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 svm_fifo_chunk_t *start_chunk;/**< first chunk in fifo chunk list */
82 svm_fifo_chunk_t *end_chunk; /**< end chunk in fifo chunk list */
83 svm_fifo_chunk_t *new_chunks; /**< chunks yet to be added to list */
84 rb_tree_t chunk_lookup; /**< rbtree for chunk lookup */
85 u8 flags; /**< fifo flags */
86 u8 slice_index; /**< segment slice for fifo */
88 CLIB_CACHE_LINE_ALIGN_MARK (shared_second);
89 volatile u32 has_event; /**< non-zero if deq event exists */
90 u32 master_session_index; /**< session layer session index */
91 u32 client_session_index; /**< app session index */
92 u8 master_thread_index; /**< session layer thread index */
93 u8 client_thread_index; /**< app worker index */
94 i8 refcnt; /**< reference count */
95 u32 segment_manager; /**< session layer segment manager index */
96 u32 segment_index; /**< segment index in segment manager */
97 struct _svm_fifo *next; /**< next in freelist/active chain */
98 struct _svm_fifo *prev; /**< prev in active chain */
99 u32 size_decrement; /**< bytes to remove from fifo */
101 CLIB_CACHE_LINE_ALIGN_MARK (consumer);
102 u32 head; /**< fifo head position/byte */
103 svm_fifo_chunk_t *head_chunk; /**< tracks chunk where head lands */
104 svm_fifo_chunk_t *ooo_deq; /**< last chunk used for ooo dequeue */
105 volatile u32 want_deq_ntf; /**< producer wants nudge */
106 volatile u32 has_deq_ntf;
108 CLIB_CACHE_LINE_ALIGN_MARK (producer);
109 u32 tail; /**< fifo tail position/byte */
110 u32 ooos_list_head; /**< Head of out-of-order linked-list */
111 svm_fifo_chunk_t *tail_chunk; /**< tracks chunk where tail lands */
112 svm_fifo_chunk_t *ooo_enq; /**< last chunk used for ooo enqueue */
113 ooo_segment_t *ooo_segments; /**< Pool of ooo segments */
114 u32 ooos_newest; /**< Last segment to have been updated */
115 volatile u8 n_subscribers; /**< Number of subscribers for io events */
116 u8 subscribers[SVM_FIFO_MAX_EVT_SUBSCRIBERS];
119 svm_fifo_trace_elem_t *trace;
127 SVM_FIFO_EEMPTY = -3,
130 typedef struct svm_fifo_seg_
137 #define svm_fifo_trace_add(_f, _s, _l, _t) \
139 svm_fifo_trace_elem_t *trace_elt; \
140 vec_add2(_f->trace, trace_elt, 1); \
141 trace_elt->offset = _s; \
142 trace_elt->len = _l; \
143 trace_elt->action = _t; \
146 #define svm_fifo_trace_add(_f, _s, _l, _t)
149 u8 *svm_fifo_dump_trace (u8 * s, svm_fifo_t * f);
150 u8 *svm_fifo_replay (u8 * s, svm_fifo_t * f, u8 no_read, u8 verbose);
153 * Load head and tail optimized for consumer
158 f_load_head_tail_cons (svm_fifo_t * f, u32 * head, u32 * tail)
160 /* load-relaxed: consumer owned index */
162 /* load-acq: consumer foreign index (paired with store-rel in producer) */
163 *tail = clib_atomic_load_acq_n (&f->tail);
166 /** Load head and tail optimized for producer
171 f_load_head_tail_prod (svm_fifo_t * f, u32 * head, u32 * tail)
173 /* load relaxed: producer owned index */
175 /* load-acq: producer foreign index (paired with store-rel in consumer) */
176 *head = clib_atomic_load_acq_n (&f->head);
180 * Load head and tail independent of producer/consumer role
185 f_load_head_tail_all_acq (svm_fifo_t * f, u32 * head, u32 * tail)
187 /* load-acq : consumer foreign index (paired with store-rel) */
188 *tail = clib_atomic_load_acq_n (&f->tail);
189 /* load-acq : producer foriegn index (paired with store-rel) */
190 *head = clib_atomic_load_acq_n (&f->head);
194 * Distance to a from b, i.e., a - b in the fifo
199 f_distance_to (svm_fifo_t * f, u32 a, u32 b)
201 return ((f->size + a - b) % f->size);
205 * Distance from a to b, i.e., b - a in the fifo
210 f_distance_from (svm_fifo_t * f, u32 a, u32 b)
212 return ((f->size + b - a) % f->size);
216 * Fifo current size, i.e., number of bytes enqueued
221 f_cursize (svm_fifo_t * f, u32 head, u32 tail)
223 return (head <= tail ? tail - head : f->size + tail - head);
227 * Fifo free bytes, i.e., number of free bytes
232 f_free_count (svm_fifo_t * f, u32 head, u32 tail)
234 return (f->nitems - f_cursize (f, head, tail));
238 * Try to shrink fifo size.
242 void svm_fifo_try_shrink (svm_fifo_t * f, u32 head, u32 tail);
245 * Create fifo of requested size
247 * Allocates fifo on current heap.
249 * @param size data size in bytes for fifo to be allocated. Will be
250 * rounded to the next highest power-of-two value.
251 * @return pointer to new fifo
253 svm_fifo_t *svm_fifo_create (u32 size);
258 * @param size size for fifo
260 void svm_fifo_init (svm_fifo_t * f, u32 size);
262 * Initialize fifo chunks and rbtree
266 void svm_fifo_init_chunks (svm_fifo_t * f);
268 * Allocate a fifo chunk on heap
270 * If the chunk is allocated on a fifo segment, this should be called
271 * with the segment's heap pushed.
273 * @param size chunk size in bytes. Will be rounded to the next highest
275 * @return new chunk or 0 if alloc failed
277 svm_fifo_chunk_t *svm_fifo_chunk_alloc (u32 size);
279 * Grow fifo size by adding chunk to chunk list
281 * If fifos are allocated on a segment, this should be called with
282 * the segment's heap pushed.
284 * @param f fifo to be extended
285 * @param c chunk or linked list of chunks to be added
287 void svm_fifo_add_chunk (svm_fifo_t * f, svm_fifo_chunk_t * c);
289 * Request to reduce fifo size by amount of bytes
291 * Because the producer might be enqueuing data when this is called, the
292 * actual size update is only applied when producer tries to enqueue new
293 * data, unless @param try_shrink is set.
296 * @param len number of bytes to remove from fifo. The actual number
297 * of bytes to be removed will be less or equal to this
299 * @param try_shrink flg to indicate if it's safe to try to shrink fifo
300 * size. It should be set only if this is called by the
301 * producer of if the producer is not using the fifo
302 * @return actual length fifo size will be reduced by
304 int svm_fifo_reduce_size (svm_fifo_t * f, u32 len, u8 try_shrink);
306 * Removes chunks that are after fifo end byte
308 * Needs to be called with segment heap pushed.
312 svm_fifo_chunk_t *svm_fifo_collect_chunks (svm_fifo_t * f);
314 * Free fifo and associated state
318 void svm_fifo_free (svm_fifo_t * f);
320 * Cleanup fifo chunk lookup rb tree
322 * The rb tree is allocated in segment heap so this should be called
325 * @param f fifo to cleanup
327 void svm_fifo_free_chunk_lookup (svm_fifo_t * f);
329 * Cleanup fifo ooo data
331 * The ooo data is allocated in producer process memory. The fifo
332 * segment heap should not be pushed.
334 * @param f fifo to cleanup
336 void svm_fifo_free_ooo_data (svm_fifo_t * f);
338 * Init fifo head and tail
341 * @param head head value that will be matched to a chunk
342 * @param tail tail value that will be matched to a chunk
344 void svm_fifo_init_pointers (svm_fifo_t * f, u32 head, u32 tail);
348 * Clones single/default chunk fifo. It does not work for fifos with
351 void svm_fifo_clone (svm_fifo_t * df, svm_fifo_t * sf);
353 * Enqueue data to fifo
355 * Data is enqueued and tail pointer is updated atomically. If the new data
356 * enqueued partly overlaps or "touches" an out-of-order segment, said segment
357 * is "consumed" and the number of bytes returned is appropriately updated.
360 * @param len length of data to copy
361 * @param src buffer from where to copy the data
362 * @return number of contiguous bytes that can be consumed or error
364 int svm_fifo_enqueue (svm_fifo_t * f, u32 len, const u8 * src);
366 * Enqueue data to fifo with offset
368 * Data is enqueued without updating tail pointer. Instead, an out-of-order
369 * list of segments is generated and maintained. Fifo takes care of coalescing
370 * contiguous or overlapping segments.
373 * @param offset offset at which to copy the data
374 * @param len len of data to copy
375 * @param src buffer from where to copy the data
376 * @return 0 if enqueue was successful, error otherwise
378 int svm_fifo_enqueue_with_offset (svm_fifo_t * f, u32 offset, u32 len,
382 * Advance tail pointer
384 * Useful for moving tail pointer after external enqueue.
387 * @param len number of bytes to add to tail
389 void svm_fifo_enqueue_nocopy (svm_fifo_t * f, u32 len);
391 * Overwrite fifo head with new data
393 * This should be typically used by dgram transport protocols that need
394 * to update the dgram header after dequeueing a chunk of data. It assumes
395 * that the dgram header is at most spread over two chunks.
398 * @param src src of new data
399 * @param len length of new data
401 void svm_fifo_overwrite_head (svm_fifo_t * f, u8 * src, u32 len);
403 * Dequeue data from fifo
405 * Data is dequeued to consumer provided buffer and head is atomically
409 * @param len length of data to dequeue
410 * @param dst buffer to where to dequeue the data
411 * @return number of bytes dequeued or error
413 int svm_fifo_dequeue (svm_fifo_t * f, u32 len, u8 * dst);
415 * Peek data from fifo
417 * Data is copied from requested offset into provided dst buffer. Head is
421 * @param offset offset from which to copy the data
422 * @param len length of data to copy
423 * @param dst buffer to where to dequeue the data
424 * @return number of bytes peeked
426 int svm_fifo_peek (svm_fifo_t * f, u32 offset, u32 len, u8 * dst);
428 * Dequeue and drop bytes from fifo
430 * Advances fifo head by requested amount of bytes.
433 * @param len number of bytes to drop
434 * @return number of bytes dropped
436 int svm_fifo_dequeue_drop (svm_fifo_t * f, u32 len);
438 * Dequeue and drop all bytes from fifo
440 * Advances head to tail position.
444 void svm_fifo_dequeue_drop_all (svm_fifo_t * f);
445 int svm_fifo_segments (svm_fifo_t * f, svm_fifo_seg_t * fs);
446 void svm_fifo_segments_free (svm_fifo_t * f, svm_fifo_seg_t * fs);
448 * Add io events subscriber to list
451 * @param sub subscriber opaque index (typically app worker index)
453 void svm_fifo_add_subscriber (svm_fifo_t * f, u8 sub);
455 * Remove io events subscriber form list
458 * @param sub subscriber index to be removed
460 void svm_fifo_del_subscriber (svm_fifo_t * f, u8 subscriber);
462 * Number of out-of-order segments for fifo
465 * @return number of out of order segments
467 u32 svm_fifo_n_ooo_segments (svm_fifo_t * f);
469 * First out-of-order segment for fifo
472 * @return first out-of-order segment for fifo
474 ooo_segment_t *svm_fifo_first_ooo_segment (svm_fifo_t * f);
476 * Check if fifo is sane. Debug only.
479 * @return 1 if sane, 0 otherwise
481 u8 svm_fifo_is_sane (svm_fifo_t * f);
483 * Declare this fifo is used by only a single thread.
484 * In this special case, fifo-growth can be done in an efficient way without delay.
487 * @return 1 if the fifo is already owned by another thread, 0 otherwise
489 u8 svm_fifo_set_single_thread_owned (svm_fifo_t * f);
490 format_function_t format_svm_fifo;
493 * Fifo max bytes to dequeue optimized for consumer
496 * @return max number of bytes that can be dequeued
499 svm_fifo_max_dequeue_cons (svm_fifo_t * f)
502 f_load_head_tail_cons (f, &head, &tail);
503 return f_cursize (f, head, tail);
507 * Fifo max bytes to dequeue optimized for producer
510 * @return max number of bytes that can be dequeued
513 svm_fifo_max_dequeue_prod (svm_fifo_t * f)
516 f_load_head_tail_prod (f, &head, &tail);
517 return f_cursize (f, head, tail);
521 * Fifo max bytes to dequeue
523 * Note: use producer or consumer specific functions for performance:
524 * @ref svm_fifo_max_dequeue_cons (svm_fifo_t *f)
525 * @ref svm_fifo_max_dequeue_prod (svm_fifo_t *f)
528 svm_fifo_max_dequeue (svm_fifo_t * f)
531 f_load_head_tail_all_acq (f, &head, &tail);
532 return f_cursize (f, head, tail);
536 * Check if fifo is full optimized for producer
539 * @return 1 if fifo is full 0 otherwise
542 svm_fifo_is_full_prod (svm_fifo_t * f)
544 return (svm_fifo_max_dequeue_prod (f) == f->nitems);
547 /* Check if fifo is full.
549 * Note: use producer or consumer specific functions for performance.
550 * @ref svm_fifo_is_full_prod (svm_fifo_t * f)
551 * add cons version if needed
554 svm_fifo_is_full (svm_fifo_t * f)
556 return (svm_fifo_max_dequeue (f) == f->nitems);
560 * Check if fifo is empty optimized for consumer
563 * @return 1 if fifo is empty 0 otherwise
566 svm_fifo_is_empty_cons (svm_fifo_t * f)
568 return (svm_fifo_max_dequeue_cons (f) == 0);
572 * Check if fifo is empty optimized for producer
575 * @return 1 if fifo is empty 0 otherwise
578 svm_fifo_is_empty_prod (svm_fifo_t * f)
580 return (svm_fifo_max_dequeue_prod (f) == 0);
584 * Check if fifo is empty
586 * Note: use producer or consumer specific functions for perfomance.
587 * @ref svm_fifo_is_empty_cons (svm_fifo_t * f)
588 * @ref svm_fifo_is_empty_prod (svm_fifo_t * f)
591 svm_fifo_is_empty (svm_fifo_t * f)
593 return (svm_fifo_max_dequeue (f) == 0);
597 * Check if fifo is wrapped
600 * @return 1 if 'normalized' head is ahead of tail
603 svm_fifo_is_wrapped (svm_fifo_t * f)
606 f_load_head_tail_all_acq (f, &head, &tail);
611 * Maximum number of bytes that can be enqueued into fifo
613 * Optimized for producer
616 * @return max number of bytes that can be enqueued into fifo
619 svm_fifo_max_enqueue_prod (svm_fifo_t * f)
622 f_load_head_tail_prod (f, &head, &tail);
623 if (PREDICT_FALSE (f->flags & SVM_FIFO_F_SHRINK))
624 svm_fifo_try_shrink (f, head, tail);
625 return f_free_count (f, head, tail);
628 /* Maximum number of bytes that can be enqueued into fifo
630 * Note: use producer or consumer specific functions for performance.
631 * @ref svm_fifo_max_enqueue_prod (svm_fifo_t *f)
632 * add consumer specific version if needed.
635 svm_fifo_max_enqueue (svm_fifo_t * f)
638 f_load_head_tail_all_acq (f, &head, &tail);
639 if (PREDICT_FALSE (f->flags & SVM_FIFO_F_SHRINK))
640 svm_fifo_try_shrink (f, head, tail);
641 return f_free_count (f, head, tail);
645 * Max contiguous chunk of data that can be read
648 svm_fifo_max_read_chunk (svm_fifo_t * f)
651 f_load_head_tail_cons (f, &head, &tail);
652 return tail >= head ? (tail - head) : (f->size - head);
656 * Max contiguous chunk of data that can be written
659 svm_fifo_max_write_chunk (svm_fifo_t * f)
662 f_load_head_tail_prod (f, &head, &tail);
663 return tail >= head ? f->size - tail : f_free_count (f, head, tail);
667 svm_fifo_head (svm_fifo_t * f)
669 /* load-relaxed: consumer owned index */
670 return (f->head_chunk->data + (f->head - f->head_chunk->start_byte));
674 svm_fifo_tail (svm_fifo_t * f)
676 /* load-relaxed: producer owned index */
677 return (f->tail_chunk->data + (f->tail - f->tail_chunk->start_byte));
681 svm_fifo_n_subscribers (svm_fifo_t * f)
683 return f->n_subscribers;
687 * Check if fifo has out-of-order data
690 * @return 1 if fifo has ooo data, 0 otherwise
693 svm_fifo_has_ooo_data (svm_fifo_t * f)
695 return f->ooos_list_head != OOO_SEGMENT_INVALID_INDEX;
698 static inline ooo_segment_t *
699 svm_fifo_newest_ooo_segment (svm_fifo_t * f)
701 if (f->ooos_newest == OOO_SEGMENT_INVALID_INDEX)
703 return pool_elt_at_index (f->ooo_segments, f->ooos_newest);
707 svm_fifo_newest_ooo_segment_reset (svm_fifo_t * f)
709 f->ooos_newest = OOO_SEGMENT_INVALID_INDEX;
713 ooo_segment_offset_prod (svm_fifo_t * f, ooo_segment_t * s)
716 /* load-relaxed: producer owned index */
719 return f_distance_to (f, s->start, tail);
723 ooo_segment_length (svm_fifo_t * f, ooo_segment_t * s)
729 * Check if fifo has io event
732 * @return 1 if fifo has event, 0 otherwise
735 svm_fifo_has_event (svm_fifo_t * f)
741 * Set fifo event flag.
743 * Forces release semantics.
746 * @return 1 if flag was not set, 0 otherwise
749 svm_fifo_set_event (svm_fifo_t * f)
751 return !clib_atomic_swap_rel_n (&f->has_event, 1);
755 * Unset fifo event flag.
757 * Forces acquire semantics
762 svm_fifo_unset_event (svm_fifo_t * f)
764 clib_atomic_swap_acq_n (&f->has_event, 0);
768 * Set specific want notification flag
770 * For list of flags see @ref svm_fifo_deq_ntf_t
773 * @param ntf_type type of notification requested
776 svm_fifo_add_want_deq_ntf (svm_fifo_t * f, u8 ntf_type)
778 f->want_deq_ntf |= ntf_type;
782 * Clear specific want notification flag
784 * For list of flags see @ref svm_fifo_ntf_t
787 * @param ntf_type type of notification to be cleared
790 svm_fifo_del_want_deq_ntf (svm_fifo_t * f, u8 ntf_type)
792 f->want_deq_ntf &= ~ntf_type;
796 * Clear the want notification flag and set has notification
798 * Should be used after enqueuing an event. This clears the
799 * SVM_FIFO_WANT_NOTIF flag but it does not clear
800 * SVM_FIFO_WANT_NOTIF_IF_FULL. If the latter was set, has_ntf is
801 * set to avoid enqueueing events for for all dequeue operations until
802 * it is manually cleared.
807 svm_fifo_clear_deq_ntf (svm_fifo_t * f)
809 /* Set the flag if want_notif_if_full was the only ntf requested */
810 f->has_deq_ntf = f->want_deq_ntf == SVM_FIFO_WANT_DEQ_NOTIF_IF_FULL;
811 svm_fifo_del_want_deq_ntf (f, SVM_FIFO_WANT_DEQ_NOTIF);
815 * Clear has notification flag
817 * The fifo generates only one event per SVM_FIFO_WANT_NOTIF_IF_FULL
818 * request and sets has_ntf. To received new events the flag must be
819 * cleared using this function.
824 svm_fifo_reset_has_deq_ntf (svm_fifo_t * f)
830 * Check if fifo needs dequeue notification
832 * Determines based on notification request flags and state of the fifo if
833 * an event should be generated.
836 * @param n_last_deq number of bytes last dequeued
837 * @return 1 if event should be generated, 0 otherwise
840 svm_fifo_needs_deq_ntf (svm_fifo_t * f, u32 n_last_deq)
842 u8 want_ntf = f->want_deq_ntf;
844 if (PREDICT_TRUE (want_ntf == SVM_FIFO_NO_DEQ_NOTIF))
846 else if (want_ntf & SVM_FIFO_WANT_DEQ_NOTIF)
848 if (want_ntf & SVM_FIFO_WANT_DEQ_NOTIF_IF_FULL)
850 u32 max_deq = svm_fifo_max_dequeue_cons (f);
851 u32 nitems = f->nitems;
852 if (!f->has_deq_ntf && max_deq < nitems
853 && max_deq + n_last_deq >= nitems)
856 if (want_ntf & SVM_FIFO_WANT_DEQ_NOTIF_IF_EMPTY)
858 if (!f->has_deq_ntf && svm_fifo_is_empty (f))
864 #endif /* __included_ssvm_fifo_h__ */
867 * fd.io coding-style-patch-verification: ON
870 * eval: (c-set-style "gnu")