2 * Copyright (c) 2019 Cisco and/or its affiliates.
3 * Licensed under the Apache License, Version 2.0 (the "License");
4 * you may not use this file except in compliance with the License.
5 * You may obtain a copy of the License at:
7 * http://www.apache.org/licenses/LICENSE-2.0
9 * Unless required by applicable law or agreed to in writing, software
10 * distributed under the License is distributed on an "AS IS" BASIS,
11 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
12 * See the License for the specific language governing permissions and
13 * limitations under the License.
15 * TCP byte tracker that can generate delivery rate estimates. Based on
16 * draft-cheng-iccrg-delivery-rate-estimation-00
19 #include <vnet/tcp/tcp.h>
21 static tcp_bt_sample_t *
22 bt_get_sample (tcp_byte_tracker_t * bt, u32 bts_index)
24 if (pool_is_free_index (bt->samples, bts_index))
26 return pool_elt_at_index (bt->samples, bts_index);
29 static tcp_bt_sample_t *
30 bt_next_sample (tcp_byte_tracker_t * bt, tcp_bt_sample_t * bts)
32 return bt_get_sample (bt, bts->next);
35 static tcp_bt_sample_t *
36 bt_prev_sample (tcp_byte_tracker_t * bt, tcp_bt_sample_t * bts)
38 return bt_get_sample (bt, bts->prev);
42 bt_sample_index (tcp_byte_tracker_t * bt, tcp_bt_sample_t * bts)
45 return TCP_BTS_INVALID_INDEX;
46 return bts - bt->samples;
50 bt_seq_lt (u32 a, u32 b)
55 static tcp_bt_sample_t *
56 bt_alloc_sample (tcp_byte_tracker_t * bt, u32 min_seq, u32 max_seq)
60 pool_get_zero (bt->samples, bts);
61 bts->next = bts->prev = TCP_BTS_INVALID_INDEX;
62 bts->min_seq = min_seq;
63 bts->max_seq = max_seq;
64 rb_tree_add_custom (&bt->sample_lookup, bts->min_seq, bts - bt->samples,
70 bt_free_sample (tcp_byte_tracker_t * bt, tcp_bt_sample_t * bts)
72 if (bts->prev != TCP_BTS_INVALID_INDEX)
74 tcp_bt_sample_t *prev = bt_prev_sample (bt, bts);
75 prev->next = bts->next;
80 if (bts->next != TCP_BTS_INVALID_INDEX)
82 tcp_bt_sample_t *next = bt_next_sample (bt, bts);
83 next->prev = bts->prev;
88 rb_tree_del_custom (&bt->sample_lookup, bts->min_seq, bt_seq_lt);
90 memset (bts, 0xfc, sizeof (*bts));
91 pool_put (bt->samples, bts);
94 static tcp_bt_sample_t *
95 bt_split_sample (tcp_byte_tracker_t * bt, tcp_bt_sample_t * bts, u32 seq)
97 tcp_bt_sample_t *ns, *next;
100 bts_index = bt_sample_index (bt, bts);
102 ASSERT (seq_leq (bts->min_seq, seq) && seq_lt (seq, bts->max_seq));
104 ns = bt_alloc_sample (bt, seq, bts->max_seq);
105 bts = bt_get_sample (bt, bts_index);
111 next = bt_next_sample (bt, bts);
113 next->prev = bt_sample_index (bt, ns);
115 bt->tail = bt_sample_index (bt, ns);
117 bts->next = bt_sample_index (bt, ns);
118 ns->prev = bt_sample_index (bt, bts);
123 static tcp_bt_sample_t *
124 bt_merge_sample (tcp_byte_tracker_t * bt, tcp_bt_sample_t * prev,
125 tcp_bt_sample_t * cur)
127 ASSERT (prev->max_seq == cur->min_seq);
128 prev->max_seq = cur->max_seq;
129 if (bt_sample_index (bt, cur) == bt->tail)
130 bt->tail = bt_sample_index (bt, prev);
131 bt_free_sample (bt, cur);
135 static tcp_bt_sample_t *
136 bt_lookup_seq (tcp_byte_tracker_t * bt, u32 seq)
138 rb_tree_t *rt = &bt->sample_lookup;
139 rb_node_t *cur, *prev;
140 tcp_bt_sample_t *bts;
142 cur = rb_node (rt, rt->root);
143 if (rb_node_is_tnil (rt, cur))
146 while (seq != cur->key)
149 if (seq_lt (seq, cur->key))
150 cur = rb_node_left (rt, cur);
152 cur = rb_node_right (rt, cur);
154 if (rb_node_is_tnil (rt, cur))
156 /* Hit tnil as a left child. Find predecessor */
157 if (seq_lt (seq, prev->key))
159 cur = rb_tree_predecessor (rt, prev);
160 if (rb_node_is_tnil (rt, cur))
162 bts = bt_get_sample (bt, cur->opaque);
164 /* Hit tnil as a right child */
167 bts = bt_get_sample (bt, prev->opaque);
170 if (seq_geq (seq, bts->min_seq))
177 if (!rb_node_is_tnil (rt, cur))
178 return bt_get_sample (bt, cur->opaque);
184 bt_update_sample (tcp_byte_tracker_t * bt, tcp_bt_sample_t * bts, u32 seq)
186 rb_tree_del_custom (&bt->sample_lookup, bts->min_seq, bt_seq_lt);
188 rb_tree_add_custom (&bt->sample_lookup, bts->min_seq,
189 bt_sample_index (bt, bts), bt_seq_lt);
192 static tcp_bt_sample_t *
193 bt_fix_overlapped (tcp_byte_tracker_t * bt, tcp_bt_sample_t * start,
196 tcp_bt_sample_t *cur, *next;
199 while (cur && seq_leq (cur->max_seq, seq))
201 next = bt_next_sample (bt, cur);
202 bt_free_sample (bt, cur);
206 if (cur && seq_lt (cur->min_seq, seq))
207 bt_update_sample (bt, cur, seq);
213 tcp_bt_is_sane (tcp_byte_tracker_t * bt)
215 tcp_bt_sample_t *bts, *tmp;
217 if (pool_elts (bt->samples) != pool_elts (bt->sample_lookup.nodes) - 1)
220 if (bt->head == TCP_BTS_INVALID_INDEX)
222 if (bt->tail != TCP_BTS_INVALID_INDEX)
224 if (pool_elts (bt->samples) != 0)
229 bts = bt_get_sample (bt, bt->tail);
233 bts = bt_get_sample (bt, bt->head);
234 if (!bts || bts->prev != TCP_BTS_INVALID_INDEX)
239 tmp = bt_lookup_seq (bt, bts->min_seq);
244 tmp = bt_next_sample (bt, bts);
247 if (tmp->prev != bt_sample_index (bt, bts))
249 clib_warning ("next %u thinks prev is %u should be %u",
250 bts->next, tmp->prev, bt_sample_index (bt, bts));
253 if (!seq_lt (bts->min_seq, tmp->min_seq))
258 if (bt->tail != bt_sample_index (bt, bts))
260 if (bts->next != TCP_BTS_INVALID_INDEX)
268 static tcp_bt_sample_t *
269 tcp_bt_alloc_tx_sample (tcp_connection_t * tc, u32 min_seq, u32 max_seq)
271 tcp_bt_sample_t *bts;
272 bts = bt_alloc_sample (tc->bt, min_seq, max_seq);
273 bts->delivered = tc->delivered;
274 bts->delivered_time = tc->delivered_time;
275 bts->tx_time = tcp_time_now_us (tc->c_thread_index);
276 bts->first_tx_time = tc->first_tx_time;
277 bts->flags |= tc->app_limited ? TCP_BTS_IS_APP_LIMITED : 0;
278 bts->tx_in_flight = tcp_flight_size (tc);
279 bts->tx_lost = tc->lost;
284 tcp_bt_check_app_limited (tcp_connection_t * tc)
286 u32 available_bytes, flight_size;
288 available_bytes = transport_max_tx_dequeue (&tc->connection);
289 flight_size = tcp_flight_size (tc);
291 /* Not enough bytes to fill the cwnd */
292 if (available_bytes + flight_size + tc->snd_mss < tc->cwnd
293 /* Bytes considered lost have been retransmitted */
294 && tc->sack_sb.lost_bytes <= tc->snd_rxt_bytes)
295 tc->app_limited = tc->delivered + flight_size ? : 1;
299 tcp_bt_track_tx (tcp_connection_t * tc, u32 len)
301 tcp_byte_tracker_t *bt = tc->bt;
302 tcp_bt_sample_t *bts, *tail;
305 tail = bt_get_sample (bt, bt->tail);
306 if (tail && tail->max_seq == tc->snd_nxt
307 && tail->tx_time == tcp_time_now_us (tc->c_thread_index))
309 tail->max_seq += len;
313 if (tc->snd_una == tc->snd_nxt)
315 tc->delivered_time = tcp_time_now_us (tc->c_thread_index);
316 tc->first_tx_time = tc->delivered_time;
319 bts = tcp_bt_alloc_tx_sample (tc, tc->snd_nxt, tc->snd_nxt + len);
320 bts_index = bt_sample_index (bt, bts);
321 tail = bt_get_sample (bt, bt->tail);
324 tail->next = bts_index;
325 bts->prev = bt->tail;
326 bt->tail = bts_index;
330 bt->tail = bt->head = bts_index;
335 tcp_bt_track_rxt (tcp_connection_t * tc, u32 start, u32 end)
337 tcp_byte_tracker_t *bt = tc->bt;
338 tcp_bt_sample_t *bts, *next, *cur, *prev, *nbts;
339 u32 bts_index, cur_index, next_index, prev_index, max_seq;
340 u8 is_end = end == tc->snd_nxt;
342 /* Contiguous blocks retransmitted at the same time */
343 bts = bt_get_sample (bt, bt->last_ooo);
344 if (bts && bts->max_seq == start
345 && bts->tx_time == tcp_time_now_us (tc->c_thread_index))
348 next = bt_next_sample (bt, bts);
350 bt_fix_overlapped (bt, next, end, is_end);
355 /* Find original tx sample */
356 bts = bt_lookup_seq (bt, start);
358 ASSERT (bts != 0 && seq_geq (start, bts->min_seq));
360 /* Head in the past */
361 if (seq_lt (bts->min_seq, tc->snd_una))
362 bt_update_sample (bt, bts, tc->snd_una);
365 if (bts->min_seq == start)
367 prev_index = bts->prev;
368 next = bt_fix_overlapped (bt, bts, end, is_end);
369 next_index = bt_sample_index (bt, next);
371 cur = tcp_bt_alloc_tx_sample (tc, start, end);
372 cur->flags |= TCP_BTS_IS_RXT;
373 if (bts->flags & TCP_BTS_IS_RXT)
374 cur->flags |= TCP_BTS_IS_RXT_LOST;
375 cur->next = next_index;
376 cur->prev = prev_index;
378 cur_index = bt_sample_index (bt, cur);
380 if (next_index != TCP_BTS_INVALID_INDEX)
382 next = bt_get_sample (bt, next_index);
383 next->prev = cur_index;
387 bt->tail = cur_index;
390 if (prev_index != TCP_BTS_INVALID_INDEX)
392 prev = bt_get_sample (bt, prev_index);
393 prev->next = cur_index;
397 bt->head = cur_index;
400 bt->last_ooo = cur_index;
404 bts_index = bt_sample_index (bt, bts);
405 next = bt_next_sample (bt, bts);
407 bt_fix_overlapped (bt, next, end, is_end);
409 max_seq = bts->max_seq;
410 ASSERT (seq_lt (start, max_seq));
412 /* Have to split or tail overlap */
413 cur = tcp_bt_alloc_tx_sample (tc, start, end);
414 cur->flags |= TCP_BTS_IS_RXT;
415 if (bts->flags & TCP_BTS_IS_RXT)
416 cur->flags |= TCP_BTS_IS_RXT_LOST;
417 cur->prev = bts_index;
418 cur_index = bt_sample_index (bt, cur);
420 /* Split. Allocate another sample */
421 if (seq_lt (end, max_seq))
423 nbts = tcp_bt_alloc_tx_sample (tc, end, bts->max_seq);
424 cur = bt_get_sample (bt, cur_index);
425 bts = bt_get_sample (bt, bts_index);
430 if (nbts->next != TCP_BTS_INVALID_INDEX)
432 next = bt_get_sample (bt, nbts->next);
433 next->prev = bt_sample_index (bt, nbts);
436 bt->tail = bt_sample_index (bt, nbts);
438 bts->next = nbts->prev = cur_index;
439 cur->next = bt_sample_index (bt, nbts);
441 bts->max_seq = start;
442 bt->last_ooo = cur_index;
444 /* Tail completely overlapped */
447 bts = bt_get_sample (bt, bts_index);
448 bts->max_seq = start;
450 if (bts->next != TCP_BTS_INVALID_INDEX)
452 next = bt_get_sample (bt, bts->next);
453 next->prev = cur_index;
456 bt->tail = cur_index;
458 cur->next = bts->next;
459 bts->next = cur_index;
461 bt->last_ooo = cur_index;
466 tcp_bt_sample_to_rate_sample (tcp_connection_t * tc, tcp_bt_sample_t * bts,
467 tcp_rate_sample_t * rs)
469 if (bts->flags & TCP_BTS_IS_SACKED)
472 if (rs->prior_delivered && rs->prior_delivered >= bts->delivered)
475 rs->prior_delivered = bts->delivered;
476 rs->prior_time = bts->delivered_time;
477 rs->interval_time = bts->tx_time - bts->first_tx_time;
478 rs->rtt_time = tc->delivered_time - bts->tx_time;
479 rs->flags = bts->flags;
480 rs->tx_in_flight = bts->tx_in_flight;
481 rs->tx_lost = bts->tx_lost;
482 tc->first_tx_time = bts->tx_time;
486 tcp_bt_walk_samples (tcp_connection_t * tc, tcp_rate_sample_t * rs)
488 tcp_byte_tracker_t *bt = tc->bt;
489 tcp_bt_sample_t *next, *cur;
491 cur = bt_get_sample (bt, bt->head);
492 while (cur && seq_leq (cur->max_seq, tc->snd_una))
494 next = bt_next_sample (bt, cur);
495 tcp_bt_sample_to_rate_sample (tc, cur, rs);
496 bt_free_sample (bt, cur);
500 if (cur && seq_lt (cur->min_seq, tc->snd_una))
501 tcp_bt_sample_to_rate_sample (tc, cur, rs);
505 tcp_bt_walk_samples_ooo (tcp_connection_t * tc, tcp_rate_sample_t * rs)
507 sack_block_t *blks = tc->rcv_opts.sacks, *blk;
508 tcp_byte_tracker_t *bt = tc->bt;
509 tcp_bt_sample_t *cur, *prev, *next;
512 for (i = 0; i < vec_len (blks); i++)
516 /* Ignore blocks that are already covered by snd_una */
517 if (seq_lt (blk->end, tc->snd_una))
520 cur = bt_lookup_seq (bt, blk->start);
524 ASSERT (seq_geq (blk->start, cur->min_seq)
525 && seq_lt (blk->start, cur->max_seq));
527 /* Current should be split. Second part will be consumed */
528 if (PREDICT_FALSE (cur->min_seq != blk->start))
530 cur = bt_split_sample (bt, cur, blk->start);
531 prev = bt_prev_sample (bt, cur);
534 prev = bt_prev_sample (bt, cur);
536 while (cur && seq_leq (cur->max_seq, blk->end))
538 if (!(cur->flags & TCP_BTS_IS_SACKED))
540 tcp_bt_sample_to_rate_sample (tc, cur, rs);
541 cur->flags |= TCP_BTS_IS_SACKED;
542 if (prev && (prev->flags & TCP_BTS_IS_SACKED))
544 cur = bt_merge_sample (bt, prev, cur);
545 next = bt_next_sample (bt, cur);
549 next = bt_next_sample (bt, cur);
550 if (next && (next->flags & TCP_BTS_IS_SACKED))
552 cur = bt_merge_sample (bt, cur, next);
553 next = bt_next_sample (bt, cur);
558 next = bt_next_sample (bt, cur);
564 if (cur && seq_lt (cur->min_seq, blk->end))
566 tcp_bt_sample_to_rate_sample (tc, cur, rs);
567 prev = bt_prev_sample (bt, cur);
568 /* Extend previous to include the newly sacked bytes */
569 if (prev && (prev->flags & TCP_BTS_IS_SACKED))
571 prev->max_seq = blk->end;
572 bt_update_sample (bt, cur, blk->end);
574 /* Split sample into two. First part is consumed */
577 next = bt_split_sample (bt, cur, blk->end);
578 cur = bt_prev_sample (bt, next);
579 cur->flags |= TCP_BTS_IS_SACKED;
586 tcp_bt_sample_delivery_rate (tcp_connection_t * tc, tcp_rate_sample_t * rs)
590 if (PREDICT_FALSE (tc->flags & TCP_CONN_FINSNT))
593 tc->lost += tc->sack_sb.last_lost_bytes;
595 delivered = tc->bytes_acked + tc->sack_sb.last_sacked_bytes;
596 if (!delivered || tc->bt->head == TCP_BTS_INVALID_INDEX)
599 /* Do not count bytes that were previously sacked again */
600 tc->delivered += delivered - tc->sack_sb.last_bytes_delivered;
601 tc->delivered_time = tcp_time_now_us (tc->c_thread_index);
603 if (tc->app_limited && tc->delivered > tc->app_limited)
607 tcp_bt_walk_samples (tc, rs);
609 if (tc->sack_sb.last_sacked_bytes)
610 tcp_bt_walk_samples_ooo (tc, rs);
612 rs->interval_time = clib_max ((tc->delivered_time - rs->prior_time),
614 rs->delivered = tc->delivered - rs->prior_delivered;
615 rs->acked_and_sacked = delivered;
616 rs->last_lost = tc->sack_sb.last_lost_bytes;
617 rs->lost = tc->lost - rs->tx_lost;
621 tcp_bt_flush_samples (tcp_connection_t * tc)
623 tcp_byte_tracker_t *bt = tc->bt;
624 tcp_bt_sample_t *bts;
625 u32 *samples = 0, *si;
627 vec_validate (samples, pool_elts (bt->samples) - 1);
628 vec_reset_length (samples);
631 pool_foreach (bts, bt->samples, ({
632 vec_add1 (samples, bts - bt->samples);
636 vec_foreach (si, samples)
638 bts = bt_get_sample (bt, *si);
639 bt_free_sample (bt, bts);
646 tcp_bt_cleanup (tcp_connection_t * tc)
648 tcp_byte_tracker_t *bt = tc->bt;
650 rb_tree_free_nodes (&bt->sample_lookup);
651 pool_free (bt->samples);
657 tcp_bt_init (tcp_connection_t * tc)
659 tcp_byte_tracker_t *bt;
661 bt = clib_mem_alloc (sizeof (tcp_byte_tracker_t));
662 clib_memset (bt, 0, sizeof (tcp_byte_tracker_t));
664 rb_tree_init (&bt->sample_lookup);
665 bt->head = bt->tail = TCP_BTS_INVALID_INDEX;
670 format_tcp_bt_sample (u8 * s, va_list * args)
672 tcp_connection_t *tc = va_arg (*args, tcp_connection_t *);
673 tcp_bt_sample_t *bts = va_arg (*args, tcp_bt_sample_t *);
674 f64 now = tcp_time_now_us (tc->c_thread_index);
675 s = format (s, "[%u, %u] d %u dt %.3f txt %.3f ftxt %.3f flags 0x%x",
676 bts->min_seq - tc->iss, bts->max_seq - tc->iss, bts->delivered,
677 now - bts->delivered_time, now - bts->tx_time,
678 now - bts->first_tx_time, bts->flags);
683 format_tcp_bt (u8 * s, va_list * args)
685 tcp_connection_t *tc = va_arg (*args, tcp_connection_t *);
686 tcp_byte_tracker_t *bt = tc->bt;
687 tcp_bt_sample_t *bts;
689 bts = bt_get_sample (bt, bt->head);
692 s = format (s, "%U\n", format_tcp_bt_sample, tc, bts);
693 bts = bt_next_sample (bt, bts);
700 * fd.io coding-style-patch-verification: ON
703 * eval: (c-set-style "gnu")