifo_h__
22 #include <vppinfra/clib.h>
23 #include <vppinfra/vec.h>
24 #include <vppinfra/pool.h>
25 #include <vppinfra/format.h>
26 #include <vppinfra/rbtree.h>
28 /** Out-of-order segment */
31 u32 next; /**< Next linked-list element pool index */
32 u32 prev; /**< Previous linked-list element pool index */
33 u32 start; /**< Start of segment, normalized*/
34 u32 length; /**< Length of segment */
37 #define SVM_FIFO_TRACE (0)
38 #define OOO_SEGMENT_INVALID_INDEX ((u32)~0)
39 #define SVM_FIFO_INVALID_SESSION_INDEX ((u32)~0)
40 #define SVM_FIFO_INVALID_INDEX ((u32)~0)
41 #define SVM_FIFO_MAX_EVT_SUBSCRIBERS 7
43 typedef enum svm_fifo_deq_ntf_
45 SVM_FIFO_NO_DEQ_NOTIF = 0, /**< No notification requested */
46 SVM_FIFO_WANT_DEQ_NOTIF = 1, /**< Notify on dequeue */
47 SVM_FIFO_WANT_DEQ_NOTIF_IF_FULL = 2, /**< Notify on transition from full */
48 SVM_FIFO_WANT_DEQ_NOTIF_IF_EMPTY = 4, /**< Notify on transition to empty */
56 } svm_fifo_trace_elem_t;
58 typedef struct svm_fifo_chunk_
60 u32 start_byte; /**< chunk start byte */
61 u32 length; /**< length of chunk in bytes */
62 struct svm_fifo_chunk_ *next; /**< pointer to next chunk in linked-lists */
63 u8 data[0]; /**< start of chunk data */
66 typedef enum svm_fifo_flag_
68 SVM_FIFO_F_MULTI_CHUNK = 1 << 0,
69 SVM_FIFO_F_GROW = 1 << 1,
70 SVM_FIFO_F_SHRINK = 1 << 2,
71 SVM_FIFO_F_COLLECT_CHUNKS = 1 << 3,
72 SVM_FIFO_F_LL_TRACKED = 1 << 4,
73 SVM_FIFO_F_SINGLE_THREAD_OWNED = 1 << 5,
76 typedef struct _svm_fifo
78 CLIB_CACHE_LINE_ALIGN_MARK (shared_first);
79 u32 size; /**< size of the fifo in bytes */
80 u32 nitems; /**< usable size (size-1) */
81 u8 flags; /**< fifo flags */
82 svm_fifo_chunk_t *start_chunk;/**< first chunk in fifo chunk list */
83 svm_fifo_chunk_t *end_chunk; /**< end chunk in fifo chunk list */
84 svm_fifo_chunk_t *new_chunks; /**< chunks yet to be added to list */
85 rb_tree_t chunk_lookup;
87 CLIB_CACHE_LINE_ALIGN_MARK (shared_second);
88 volatile u32 has_event; /**< non-zero if deq event exists */
89 u32 master_session_index; /**< session layer session index */
90 u32 client_session_index; /**< app session index */
91 u8 master_thread_index; /**< session layer thread index */
92 u8 client_thread_index; /**< app worker index */
93 i8 refcnt; /**< reference count */
94 u32 segment_manager; /**< session layer segment manager index */
95 u32 segment_index; /**< segment index in segment manager */
96 struct _svm_fifo *next; /**< next in freelist/active chain */
97 struct _svm_fifo *prev; /**< prev in active chain */
98 u32 size_decrement; /**< bytes to remove from fifo */
100 CLIB_CACHE_LINE_ALIGN_MARK (consumer);
101 u32 head; /**< fifo head position/byte */
102 svm_fifo_chunk_t *head_chunk; /**< tracks chunk where head lands */
103 svm_fifo_chunk_t *ooo_deq; /**< last chunk used for ooo dequeue */
104 volatile u32 want_deq_ntf; /**< producer wants nudge */
105 volatile u32 has_deq_ntf;
107 CLIB_CACHE_LINE_ALIGN_MARK (producer);
108 u32 tail; /**< fifo tail position/byte */
109 u32 ooos_list_head; /**< Head of out-of-order linked-list */
110 svm_fifo_chunk_t *tail_chunk; /**< tracks chunk where tail lands */
111 svm_fifo_chunk_t *ooo_enq; /**< last chunk used for ooo enqueue */
112 ooo_segment_t *ooo_segments; /**< Pool of ooo segments */
113 u32 ooos_newest; /**< Last segment to have been updated */
114 volatile u8 n_subscribers; /**< Number of subscribers for io events */
115 u8 subscribers[SVM_FIFO_MAX_EVT_SUBSCRIBERS];
118 svm_fifo_trace_elem_t *trace;
126 SVM_FIFO_EEMPTY = -3,
129 typedef struct svm_fifo_seg_
136 #define svm_fifo_trace_add(_f, _s, _l, _t) \
138 svm_fifo_trace_elem_t *trace_elt; \
139 vec_add2(_f->trace, trace_elt, 1); \
140 trace_elt->offset = _s; \
141 trace_elt->len = _l; \
142 trace_elt->action = _t; \
145 #define svm_fifo_trace_add(_f, _s, _l, _t)
148 u8 *svm_fifo_dump_trace (u8 * s, svm_fifo_t * f);
149 u8 *svm_fifo_replay (u8 * s, svm_fifo_t * f, u8 no_read, u8 verbose);
152 * Load head and tail optimized for consumer
157 f_load_head_tail_cons (svm_fifo_t * f, u32 * head, u32 * tail)
159 /* load-relaxed: consumer owned index */
161 /* load-acq: consumer foreign index (paired with store-rel in producer) */
162 *tail = clib_atomic_load_acq_n (&f->tail);
165 /** Load head and tail optimized for producer
170 f_load_head_tail_prod (svm_fifo_t * f, u32 * head, u32 * tail)
172 /* load relaxed: producer owned index */
174 /* load-acq: producer foreign index (paired with store-rel in consumer) */
175 *head = clib_atomic_load_acq_n (&f->head);
179 * Load head and tail independent of producer/consumer role
184 f_load_head_tail_all_acq (svm_fifo_t * f, u32 * head, u32 * tail)
186 /* load-acq : consumer foreign index (paired with store-rel) */
187 *tail = clib_atomic_load_acq_n (&f->tail);
188 /* load-acq : producer foriegn index (paired with store-rel) */
189 *head = clib_atomic_load_acq_n (&f->head);
193 * Distance to a from b, i.e., a - b in the fifo
198 f_distance_to (svm_fifo_t * f, u32 a, u32 b)
200 return ((f->size + a - b) % f->size);
204 * Distance from a to b, i.e., b - a in the fifo
209 f_distance_from (svm_fifo_t * f, u32 a, u32 b)
211 return ((f->size + b - a) % f->size);
215 * Fifo current size, i.e., number of bytes enqueued
220 f_cursize (svm_fifo_t * f, u32 head, u32 tail)
222 return (head <= tail ? tail - head : f->size + tail - head);
226 * Fifo free bytes, i.e., number of free bytes
231 f_free_count (svm_fifo_t * f, u32 head, u32 tail)
233 return (f->nitems - f_cursize (f, head, tail));
237 * Try to shrink fifo size.
241 void svm_fifo_try_shrink (svm_fifo_t * f, u32 head, u32 tail);
244 * Create fifo of requested size
246 * Allocates fifo on current heap.
248 * @param size data size in bytes for fifo to be allocated. Will be
249 * rounded to the next highest power-of-two value.
250 * @return pointer to new fifo
252 svm_fifo_t *svm_fifo_create (u32 size);
257 * @param size size for fifo
259 void svm_fifo_init (svm_fifo_t * f, u32 size);
261 * Initialize fifo chunks and rbtree
265 void svm_fifo_init_chunks (svm_fifo_t * f);
267 * Allocate a fifo chunk on heap
269 * If the chunk is allocated on a fifo segment, this should be called
270 * with the segment's heap pushed.
272 * @param size chunk size in bytes. Will be rounded to the next highest
274 * @return new chunk or 0 if alloc failed
276 svm_fifo_chunk_t *svm_fifo_chunk_alloc (u32 size);
278 * Grow fifo size by adding chunk to chunk list
280 * If fifos are allocated on a segment, this should be called with
281 * the segment's heap pushed.
283 * @param f fifo to be extended
284 * @param c chunk or linked list of chunks to be added
286 void svm_fifo_add_chunk (svm_fifo_t * f, svm_fifo_chunk_t * c);
288 * Request to reduce fifo size by amount of bytes
290 * Because the producer might be enqueuing data when this is called, the
291 * actual size update is only applied when producer tries to enqueue new
292 * data, unless @param try_shrink is set.
295 * @param len number of bytes to remove from fifo. The actual number
296 * of bytes to be removed will be less or equal to this
298 * @param try_shrink flg to indicate if it's safe to try to shrink fifo
299 * size. It should be set only if this is called by the
300 * producer of if the producer is not using the fifo
301 * @return actual length fifo size will be reduced by
303 int svm_fifo_reduce_size (svm_fifo_t * f, u32 len, u8 try_shrink);
305 * Removes chunks that are after fifo end byte
307 * Needs to be called with segment heap pushed.
311 svm_fifo_chunk_t *svm_fifo_collect_chunks (svm_fifo_t * f);
313 * Free fifo and associated state
317 void svm_fifo_free (svm_fifo_t * f);
319 * Cleanup fifo chunk lookup rb tree
321 * The rb tree is allocated in segment heap so this should be called
324 * @param f fifo to cleanup
326 void svm_fifo_free_chunk_lookup (svm_fifo_t * f);
328 * Cleanup fifo ooo data
330 * The ooo data is allocated in producer process memory. The fifo
331 * segment heap should not be pushed.
333 * @param f fifo to cleanup
335 void svm_fifo_free_ooo_data (svm_fifo_t * f);
337 * Init fifo head and tail
340 * @param head head value that will be matched to a chunk
341 * @param tail tail value that will be matched to a chunk
343 void svm_fifo_init_pointers (svm_fifo_t * f, u32 head, u32 tail);
347 * Clones single/default chunk fifo. It does not work for fifos with
350 void svm_fifo_clone (svm_fifo_t * df, svm_fifo_t * sf);
352 * Enqueue data to fifo
354 * Data is enqueued and tail pointer is updated atomically. If the new data
355 * enqueued partly overlaps or "touches" an out-of-order segment, said segment
356 * is "consumed" and the number of bytes returned is appropriately updated.
359 * @param len length of data to copy
360 * @param src buffer from where to copy the data
361 * @return number of contiguous bytes that can be consumed or error
363 int svm_fifo_enqueue (svm_fifo_t * f, u32 len, const u8 * src);
365 * Enqueue data to fifo with offset
367 * Data is enqueued without updating tail pointer. Instead, an out-of-order
368 * list of segments is generated and maintained. Fifo takes care of coalescing
369 * contiguous or overlapping segments.
372 * @param offset offset at which to copy the data
373 * @param len len of data to copy
374 * @param src buffer from where to copy the data
375 * @return 0 if enqueue was successful, error otherwise
377 int svm_fifo_enqueue_with_offset (svm_fifo_t * f, u32 offset, u32 len,
381 * Advance tail pointer
383 * Useful for moving tail pointer after external enqueue.
386 * @param len number of bytes to add to tail
388 void svm_fifo_enqueue_nocopy (svm_fifo_t * f, u32 len);
390 * Overwrite fifo head with new data
392 * This should be typically used by dgram transport protocols that need
393 * to update the dgram header after dequeueing a chunk of data. It assumes
394 * that the dgram header is at most spread over two chunks.
397 * @param src src of new data
398 * @param len length of new data
400 void svm_fifo_overwrite_head (svm_fifo_t * f, u8 * src, u32 len);
402 * Dequeue data from fifo
404 * Data is dequeued to consumer provided buffer and head is atomically
408 * @param len length of data to dequeue
409 * @param dst buffer to where to dequeue the data
410 * @return number of bytes dequeued or error
412 int svm_fifo_dequeue (svm_fifo_t * f, u32 len, u8 * dst);
414 * Peek data from fifo
416 * Data is copied from requested offset into provided dst buffer. Head is
420 * @param offset offset from which to copy the data
421 * @param len length of data to copy
422 * @param dst buffer to where to dequeue the data
423 * @return number of bytes peeked
425 int svm_fifo_peek (svm_fifo_t * f, u32 offset, u32 len, u8 * dst);
427 * Dequeue and drop bytes from fifo
429 * Advances fifo head by requested amount of bytes.
432 * @param len number of bytes to drop
433 * @return number of bytes dropped
435 int svm_fifo_dequeue_drop (svm_fifo_t * f, u32 len);
437 * Dequeue and drop all bytes from fifo
439 * Advances head to tail position.
443 void svm_fifo_dequeue_drop_all (svm_fifo_t * f);
444 int svm_fifo_segments (svm_fifo_t * f, svm_fifo_seg_t * fs);
445 void svm_fifo_segments_free (svm_fifo_t * f, svm_fifo_seg_t * fs);
447 * Add io events subscriber to list
450 * @param sub subscriber opaque index (typically app worker index)
452 void svm_fifo_add_subscriber (svm_fifo_t * f, u8 sub);
454 * Remove io events subscriber form list
457 * @param sub subscriber index to be removed
459 void svm_fifo_del_subscriber (svm_fifo_t * f, u8 subscriber);
461 * Number of out-of-order segments for fifo
464 * @return number of out of order segments
466 u32 svm_fifo_n_ooo_segments (svm_fifo_t * f);
468 * First out-of-order segment for fifo
471 * @return first out-of-order segment for fifo
473 ooo_segment_t *svm_fifo_first_ooo_segment (svm_fifo_t * f);
475 * Check if fifo is sane. Debug only.
478 * @return 1 if sane, 0 otherwise
480 u8 svm_fifo_is_sane (svm_fifo_t * f);
482 * Declare this fifo is used by only a single thread.
483 * In this special case, fifo-growth can be done in an efficient way without delay.
486 * @return 1 if the fifo is already owned by another thread, 0 otherwise
488 u8 svm_fifo_set_single_thread_owned (svm_fifo_t * f);
489 format_function_t format_svm_fifo;
492 * Fifo max bytes to dequeue optimized for consumer
495 * @return max number of bytes that can be dequeued
498 svm_fifo_max_dequeue_cons (svm_fifo_t * f)
501 f_load_head_tail_cons (f, &head, &tail);
502 return f_cursize (f, head, tail);
506 * Fifo max bytes to dequeue optimized for producer
509 * @return max number of bytes that can be dequeued
512 svm_fifo_max_dequeue_prod (svm_fifo_t * f)
515 f_load_head_tail_prod (f, &head, &tail);
516 return f_cursize (f, head, tail);
520 * Fifo max bytes to dequeue
522 * Note: use producer or consumer specific functions for performance:
523 * @ref svm_fifo_max_dequeue_cons (svm_fifo_t *f)
524 * @ref svm_fifo_max_dequeue_prod (svm_fifo_t *f)
527 svm_fifo_max_dequeue (svm_fifo_t * f)
530 f_load_head_tail_all_acq (f, &head, &tail);
531 return f_cursize (f, head, tail);
535 * Check if fifo is full optimized for producer
538 * @return 1 if fifo is full 0 otherwise
541 svm_fifo_is_full_prod (svm_fifo_t * f)
543 return (svm_fifo_max_dequeue_prod (f) == f->nitems);
546 /* Check if fifo is full.
548 * Note: use producer or consumer specific functions for performance.
549 * @ref svm_fifo_is_full_prod (svm_fifo_t * f)
550 * add cons version if needed
553 svm_fifo_is_full (svm_fifo_t * f)
555 return (svm_fifo_max_dequeue (f) == f->nitems);
559 * Check if fifo is empty optimized for consumer
562 * @return 1 if fifo is empty 0 otherwise
565 svm_fifo_is_empty_cons (svm_fifo_t * f)
567 return (svm_fifo_max_dequeue_cons (f) == 0);
571 * Check if fifo is empty optimized for producer
574 * @return 1 if fifo is empty 0 otherwise
577 svm_fifo_is_empty_prod (svm_fifo_t * f)
579 return (svm_fifo_max_dequeue_prod (f) == 0);
583 * Check if fifo is empty
585 * Note: use producer or consumer specific functions for perfomance.
586 * @ref svm_fifo_is_empty_cons (svm_fifo_t * f)
587 * @ref svm_fifo_is_empty_prod (svm_fifo_t * f)
590 svm_fifo_is_empty (svm_fifo_t * f)
592 return (svm_fifo_max_dequeue (f) == 0);
596 * Check if fifo is wrapped
599 * @return 1 if 'normalized' head is ahead of tail
602 svm_fifo_is_wrapped (svm_fifo_t * f)
605 f_load_head_tail_all_acq (f, &head, &tail);
610 * Maximum number of bytes that can be enqueued into fifo
612 * Optimized for producer
615 * @return max number of bytes that can be enqueued into fifo
618 svm_fifo_max_enqueue_prod (svm_fifo_t * f)
621 f_load_head_tail_prod (f, &head, &tail);
622 if (PREDICT_FALSE (f->flags & SVM_FIFO_F_SHRINK))
623 svm_fifo_try_shrink (f, head, tail);
624 return f_free_count (f, head, tail);
627 /* Maximum number of bytes that can be enqueued into fifo
629 * Note: use producer or consumer specific functions for performance.
630 * @ref svm_fifo_max_enqueue_prod (svm_fifo_t *f)
631 * add consumer specific version if needed.
634 svm_fifo_max_enqueue (svm_fifo_t * f)
637 f_load_head_tail_all_acq (f, &head, &tail);
638 if (PREDICT_FALSE (f->flags & SVM_FIFO_F_SHRINK))
639 svm_fifo_try_shrink (f, head, tail);
640 return f_free_count (f, head, tail);
644 * Max contiguous chunk of data that can be read
647 svm_fifo_max_read_chunk (svm_fifo_t * f)
650 f_load_head_tail_cons (f, &head, &tail);
651 return tail >= head ? (tail - head) : (f->size - head);
655 * Max contiguous chunk of data that can be written
658 svm_fifo_max_write_chunk (svm_fifo_t * f)
661 f_load_head_tail_prod (f, &head, &tail);
662 return tail >= head ? f->size - tail : f_free_count (f, head, tail);
666 svm_fifo_head (svm_fifo_t * f)
668 /* load-relaxed: consumer owned index */
669 return (f->head_chunk->data + (f->head - f->head_chunk->start_byte));
673 svm_fifo_tail (svm_fifo_t * f)
675 /* load-relaxed: producer owned index */
676 return (f->tail_chunk->data + (f->tail - f->tail_chunk->start_byte));
680 svm_fifo_n_subscribers (svm_fifo_t * f)
682 return f->n_subscribers;
686 * Check if fifo has out-of-order data
689 * @return 1 if fifo has ooo data, 0 otherwise
692 svm_fifo_has_ooo_data (svm_fifo_t * f)
694 return f->ooos_list_head != OOO_SEGMENT_INVALID_INDEX;
697 static inline ooo_segment_t *
698 svm_fifo_newest_ooo_segment (svm_fifo_t * f)
700 if (f->ooos_newest == OOO_SEGMENT_INVALID_INDEX)
702 return pool_elt_at_index (f->ooo_segments, f->ooos_newest);
706 svm_fifo_newest_ooo_segment_reset (svm_fifo_t * f)
708 f->ooos_newest = OOO_SEGMENT_INVALID_INDEX;
712 ooo_segment_offset_prod (svm_fifo_t * f, ooo_segment_t * s)
715 /* load-relaxed: producer owned index */
718 return f_distance_to (f, s->start, tail);
722 ooo_segment_length (svm_fifo_t * f, ooo_segment_t * s)
728 * Check if fifo has io event
731 * @return 1 if fifo has event, 0 otherwise
734 svm_fifo_has_event (svm_fifo_t * f)
740 * Set fifo event flag.
742 * Forces release semantics.
745 * @return 1 if flag was not set, 0 otherwise
748 svm_fifo_set_event (svm_fifo_t * f)
750 return !clib_atomic_swap_rel_n (&f->has_event, 1);
754 * Unset fifo event flag.
756 * Forces acquire semantics
761 svm_fifo_unset_event (svm_fifo_t * f)
763 clib_atomic_swap_acq_n (&f->has_event, 0);
767 * Set specific want notification flag
769 * For list of flags see @ref svm_fifo_deq_ntf_t
772 * @param ntf_type type of notification requested
775 svm_fifo_add_want_deq_ntf (svm_fifo_t * f, u8 ntf_type)
777 f->want_deq_ntf |= ntf_type;
781 * Clear specific want notification flag
783 * For list of flags see @ref svm_fifo_ntf_t
786 * @param ntf_type type of notification to be cleared
789 svm_fifo_del_want_deq_ntf (svm_fifo_t * f, u8 ntf_type)
791 f->want_deq_ntf &= ~ntf_type;
795 * Clear the want notification flag and set has notification
797 * Should be used after enqueuing an event. This clears the
798 * SVM_FIFO_WANT_NOTIF flag but it does not clear
799 * SVM_FIFO_WANT_NOTIF_IF_FULL. If the latter was set, has_ntf is
800 * set to avoid enqueueing events for for all dequeue operations until
801 * it is manually cleared.
806 svm_fifo_clear_deq_ntf (svm_fifo_t * f)
808 /* Set the flag if want_notif_if_full was the only ntf requested */
809 f->has_deq_ntf = f->want_deq_ntf == SVM_FIFO_WANT_DEQ_NOTIF_IF_FULL;
810 svm_fifo_del_want_deq_ntf (f, SVM_FIFO_WANT_DEQ_NOTIF);
814 * Clear has notification flag
816 * The fifo generates only one event per SVM_FIFO_WANT_NOTIF_IF_FULL
817 * request and sets has_ntf. To received new events the flag must be
818 * cleared using this function.
823 svm_fifo_reset_has_deq_ntf (svm_fifo_t * f)
829 * Check if fifo needs dequeue notification
831 * Determines based on notification request flags and state of the fifo if
832 * an event should be generated.
835 * @param n_last_deq number of bytes last dequeued
836 * @return 1 if event should be generated, 0 otherwise
839 svm_fifo_needs_deq_ntf (svm_fifo_t * f, u32 n_last_deq)
841 u8 want_ntf = f->want_deq_ntf;
843 if (PREDICT_TRUE (want_ntf == SVM_FIFO_NO_DEQ_NOTIF))
845 else if (want_ntf & SVM_FIFO_WANT_DEQ_NOTIF)
847 if (want_ntf & SVM_FIFO_WANT_DEQ_NOTIF_IF_FULL)
849 u32 max_deq = svm_fifo_max_dequeue_cons (f);
850 u32 nitems = f->nitems;
851 if (!f->has_deq_ntf && max_deq < nitems
852 && max_deq + n_last_deq >= nitems)
855 if (want_ntf & SVM_FIFO_WANT_DEQ_NOTIF_IF_EMPTY)
857 if (!f->has_deq_ntf && svm_fifo_is_empty (f))
863 #endif /* __included_ssvm_fifo_h__ */
866 * fd.io coding-style-patch-verification: ON
869 * eval: (c-set-style "gnu")