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,
75 typedef struct _svm_fifo
77 CLIB_CACHE_LINE_ALIGN_MARK (shared_first);
78 u32 size; /**< size of the fifo in bytes */
79 u32 nitems; /**< usable size (size-1) */
80 u8 flags; /**< fifo flags */
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;
86 CLIB_CACHE_LINE_ALIGN_MARK (shared_second);
87 volatile u32 has_event; /**< non-zero if deq event exists */
88 u32 master_session_index; /**< session layer session index */
89 u32 client_session_index; /**< app session index */
90 u8 master_thread_index; /**< session layer thread index */
91 u8 client_thread_index; /**< app worker index */
92 i8 refcnt; /**< reference count */
93 u32 segment_manager; /**< session layer segment manager index */
94 u32 segment_index; /**< segment index in segment manager */
95 struct _svm_fifo *next; /**< next in freelist/active chain */
96 struct _svm_fifo *prev; /**< prev in active chain */
97 u32 size_decrement; /**< bytes to remove from fifo */
99 CLIB_CACHE_LINE_ALIGN_MARK (consumer);
100 u32 head; /**< fifo head position/byte */
101 svm_fifo_chunk_t *head_chunk; /**< tracks chunk where head lands */
102 svm_fifo_chunk_t *ooo_deq; /**< last chunk used for ooo dequeue */
103 volatile u32 want_deq_ntf; /**< producer wants nudge */
104 volatile u32 has_deq_ntf;
106 CLIB_CACHE_LINE_ALIGN_MARK (producer);
107 u32 tail; /**< fifo tail position/byte */
108 u32 ooos_list_head; /**< Head of out-of-order linked-list */
109 svm_fifo_chunk_t *tail_chunk; /**< tracks chunk where tail lands */
110 svm_fifo_chunk_t *ooo_enq; /**< last chunk used for ooo enqueue */
111 ooo_segment_t *ooo_segments; /**< Pool of ooo segments */
112 u32 ooos_newest; /**< Last segment to have been updated */
113 volatile u8 n_subscribers; /**< Number of subscribers for io events */
114 u8 subscribers[SVM_FIFO_MAX_EVT_SUBSCRIBERS];
117 svm_fifo_trace_elem_t *trace;
125 SVM_FIFO_EEMPTY = -3,
128 typedef struct svm_fifo_seg_
135 #define svm_fifo_trace_add(_f, _s, _l, _t) \
137 svm_fifo_trace_elem_t *trace_elt; \
138 vec_add2(_f->trace, trace_elt, 1); \
139 trace_elt->offset = _s; \
140 trace_elt->len = _l; \
141 trace_elt->action = _t; \
144 #define svm_fifo_trace_add(_f, _s, _l, _t)
147 u8 *svm_fifo_dump_trace (u8 * s, svm_fifo_t * f);
148 u8 *svm_fifo_replay (u8 * s, svm_fifo_t * f, u8 no_read, u8 verbose);
151 * Load head and tail optimized for consumer
156 f_load_head_tail_cons (svm_fifo_t * f, u32 * head, u32 * tail)
158 /* load-relaxed: consumer owned index */
160 /* load-acq: consumer foreign index (paired with store-rel in producer) */
161 *tail = clib_atomic_load_acq_n (&f->tail);
164 /** Load head and tail optimized for producer
169 f_load_head_tail_prod (svm_fifo_t * f, u32 * head, u32 * tail)
171 /* load relaxed: producer owned index */
173 /* load-acq: producer foreign index (paired with store-rel in consumer) */
174 *head = clib_atomic_load_acq_n (&f->head);
178 * Load head and tail independent of producer/consumer role
183 f_load_head_tail_all_acq (svm_fifo_t * f, u32 * head, u32 * tail)
185 /* load-acq : consumer foreign index (paired with store-rel) */
186 *tail = clib_atomic_load_acq_n (&f->tail);
187 /* load-acq : producer foriegn index (paired with store-rel) */
188 *head = clib_atomic_load_acq_n (&f->head);
192 * Distance to a from b, i.e., a - b in the fifo
197 f_distance_to (svm_fifo_t * f, u32 a, u32 b)
199 return ((f->size + a - b) % f->size);
203 * Distance from a to b, i.e., b - a in the fifo
208 f_distance_from (svm_fifo_t * f, u32 a, u32 b)
210 return ((f->size + b - a) % f->size);
214 * Fifo current size, i.e., number of bytes enqueued
219 f_cursize (svm_fifo_t * f, u32 head, u32 tail)
221 return (head <= tail ? tail - head : f->size + tail - head);
225 * Fifo free bytes, i.e., number of free bytes
230 f_free_count (svm_fifo_t * f, u32 head, u32 tail)
232 return (f->nitems - f_cursize (f, head, tail));
236 * Try to shrink fifo size.
240 void svm_fifo_try_shrink (svm_fifo_t * f, u32 head, u32 tail);
243 * Create fifo of requested size
245 * Allocates fifo on current heap.
247 * @param size data size in bytes for fifo to be allocated. Will be
248 * rounded to the next highest power-of-two value.
249 * @return pointer to new fifo
251 svm_fifo_t *svm_fifo_create (u32 size);
256 * @param size size for fifo
258 void svm_fifo_init (svm_fifo_t * f, u32 size);
260 * Initialize fifo chunks and rbtree
264 void svm_fifo_init_chunks (svm_fifo_t * f);
266 * Allocate a fifo chunk on heap
268 * If the chunk is allocated on a fifo segment, this should be called
269 * with the segment's heap pushed.
271 * @param size chunk size in bytes. Will be rounded to the next highest
273 * @return new chunk or 0 if alloc failed
275 svm_fifo_chunk_t *svm_fifo_chunk_alloc (u32 size);
277 * Grow fifo size by adding chunk to chunk list
279 * If fifos are allocated on a segment, this should be called with
280 * the segment's heap pushed.
282 * @param f fifo to be extended
283 * @param c chunk or linked list of chunks to be added
285 void svm_fifo_add_chunk (svm_fifo_t * f, svm_fifo_chunk_t * c);
287 * Request to reduce fifo size by amount of bytes
289 * Because the producer might be enqueuing data when this is called, the
290 * actual size update is only applied when producer tries to enqueue new
291 * data, unless @param try_shrink is set.
294 * @param len number of bytes to remove from fifo. The actual number
295 * of bytes to be removed will be less or equal to this
297 * @param try_shrink flg to indicate if it's safe to try to shrink fifo
298 * size. It should be set only if this is called by the
299 * producer of if the producer is not using the fifo
300 * @return actual length fifo size will be reduced by
302 int svm_fifo_reduce_size (svm_fifo_t * f, u32 len, u8 try_shrink);
304 * Removes chunks that are after fifo end byte
306 * Needs to be called with segment heap pushed.
310 svm_fifo_chunk_t *svm_fifo_collect_chunks (svm_fifo_t * f);
312 * Free fifo and associated state
316 void svm_fifo_free (svm_fifo_t * f);
318 * Cleanup fifo chunk lookup rb tree
320 * The rb tree is allocated in segment heap so this should be called
323 * @param f fifo to cleanup
325 void svm_fifo_free_chunk_lookup (svm_fifo_t * f);
327 * Cleanup fifo ooo data
329 * The ooo data is allocated in producer process memory. The fifo
330 * segment heap should not be pushed.
332 * @param f fifo to cleanup
334 void svm_fifo_free_ooo_data (svm_fifo_t * f);
336 * Init fifo head and tail
339 * @param head head value that will be matched to a chunk
340 * @param tail tail value that will be matched to a chunk
342 void svm_fifo_init_pointers (svm_fifo_t * f, u32 head, u32 tail);
346 * Clones single/default chunk fifo. It does not work for fifos with
349 void svm_fifo_clone (svm_fifo_t * df, svm_fifo_t * sf);
351 * Enqueue data to fifo
353 * Data is enqueued and tail pointer is updated atomically. If the new data
354 * enqueued partly overlaps or "touches" an out-of-order segment, said segment
355 * is "consumed" and the number of bytes returned is appropriately updated.
358 * @param len length of data to copy
359 * @param src buffer from where to copy the data
360 * @return number of contiguous bytes that can be consumed or error
362 int svm_fifo_enqueue (svm_fifo_t * f, u32 len, const u8 * src);
364 * Enqueue data to fifo with offset
366 * Data is enqueued without updating tail pointer. Instead, an out-of-order
367 * list of segments is generated and maintained. Fifo takes care of coalescing
368 * contiguous or overlapping segments.
371 * @param offset offset at which to copy the data
372 * @param len len of data to copy
373 * @param src buffer from where to copy the data
374 * @return 0 if enqueue was successful, error otherwise
376 int svm_fifo_enqueue_with_offset (svm_fifo_t * f, u32 offset, u32 len,
380 * Advance tail pointer
382 * Useful for moving tail pointer after external enqueue.
385 * @param len number of bytes to add to tail
387 void svm_fifo_enqueue_nocopy (svm_fifo_t * f, u32 len);
389 * Overwrite fifo head with new data
391 * This should be typically used by dgram transport protocols that need
392 * to update the dgram header after dequeueing a chunk of data. It assumes
393 * that the dgram header is at most spread over two chunks.
396 * @param src src of new data
397 * @param len length of new data
399 void svm_fifo_overwrite_head (svm_fifo_t * f, u8 * src, u32 len);
401 * Dequeue data from fifo
403 * Data is dequeued to consumer provided buffer and head is atomically
407 * @param len length of data to dequeue
408 * @param dst buffer to where to dequeue the data
409 * @return number of bytes dequeued or error
411 int svm_fifo_dequeue (svm_fifo_t * f, u32 len, u8 * dst);
413 * Peek data from fifo
415 * Data is copied from requested offset into provided dst buffer. Head is
419 * @param offset offset from which to copy the data
420 * @param len length of data to copy
421 * @param dst buffer to where to dequeue the data
422 * @return number of bytes peeked
424 int svm_fifo_peek (svm_fifo_t * f, u32 offset, u32 len, u8 * dst);
426 * Dequeue and drop bytes from fifo
428 * Advances fifo head by requested amount of bytes.
431 * @param len number of bytes to drop
432 * @return number of bytes dropped
434 int svm_fifo_dequeue_drop (svm_fifo_t * f, u32 len);
436 * Dequeue and drop all bytes from fifo
438 * Advances head to tail position.
442 void svm_fifo_dequeue_drop_all (svm_fifo_t * f);
443 int svm_fifo_segments (svm_fifo_t * f, svm_fifo_seg_t * fs);
444 void svm_fifo_segments_free (svm_fifo_t * f, svm_fifo_seg_t * fs);
446 * Add io events subscriber to list
449 * @param sub subscriber opaque index (typically app worker index)
451 void svm_fifo_add_subscriber (svm_fifo_t * f, u8 sub);
453 * Remove io events subscriber form list
456 * @param sub subscriber index to be removed
458 void svm_fifo_del_subscriber (svm_fifo_t * f, u8 subscriber);
460 * Number of out-of-order segments for fifo
463 * @return number of out of order segments
465 u32 svm_fifo_n_ooo_segments (svm_fifo_t * f);
467 * First out-of-order segment for fifo
470 * @return first out-of-order segment for fifo
472 ooo_segment_t *svm_fifo_first_ooo_segment (svm_fifo_t * f);
474 * Check if fifo is sane. Debug only.
477 * @return 1 if sane, 0 otherwise
479 u8 svm_fifo_is_sane (svm_fifo_t * f);
480 format_function_t format_svm_fifo;
483 * Fifo max bytes to dequeue optimized for consumer
486 * @return max number of bytes that can be dequeued
489 svm_fifo_max_dequeue_cons (svm_fifo_t * f)
492 f_load_head_tail_cons (f, &head, &tail);
493 return f_cursize (f, head, tail);
497 * Fifo max bytes to dequeue optimized for producer
500 * @return max number of bytes that can be dequeued
503 svm_fifo_max_dequeue_prod (svm_fifo_t * f)
506 f_load_head_tail_prod (f, &head, &tail);
507 return f_cursize (f, head, tail);
511 * Fifo max bytes to dequeue
513 * Note: use producer or consumer specific functions for performance:
514 * @ref svm_fifo_max_dequeue_cons (svm_fifo_t *f)
515 * @ref svm_fifo_max_dequeue_prod (svm_fifo_t *f)
518 svm_fifo_max_dequeue (svm_fifo_t * f)
521 f_load_head_tail_all_acq (f, &head, &tail);
522 return f_cursize (f, head, tail);
526 * Check if fifo is full optimized for producer
529 * @return 1 if fifo is full 0 otherwise
532 svm_fifo_is_full_prod (svm_fifo_t * f)
534 return (svm_fifo_max_dequeue_prod (f) == f->nitems);
537 /* Check if fifo is full.
539 * Note: use producer or consumer specific functions for performance.
540 * @ref svm_fifo_is_full_prod (svm_fifo_t * f)
541 * add cons version if needed
544 svm_fifo_is_full (svm_fifo_t * f)
546 return (svm_fifo_max_dequeue (f) == f->nitems);
550 * Check if fifo is empty optimized for consumer
553 * @return 1 if fifo is empty 0 otherwise
556 svm_fifo_is_empty_cons (svm_fifo_t * f)
558 return (svm_fifo_max_dequeue_cons (f) == 0);
562 * Check if fifo is empty optimized for producer
565 * @return 1 if fifo is empty 0 otherwise
568 svm_fifo_is_empty_prod (svm_fifo_t * f)
570 return (svm_fifo_max_dequeue_prod (f) == 0);
574 * Check if fifo is empty
576 * Note: use producer or consumer specific functions for perfomance.
577 * @ref svm_fifo_is_empty_cons (svm_fifo_t * f)
578 * @ref svm_fifo_is_empty_prod (svm_fifo_t * f)
581 svm_fifo_is_empty (svm_fifo_t * f)
583 return (svm_fifo_max_dequeue (f) == 0);
587 * Check if fifo is wrapped
590 * @return 1 if 'normalized' head is ahead of tail
593 svm_fifo_is_wrapped (svm_fifo_t * f)
596 f_load_head_tail_all_acq (f, &head, &tail);
601 * Maximum number of bytes that can be enqueued into fifo
603 * Optimized for producer
606 * @return max number of bytes that can be enqueued into fifo
609 svm_fifo_max_enqueue_prod (svm_fifo_t * f)
612 f_load_head_tail_prod (f, &head, &tail);
613 if (PREDICT_FALSE (f->flags & SVM_FIFO_F_SHRINK))
614 svm_fifo_try_shrink (f, head, tail);
615 return f_free_count (f, head, tail);
618 /* Maximum number of bytes that can be enqueued into fifo
620 * Note: use producer or consumer specific functions for performance.
621 * @ref svm_fifo_max_enqueue_prod (svm_fifo_t *f)
622 * add consumer specific version if needed.
625 svm_fifo_max_enqueue (svm_fifo_t * f)
628 f_load_head_tail_all_acq (f, &head, &tail);
629 if (PREDICT_FALSE (f->flags & SVM_FIFO_F_SHRINK))
630 svm_fifo_try_shrink (f, head, tail);
631 return f_free_count (f, head, tail);
635 * Max contiguous chunk of data that can be read
638 svm_fifo_max_read_chunk (svm_fifo_t * f)
641 f_load_head_tail_cons (f, &head, &tail);
642 return tail >= head ? (tail - head) : (f->size - head);
646 * Max contiguous chunk of data that can be written
649 svm_fifo_max_write_chunk (svm_fifo_t * f)
652 f_load_head_tail_prod (f, &head, &tail);
653 return tail >= head ? f->size - tail : f_free_count (f, head, tail);
657 svm_fifo_head (svm_fifo_t * f)
659 /* load-relaxed: consumer owned index */
660 return (f->head_chunk->data + (f->head - f->head_chunk->start_byte));
664 svm_fifo_tail (svm_fifo_t * f)
666 /* load-relaxed: producer owned index */
667 return (f->tail_chunk->data + (f->tail - f->tail_chunk->start_byte));
671 svm_fifo_n_subscribers (svm_fifo_t * f)
673 return f->n_subscribers;
677 * Check if fifo has out-of-order data
680 * @return 1 if fifo has ooo data, 0 otherwise
683 svm_fifo_has_ooo_data (svm_fifo_t * f)
685 return f->ooos_list_head != OOO_SEGMENT_INVALID_INDEX;
688 static inline ooo_segment_t *
689 svm_fifo_newest_ooo_segment (svm_fifo_t * f)
691 if (f->ooos_newest == OOO_SEGMENT_INVALID_INDEX)
693 return pool_elt_at_index (f->ooo_segments, f->ooos_newest);
697 svm_fifo_newest_ooo_segment_reset (svm_fifo_t * f)
699 f->ooos_newest = OOO_SEGMENT_INVALID_INDEX;
703 ooo_segment_offset_prod (svm_fifo_t * f, ooo_segment_t * s)
706 /* load-relaxed: producer owned index */
709 return f_distance_to (f, s->start, tail);
713 ooo_segment_length (svm_fifo_t * f, ooo_segment_t * s)
719 * Check if fifo has io event
722 * @return 1 if fifo has event, 0 otherwise
725 svm_fifo_has_event (svm_fifo_t * f)
731 * Set fifo event flag.
733 * Forces release semantics.
736 * @return 1 if flag was not set, 0 otherwise
739 svm_fifo_set_event (svm_fifo_t * f)
741 return !clib_atomic_swap_rel_n (&f->has_event, 1);
745 * Unset fifo event flag.
747 * Forces acquire semantics
752 svm_fifo_unset_event (svm_fifo_t * f)
754 clib_atomic_swap_acq_n (&f->has_event, 0);
758 * Set specific want notification flag
760 * For list of flags see @ref svm_fifo_deq_ntf_t
763 * @param ntf_type type of notification requested
766 svm_fifo_add_want_deq_ntf (svm_fifo_t * f, u8 ntf_type)
768 f->want_deq_ntf |= ntf_type;
772 * Clear specific want notification flag
774 * For list of flags see @ref svm_fifo_ntf_t
777 * @param ntf_type type of notification to be cleared
780 svm_fifo_del_want_deq_ntf (svm_fifo_t * f, u8 ntf_type)
782 f->want_deq_ntf &= ~ntf_type;
786 * Clear the want notification flag and set has notification
788 * Should be used after enqueuing an event. This clears the
789 * SVM_FIFO_WANT_NOTIF flag but it does not clear
790 * SVM_FIFO_WANT_NOTIF_IF_FULL. If the latter was set, has_ntf is
791 * set to avoid enqueueing events for for all dequeue operations until
792 * it is manually cleared.
797 svm_fifo_clear_deq_ntf (svm_fifo_t * f)
799 /* Set the flag if want_notif_if_full was the only ntf requested */
800 f->has_deq_ntf = f->want_deq_ntf == SVM_FIFO_WANT_DEQ_NOTIF_IF_FULL;
801 svm_fifo_del_want_deq_ntf (f, SVM_FIFO_WANT_DEQ_NOTIF);
805 * Clear has notification flag
807 * The fifo generates only one event per SVM_FIFO_WANT_NOTIF_IF_FULL
808 * request and sets has_ntf. To received new events the flag must be
809 * cleared using this function.
814 svm_fifo_reset_has_deq_ntf (svm_fifo_t * f)
820 * Check if fifo needs dequeue notification
822 * Determines based on notification request flags and state of the fifo if
823 * an event should be generated.
826 * @param n_last_deq number of bytes last dequeued
827 * @return 1 if event should be generated, 0 otherwise
830 svm_fifo_needs_deq_ntf (svm_fifo_t * f, u32 n_last_deq)
832 u8 want_ntf = f->want_deq_ntf;
834 if (PREDICT_TRUE (want_ntf == SVM_FIFO_NO_DEQ_NOTIF))
836 else if (want_ntf & SVM_FIFO_WANT_DEQ_NOTIF)
838 if (want_ntf & SVM_FIFO_WANT_DEQ_NOTIF_IF_FULL)
840 u32 max_deq = svm_fifo_max_dequeue_cons (f);
841 u32 nitems = f->nitems;
842 if (!f->has_deq_ntf && max_deq < nitems
843 && max_deq + n_last_deq >= nitems)
846 if (want_ntf & SVM_FIFO_WANT_DEQ_NOTIF_IF_EMPTY)
848 if (!f->has_deq_ntf && svm_fifo_is_empty (f))
854 #endif /* __included_ssvm_fifo_h__ */
857 * fd.io coding-style-patch-verification: ON
860 * eval: (c-set-style "gnu")