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authorFlorin Coras <fcoras@cisco.com>2019-09-12 18:36:44 -0700
committerJohn Lo <loj@cisco.com>2019-09-25 14:54:42 +0000
commit36ebcfffbc7ab0e83b4bb8dfaec16bf16cafb954 (patch)
treefe9803af08fd55cf1c9419d6e58f45394e155a7b /src/vnet/tcp/tcp.c
parent54c93cfc2556d9c6d2cf472f51d4c2866a556ef6 (diff)
tcp: use sacks for timer based recovery
Type: feature If available, reuse sack scoreboard in timer triggered retransmit to minimize spurious retransmits. Additional changes/refactoring: - limited transmit updates - add sacked rxt count to scoreboard - prr pacing of fast retransmits - startup pacing updates - changed loss window to flight + mss Change-Id: I057de6a9d6401698bd1031d5cf5cfbb62f2bdf61 Signed-off-by: Florin Coras <fcoras@cisco.com>
Diffstat (limited to 'src/vnet/tcp/tcp.c')
-rw-r--r--src/vnet/tcp/tcp.c45
1 files changed, 24 insertions, 21 deletions
diff --git a/src/vnet/tcp/tcp.c b/src/vnet/tcp/tcp.c
index 12e241984cf..75a45a448bd 100644
--- a/src/vnet/tcp/tcp.c
+++ b/src/vnet/tcp/tcp.c
@@ -701,17 +701,15 @@ tcp_init_snd_vars (tcp_connection_t * tc)
tc->snd_una = tc->iss;
tc->snd_nxt = tc->iss + 1;
tc->snd_una_max = tc->snd_nxt;
- tc->srtt = 0;
+ tc->srtt = 100; /* 100 ms */
}
void
tcp_enable_pacing (tcp_connection_t * tc)
{
- u32 initial_bucket, byte_rate;
- initial_bucket = 16 * tc->snd_mss;
- byte_rate = 2 << 16;
- transport_connection_tx_pacer_init (&tc->connection, byte_rate,
- initial_bucket);
+ u32 byte_rate;
+ byte_rate = tc->cwnd / (tc->srtt * TCP_TICK);
+ transport_connection_tx_pacer_init (&tc->connection, byte_rate, tc->cwnd);
tc->mrtt_us = (u32) ~ 0;
}
@@ -725,10 +723,11 @@ tcp_connection_init_vars (tcp_connection_t * tc)
tcp_connection_timers_init (tc);
tcp_init_mss (tc);
scoreboard_init (&tc->sack_sb);
- tcp_cc_init (tc);
if (tc->state == TCP_STATE_SYN_RCVD)
tcp_init_snd_vars (tc);
+ tcp_cc_init (tc);
+
if (!tc->c_is_ip4 && ip6_address_is_link_local_unicast (&tc->c_rmt_ip6))
tcp_add_del_adjacency (tc, 1);
@@ -921,7 +920,7 @@ format_tcp_congestion (u8 * s, va_list * args)
s = format (s, "%U ", format_tcp_congestion_status, tc);
s = format (s, "algo %s cwnd %u ssthresh %u bytes_acked %u\n",
tc->cc_algo->name, tc->cwnd, tc->ssthresh, tc->bytes_acked);
- s = format (s, "%Ucc space %u prev_cwnd %u prev_ssthresh %u rtx_bytes %u\n",
+ s = format (s, "%Ucc space %u prev_cwnd %u prev_ssthresh %u rxt_bytes %u\n",
format_white_space, indent, tcp_available_cc_snd_space (tc),
tc->prev_cwnd, tc->prev_ssthresh, tc->snd_rxt_bytes);
s = format (s, "%Usnd_congestion %u dupack %u limited_transmit %u\n",
@@ -1141,8 +1140,9 @@ format_tcp_scoreboard (u8 * s, va_list * args)
sack_scoreboard_hole_t *hole;
u32 indent = format_get_indent (s);
- s = format (s, "sacked_bytes %u last_sacked_bytes %u lost_bytes %u\n",
- sb->sacked_bytes, sb->last_sacked_bytes, sb->lost_bytes);
+ s = format (s, "sacked %u last_sacked %u lost %u last_lost %u\n",
+ sb->sacked_bytes, sb->last_sacked_bytes, sb->lost_bytes,
+ sb->last_lost_bytes);
s = format (s, "%Ulast_bytes_delivered %u high_sacked %u is_reneging %u\n",
format_white_space, indent, sb->last_bytes_delivered,
sb->high_sacked - tc->iss, sb->is_reneging);
@@ -1247,7 +1247,7 @@ tcp_round_snd_space (tcp_connection_t * tc, u32 snd_space)
static inline u32
tcp_snd_space_inline (tcp_connection_t * tc)
{
- int snd_space, snt_limited;
+ int snd_space;
if (PREDICT_FALSE (tcp_in_fastrecovery (tc)
|| tc->state == TCP_STATE_CLOSED))
@@ -1255,18 +1255,21 @@ tcp_snd_space_inline (tcp_connection_t * tc)
snd_space = tcp_available_output_snd_space (tc);
- /* If we haven't gotten dupacks or if we did and have gotten sacked
- * bytes then we can still send as per Limited Transmit (RFC3042) */
- if (PREDICT_FALSE (tc->rcv_dupacks != 0
- && (tcp_opts_sack_permitted (tc)
- && tc->sack_sb.last_sacked_bytes == 0)))
+ /* If we got dupacks or sacked bytes but we're not yet in recovery, try
+ * to force the peer to send enough dupacks to start retransmitting as
+ * per Limited Transmit (RFC3042)
+ */
+ if (PREDICT_FALSE (tc->rcv_dupacks != 0 || tc->sack_sb.sacked_bytes))
{
- if (tc->rcv_dupacks == 1 && tc->limited_transmit != tc->snd_nxt)
+ if (tc->limited_transmit != tc->snd_nxt
+ && (seq_lt (tc->limited_transmit, tc->snd_nxt - 2 * tc->snd_mss)
+ || seq_gt (tc->limited_transmit, tc->snd_nxt)))
tc->limited_transmit = tc->snd_nxt;
+
ASSERT (seq_leq (tc->limited_transmit, tc->snd_nxt));
- snt_limited = tc->snd_nxt - tc->limited_transmit;
- snd_space = clib_max (2 * tc->snd_mss - snt_limited, 0);
+ int snt_limited = tc->snd_nxt - tc->limited_transmit;
+ snd_space = clib_max ((int) 2 * tc->snd_mss - snt_limited, 0);
}
return tcp_round_snd_space (tc, snd_space);
}
@@ -1360,9 +1363,9 @@ tcp_connection_tx_pacer_reset (tcp_connection_t * tc, u32 window,
u32 start_bucket)
{
tcp_worker_ctx_t *wrk = tcp_get_worker (tc->c_thread_index);
- u32 byte_rate = window / ((f64) TCP_TICK * tc->srtt);
+ f64 srtt = clib_min ((f64) tc->srtt * TCP_TICK, tc->mrtt_us);
u64 last_time = wrk->vm->clib_time.last_cpu_time;
- transport_connection_tx_pacer_reset (&tc->connection, byte_rate,
+ transport_connection_tx_pacer_reset (&tc->connection, window / srtt,
start_bucket, last_time);
}