/* * Copyright (c) 2019 Cisco and/or its affiliates. * Licensed under the Apache License, Version 2.0 (the "License"); * you may not use this file except in compliance with the License. * You may obtain a copy of the License at: * * http://www.apache.org/licenses/LICENSE-2.0 * * Unless required by applicable law or agreed to in writing, software * distributed under the License is distributed on an "AS IS" BASIS, * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. * See the License for the specific language governing permissions and * limitations under the License. * * TCP byte tracker that can generate delivery rate estimates. Based on * draft-cheng-iccrg-delivery-rate-estimation-00 */ #include <vnet/tcp/tcp_bt.h> #include <vnet/tcp/tcp.h> #include <vnet/tcp/tcp_inlines.h> static tcp_bt_sample_t * bt_get_sample (tcp_byte_tracker_t * bt, u32 bts_index) { if (pool_is_free_index (bt->samples, bts_index)) return 0; return pool_elt_at_index (bt->samples, bts_index); } static tcp_bt_sample_t * bt_next_sample (tcp_byte_tracker_t * bt, tcp_bt_sample_t * bts) { return bt_get_sample (bt, bts->next); } static tcp_bt_sample_t * bt_prev_sample (tcp_byte_tracker_t * bt, tcp_bt_sample_t * bts) { return bt_get_sample (bt, bts->prev); } static u32 bt_sample_index (tcp_byte_tracker_t * bt, tcp_bt_sample_t * bts) { if (!bts) return TCP_BTS_INVALID_INDEX; return bts - bt->samples; } static inline int bt_seq_lt (u32 a, u32 b) { return seq_lt (a, b); } static tcp_bt_sample_t * bt_alloc_sample (tcp_byte_tracker_t * bt, u32 min_seq, u32 max_seq) { tcp_bt_sample_t *bts; pool_get_zero (bt->samples, bts); bts->next = bts->prev = TCP_BTS_INVALID_INDEX; bts->min_seq = min_seq; bts->max_seq = max_seq; rb_tree_add_custom (&bt->sample_lookup, bts->min_seq, bts - bt->samples, bt_seq_lt); return bts; } static void bt_free_sample (tcp_byte_tracker_t * bt, tcp_bt_sample_t * bts) { if (bts->prev != TCP_BTS_INVALID_INDEX) { tcp_bt_sample_t *prev = bt_prev_sample (bt, bts); prev->next = bts->next; } else bt->head = bts->next; if (bts->next != TCP_BTS_INVALID_INDEX) { tcp_bt_sample_t *next = bt_next_sample (bt, bts); next->prev = bts->prev; } else bt->tail = bts->prev; rb_tree_del_custom (&bt->sample_lookup, bts->min_seq, bt_seq_lt); if (CLIB_DEBUG) memset (bts, 0xfc, sizeof (*bts)); pool_put (bt->samples, bts); } static tcp_bt_sample_t * bt_split_sample (tcp_byte_tracker_t * bt, tcp_bt_sample_t * bts, u32 seq) { tcp_bt_sample_t *ns, *next; u32 bts_index; bts_index = bt_sample_index (bt, bts); ASSERT (seq_leq (bts->min_seq, seq) && seq_lt (seq, bts->max_seq)); ns = bt_alloc_sample (bt, seq, bts->max_seq); bts = bt_get_sample (bt, bts_index); *ns = *bts; ns->min_seq = seq; bts->max_seq = seq; next = bt_next_sample (bt, bts); if (next) next->prev = bt_sample_index (bt, ns); else bt->tail = bt_sample_index (bt, ns); bts->next = bt_sample_index (bt, ns); ns->prev = bt_sample_index (bt, bts); return ns; } static tcp_bt_sample_t * bt_merge_sample (tcp_byte_tracker_t * bt, tcp_bt_sample_t * prev, tcp_bt_sample_t * cur) { ASSERT (prev->max_seq == cur->min_seq); prev->max_seq = cur->max_seq; if (bt_sample_index (bt, cur) == bt->tail) bt->tail = bt_sample_index (bt, prev); bt_free_sample (bt, cur); return prev; } static tcp_bt_sample_t * bt_lookup_seq (tcp_byte_tracker_t * bt, u32 seq) { rb_tree_t *rt = &bt->sample_lookup; rb_node_t *cur, *prev; tcp_bt_sample_t *bts; cur = rb_node (rt, rt->root); if (rb_node_is_tnil (rt, cur)) return 0; while (seq != cur->key) { prev = cur; if (seq_lt (seq, cur->key)) cur = rb_node_left (rt, cur); else cur = rb_node_right (rt, cur); if (rb_node_is_tnil (rt, cur)) { /* Hit tnil as a left child. Find predecessor */ if (seq_lt (seq, prev->key)) { cur = rb_tree_predecessor (rt, prev); if (rb_node_is_tnil (rt, cur)) return 0; bts = bt_get_sample (bt, cur->opaque); } /* Hit tnil as a right child */ else { bts = bt_get_sample (bt, prev->opaque); } if (seq_geq (seq, bts->min_seq)) return bts; return 0; } } if (!rb_node_is_tnil (rt, cur)) return bt_get_sample (bt, cur->opaque); return 0; } static void bt_update_sample (tcp_byte_tracker_t * bt, tcp_bt_sample_t * bts, u32 seq) { rb_tree_del_custom (&bt->sample_lookup, bts->min_seq, bt_seq_lt); bts->min_seq = seq; rb_tree_add_custom (&bt->sample_lookup, bts->min_seq, bt_sample_index (bt, bts), bt_seq_lt); } static tcp_bt_sample_t * bt_fix_overlapped (tcp_byte_tracker_t * bt, tcp_bt_sample_t * start, u32 seq, u8 is_end) { tcp_bt_sample_t *cur, *next; cur = start; while (cur && seq_leq (cur->max_seq, seq)) { next = bt_next_sample (bt, cur); bt_free_sample (bt, cur); cur = next; } if (cur && seq_lt (cur->min_seq, seq)) bt_update_sample (bt, cur, seq); return cur; } int tcp_bt_is_sane (tcp_byte_tracker_t * bt) { tcp_bt_sample_t *bts, *tmp; if (pool_elts (bt->samples) != pool_elts (bt->sample_lookup.nodes) - 1) return 0; if (bt->head == TCP_BTS_INVALID_INDEX) { if (bt->tail != TCP_BTS_INVALID_INDEX) return 0; if (pool_elts (bt->samples) != 0) return 0; return 1; } bts = bt_get_sample (bt, bt->tail); if (!bts) return 0; bts = bt_get_sample (bt, bt->head); if (!bts || bts->prev != TCP_BTS_INVALID_INDEX) return 0; while (bts) { tmp = bt_lookup_seq (bt, bts->min_seq); if (!tmp) return 0; if (tmp != bts) return 0; tmp = bt_next_sample (bt, bts); if (tmp) { if (tmp->prev != bt_sample_index (bt, bts)) { clib_warning ("next %u thinks prev is %u should be %u", bts->next, tmp->prev, bt_sample_index (bt, bts)); return 0; } if (!seq_lt (bts->min_seq, tmp->min_seq)) return 0; } else { if (bt->tail != bt_sample_index (bt, bts)) return 0; if (bts->next != TCP_BTS_INVALID_INDEX) return 0; } bts = tmp; } return 1; } static tcp_bt_sample_t * tcp_bt_alloc_tx_sample (tcp_connection_t * tc, u32 min_seq, u32 max_seq) { tcp_bt_sample_t *bts; bts = bt_alloc_sample (tc->bt, min_seq, max_seq); bts->delivered = tc->delivered; bts->delivered_time = tc->delivered_time; bts->tx_time = tcp_time_now_us (tc->c_thread_index); bts->first_tx_time = tc->first_tx_time; bts->flags |= tc->app_limited ? TCP_BTS_IS_APP_LIMITED : 0; bts->tx_in_flight = tcp_flight_size (tc); bts->tx_lost = tc->lost; return bts; } void tcp_bt_check_app_limited (tcp_connection_t * tc) { u32 available_bytes, flight_size; available_bytes = transport_max_tx_dequeue (&tc->connection); flight_size = tcp_flight_size (tc); /* Not enough bytes to fill the cwnd */ if (available_bytes + flight_size + tc->snd_mss < tc->cwnd /* Bytes considered lost have been retransmitted */ && tc->sack_sb.lost_bytes <= tc->snd_rxt_bytes) tc->app_limited = tc->delivered + flight_size ? : 1; } void tcp_bt_track_tx (tcp_connection_t * tc, u32 len) { tcp_byte_tracker_t *bt = tc->bt; tcp_bt_sample_t *bts, *tail; u32 bts_index; tail = bt_get_sample (bt, bt->tail); if (tail && tail->max_seq == tc->snd_nxt && !(tail->flags & TCP_BTS_IS_SACKED) && tail->tx_time == tcp_time_now_us (tc->c_thread_index)) { tail->max_seq += len; return; } if (tc->snd_una == tc->snd_nxt) { tc->delivered_time = tcp_time_now_us (tc->c_thread_index); tc->first_tx_time = tc->delivered_time; } bts = tcp_bt_alloc_tx_sample (tc, tc->snd_nxt, tc->snd_nxt + len); bts_index = bt_sample_index (bt, bts); tail = bt_get_sample (bt, bt->tail); if (tail) { tail->next = bts_index; bts->prev = bt->tail; bt->tail = bts_index; } else { bt->tail = bt->head = bts_index; } } void tcp_bt_track_rxt (tcp_connection_t * tc, u32 start, u32 end) { tcp_byte_tracker_t *bt = tc->bt; tcp_bt_sample_t *bts, *next, *cur, *prev, *nbts; u32 bts_index, cur_index, next_index, prev_index, max_seq; u8 is_end = end == tc->snd_nxt; tcp_bts_flags_t bts_flags; /* Contiguous blocks retransmitted at the same time */ bts = bt_get_sample (bt, bt->last_ooo); if (bts && bts->max_seq == start && bts->tx_time == tcp_time_now_us (tc->c_thread_index)) { bts->max_seq = end; next = bt_next_sample (bt, bts); if (next) bt_fix_overlapped (bt, next, end, is_end); return; } /* Find original tx sample and cache flags in case the sample * is freed or the pool moves */ bts = bt_lookup_seq (bt, start); bts_flags = bts->flags; ASSERT (bts != 0 && seq_geq (start, bts->min_seq)); /* Head in the past */ if (seq_lt (bts->min_seq, tc->snd_una)) bt_update_sample (bt, bts, tc->snd_una); /* Head overlap */ if (bts->min_seq == start) { prev_index = bts->prev; next = bt_fix_overlapped (bt, bts, end, is_end); /* bts might no longer be valid from here */ next_index = bt_sample_index (bt, next); cur = tcp_bt_alloc_tx_sample (tc, start, end); cur->flags |= TCP_BTS_IS_RXT; if (bts_flags & TCP_BTS_IS_RXT) cur->flags |= TCP_BTS_IS_RXT_LOST; cur->next = next_index; cur->prev = prev_index; cur_index = bt_sample_index (bt, cur); if (next_index != TCP_BTS_INVALID_INDEX) { next = bt_get_sample (bt, next_index); next->prev = cur_index; } else { bt->tail = cur_index; } if (prev_index != TCP_BTS_INVALID_INDEX) { prev = bt_get_sample (bt, prev_index); prev->next = cur_index; } else { bt->head = cur_index; } bt->last_ooo = cur_index; return; } bts_index = bt_sample_index (bt, bts); next = bt_next_sample (bt, bts); if (next) bt_fix_overlapped (bt, next, end, is_end); max_seq = bts->max_seq; ASSERT (seq_lt (start, max_seq)); /* Have to split or tail overlap */ cur = tcp_bt_alloc_tx_sample (tc, start, end); cur->flags |= TCP_BTS_IS_RXT; if (bts_flags & TCP_BTS_IS_RXT) cur->flags |= TCP_BTS_IS_RXT_LOST; cur->prev = bts_index; cur_index = bt_sample_index (bt, cur); /* Split. Allocate another sample */ if (seq_lt (end, max_seq)) { nbts = tcp_bt_alloc_tx_sample (tc, end, bts->max_seq); cur = bt_get_sample (bt, cur_index); bts = bt_get_sample (bt, bts_index); *nbts = *bts; nbts->min_seq = end; if (nbts->next != TCP_BTS_INVALID_INDEX) { next = bt_get_sample (bt, nbts->next); next->prev = bt_sample_index (bt, nbts); } else bt->tail = bt_sample_index (bt, nbts); bts->next = nbts->prev = cur_index; cur->next = bt_sample_index (bt, nbts); bts->max_seq = start; bt->last_ooo = cur_index; } /* Tail completely overlapped */ else { bts = bt_get_sample (bt, bts_index); bts->max_seq = start; if (bts->next != TCP_BTS_INVALID_INDEX) { next = bt_get_sample (bt, bts->next); next->prev = cur_index; } else bt->tail = cur_index; cur->next = bts->next; bts->next = cur_index; bt->last_ooo = cur_index; } } static void tcp_bt_sample_to_rate_sample (tcp_connection_t * tc, tcp_bt_sample_t * bts, tcp_rate_sample_t * rs) { if (bts->flags & TCP_BTS_IS_SACKED) return; if (rs->prior_delivered && rs->prior_delivered >= bts->delivered) return; rs->prior_delivered = bts->delivered; rs->prior_time = bts->delivered_time; rs->interval_time = bts->tx_time - bts->first_tx_time; rs->rtt_time = tc->delivered_time - bts->tx_time; rs->flags = bts->flags; rs->tx_in_flight = bts->tx_in_flight; rs->tx_lost = bts->tx_lost; tc->first_tx_time = bts->tx_time; } static void tcp_bt_walk_samples (tcp_connection_t * tc, tcp_rate_sample_t * rs) { tcp_byte_tracker_t *bt = tc->bt; tcp_bt_sample_t *next, *cur; cur = bt_get_sample (bt, bt->head); while (cur && seq_leq (cur->max_seq, tc->snd_una)) { next = bt_next_sample (bt, cur); tcp_bt_sample_to_rate_sample (tc, cur, rs); bt_free_sample (bt, cur); cur = next; } if (cur && seq_lt (cur->min_seq, tc->snd_una)) { bt_update_sample (bt, cur, tc->snd_una); tcp_bt_sample_to_rate_sample (tc, cur, rs); } } static void tcp_bt_walk_samples_ooo (tcp_connection_t * tc, tcp_rate_sample_t * rs) { sack_block_t *blks = tc->rcv_opts.sacks, *blk; tcp_byte_tracker_t *bt = tc->bt; tcp_bt_sample_t *cur, *prev, *next; int i; for (i = 0; i < vec_len (blks); i++) { blk = &blks[i]; /* Ignore blocks that are already covered by snd_una */ if (seq_lt (blk->end, tc->snd_una)) continue; cur = bt_lookup_seq (bt, blk->start); if (!cur) continue; ASSERT (seq_geq (blk->start, cur->min_seq) && seq_lt (blk->start, cur->max_seq)); /* Current should be split. Second part will be consumed */ if (PREDICT_FALSE (cur->min_seq != blk->start)) { cur = bt_split_sample (bt, cur, blk->start); prev = bt_prev_sample (bt, cur); } else prev = bt_prev_sample (bt, cur); while (cur && seq_leq (cur->max_seq, blk->end)) { if (!(cur->flags & TCP_BTS_IS_SACKED)) { tcp_bt_sample_to_rate_sample (tc, cur, rs); cur->flags |= TCP_BTS_IS_SACKED; if (prev && (prev->flags & TCP_BTS_IS_SACKED)) { cur = bt_merge_sample (bt, prev, cur); next = bt_next_sample (bt, cur); } else { next = bt_next_sample (bt, cur); if (next && (next->flags & TCP_BTS_IS_SACKED)) { cur = bt_merge_sample (bt, cur, next); next = bt_next_sample (bt, cur); } } } else next = bt_next_sample (bt, cur); prev = cur; cur = next; } if (cur && seq_lt (cur->min_seq, blk->end)) { tcp_bt_sample_to_rate_sample (tc, cur, rs); prev = bt_prev_sample (bt, cur); /* Extend previous to include the newly sacked bytes */ if (prev && (prev->flags & TCP_BTS_IS_SACKED)) { prev->max_seq = blk->end; bt_update_sample (bt, cur, blk->end); } /* Split sample into two. First part is consumed */ else { next = bt_split_sample (bt, cur, blk->end); cur = bt_prev_sample (bt, next); cur->flags |= TCP_BTS_IS_SACKED; } } } } void tcp_bt_sample_delivery_rate (tcp_connection_t * tc, tcp_rate_sample_t * rs) { u32 delivered; if (PREDICT_FALSE (tc->flags & TCP_CONN_FINSNT)) return; tc->lost += tc->sack_sb.last_lost_bytes; delivered = tc->bytes_acked + tc->sack_sb.last_sacked_bytes; /* Do not count bytes that were previously sacked again */ delivered -= tc->sack_sb.last_bytes_delivered; if (!delivered || tc->bt->head == TCP_BTS_INVALID_INDEX) return; tc->delivered += delivered; tc->delivered_time = tcp_time_now_us (tc->c_thread_index); if (tc->app_limited && tc->delivered > tc->app_limited) tc->app_limited = 0; if (tc->bytes_acked) tcp_bt_walk_samples (tc, rs); if (tc->sack_sb.last_sacked_bytes) tcp_bt_walk_samples_ooo (tc, rs); rs->interval_time = clib_max ((tc->delivered_time - rs->prior_time), rs->interval_time); rs->delivered = tc->delivered - rs->prior_delivered; rs->acked_and_sacked = delivered; rs->last_lost = tc->sack_sb.last_lost_bytes; rs->lost = tc->lost - rs->tx_lost; } void tcp_bt_flush_samples (tcp_connection_t * tc) { tcp_byte_tracker_t *bt = tc->bt; tcp_bt_sample_t *bts; u32 *samples = 0, *si; vec_validate (samples, pool_elts (bt->samples) - 1); vec_reset_length (samples); /* *INDENT-OFF* */ pool_foreach (bts, bt->samples) { vec_add1 (samples, bts - bt->samples); } /* *INDENT-ON* */ vec_foreach (si, samples) { bts = bt_get_sample (bt, *si); bt_free_sample (bt, bts); } vec_free (samples); } void tcp_bt_cleanup (tcp_connection_t * tc) { tcp_byte_tracker_t *bt = tc->bt; rb_tree_free_nodes (&bt->sample_lookup); pool_free (bt->samples); clib_mem_free (bt); tc->bt = 0; } void tcp_bt_init (tcp_connection_t * tc) { tcp_byte_tracker_t *bt; bt = clib_mem_alloc (sizeof (tcp_byte_tracker_t)); clib_memset (bt, 0, sizeof (tcp_byte_tracker_t)); rb_tree_init (&bt->sample_lookup); bt->head = bt->tail = TCP_BTS_INVALID_INDEX; tc->bt = bt; } u8 * format_tcp_bt_sample (u8 * s, va_list * args) { tcp_connection_t *tc = va_arg (*args, tcp_connection_t *); tcp_bt_sample_t *bts = va_arg (*args, tcp_bt_sample_t *); f64 now = tcp_time_now_us (tc->c_thread_index); s = format (s, "[%u, %u] d %u dt %.3f txt %.3f ftxt %.3f flags 0x%x", bts->min_seq - tc->iss, bts->max_seq - tc->iss, bts->delivered, now - bts->delivered_time, now - bts->tx_time, now - bts->first_tx_time, bts->flags); return s; } u8 * format_tcp_bt (u8 * s, va_list * args) { tcp_connection_t *tc = va_arg (*args, tcp_connection_t *); tcp_byte_tracker_t *bt = tc->bt; tcp_bt_sample_t *bts; bts = bt_get_sample (bt, bt->head); while (bts) { s = format (s, "%U\n", format_tcp_bt_sample, tc, bts); bts = bt_next_sample (bt, bts); } return s; } /* * fd.io coding-style-patch-verification: ON * * Local Variables: * eval: (c-set-style "gnu") * End: */