#define FLAG_SYN_ACKED 0x10 /* This ACK acknowledged SYN. */
#define FLAG_DATA_SACKED 0x20 /* New SACK. */
#define FLAG_ECE 0x40 /* ECE in this ACK */
+#define FLAG_LOST_RETRANS 0x80 /* This ACK marks some retransmission lost */
#define FLAG_SLOWPATH 0x100 /* Do not skip RFC checks for window update.*/
#define FLAG_ORIG_SACK_ACKED 0x200 /* Never retransmitted data are (s)acked */
#define FLAG_SND_UNA_ADVANCED 0x400 /* Snd_una was changed (!= FLAG_DATA_ACKED) */
* and the session is not interactive.
*/
-static inline bool tcp_in_quickack_mode(const struct sock *sk)
+static bool tcp_in_quickack_mode(struct sock *sk)
{
const struct inet_connection_sock *icsk = inet_csk(sk);
+ const struct dst_entry *dst = __sk_dst_get(sk);
- return icsk->icsk_ack.quick && !icsk->icsk_ack.pingpong;
+ return (dst && dst_metric(dst, RTAX_QUICKACK)) ||
+ (icsk->icsk_ack.quick && !icsk->icsk_ack.pingpong);
}
static void tcp_ecn_queue_cwr(struct tcp_sock *tp)
* TCP pacing, to smooth the burst on large writes when packets
* in flight is significantly lower than cwnd (or rwin)
*/
+int sysctl_tcp_pacing_ss_ratio __read_mostly = 200;
+int sysctl_tcp_pacing_ca_ratio __read_mostly = 120;
+
static void tcp_update_pacing_rate(struct sock *sk)
{
const struct tcp_sock *tp = tcp_sk(sk);
u64 rate;
/* set sk_pacing_rate to 200 % of current rate (mss * cwnd / srtt) */
- rate = (u64)tp->mss_cache * 2 * (USEC_PER_SEC << 3);
+ rate = (u64)tp->mss_cache * ((USEC_PER_SEC / 100) << 3);
+
+ /* current rate is (cwnd * mss) / srtt
+ * In Slow Start [1], set sk_pacing_rate to 200 % the current rate.
+ * In Congestion Avoidance phase, set it to 120 % the current rate.
+ *
+ * [1] : Normal Slow Start condition is (tp->snd_cwnd < tp->snd_ssthresh)
+ * If snd_cwnd >= (tp->snd_ssthresh / 2), we are approaching
+ * end of slow start and should slow down.
+ */
+ if (tp->snd_cwnd < tp->snd_ssthresh / 2)
+ rate *= sysctl_tcp_pacing_ss_ratio;
+ else
+ rate *= sysctl_tcp_pacing_ca_ratio;
rate *= max(tp->snd_cwnd, tp->packets_out);
* highest SACK block). Also calculate the lowest snd_nxt among the remaining
* retransmitted skbs to avoid some costly processing per ACKs.
*/
-static void tcp_mark_lost_retrans(struct sock *sk)
+static void tcp_mark_lost_retrans(struct sock *sk, int *flag)
{
const struct inet_connection_sock *icsk = inet_csk(sk);
struct tcp_sock *tp = tcp_sk(sk);
if (after(received_upto, ack_seq)) {
TCP_SKB_CB(skb)->sacked &= ~TCPCB_SACKED_RETRANS;
tp->retrans_out -= tcp_skb_pcount(skb);
-
+ *flag |= FLAG_LOST_RETRANS;
tcp_skb_mark_lost_uncond_verify(tp, skb);
NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPLOSTRETRANSMIT);
} else {
((inet_csk(sk)->icsk_ca_state != TCP_CA_Loss) || tp->undo_marker))
tcp_update_reordering(sk, tp->fackets_out - state->reord, 0);
- tcp_mark_lost_retrans(sk);
+ tcp_mark_lost_retrans(sk, &state->flag);
tcp_verify_left_out(tp);
out:
return false;
}
-/* The cwnd reduction in CWR and Recovery use the PRR algorithm
- * https://datatracker.ietf.org/doc/draft-ietf-tcpm-proportional-rate-reduction/
+/* The cwnd reduction in CWR and Recovery uses the PRR algorithm in RFC 6937.
* It computes the number of packets to send (sndcnt) based on packets newly
* delivered:
* 1) If the packets in flight is larger than ssthresh, PRR spreads the
* cwnd reductions across a full RTT.
- * 2) If packets in flight is lower than ssthresh (such as due to excess
- * losses and/or application stalls), do not perform any further cwnd
- * reductions, but instead slow start up to ssthresh.
+ * 2) Otherwise PRR uses packet conservation to send as much as delivered.
+ * But when the retransmits are acked without further losses, PRR
+ * slow starts cwnd up to ssthresh to speed up the recovery.
*/
static void tcp_init_cwnd_reduction(struct sock *sk)
{
}
static void tcp_cwnd_reduction(struct sock *sk, const int prior_unsacked,
- int fast_rexmit)
+ int fast_rexmit, int flag)
{
struct tcp_sock *tp = tcp_sk(sk);
int sndcnt = 0;
(tp->packets_out - tp->sacked_out);
tp->prr_delivered += newly_acked_sacked;
- if (tcp_packets_in_flight(tp) > tp->snd_ssthresh) {
+ if (delta < 0) {
u64 dividend = (u64)tp->snd_ssthresh * tp->prr_delivered +
tp->prior_cwnd - 1;
sndcnt = div_u64(dividend, tp->prior_cwnd) - tp->prr_out;
- } else {
+ } else if ((flag & FLAG_RETRANS_DATA_ACKED) &&
+ !(flag & FLAG_LOST_RETRANS)) {
sndcnt = min_t(int, delta,
max_t(int, tp->prr_delivered - tp->prr_out,
newly_acked_sacked) + 1);
+ } else {
+ sndcnt = min(delta, newly_acked_sacked);
}
-
sndcnt = max(sndcnt, (fast_rexmit ? 1 : 0));
tp->snd_cwnd = tcp_packets_in_flight(tp) + sndcnt;
}
if (inet_csk(sk)->icsk_ca_state != TCP_CA_CWR) {
tcp_try_keep_open(sk);
} else {
- tcp_cwnd_reduction(sk, prior_unsacked, 0);
+ tcp_cwnd_reduction(sk, prior_unsacked, 0, flag);
}
}
icsk->icsk_mtup.search_high = icsk->icsk_mtup.probe_size - 1;
icsk->icsk_mtup.probe_size = 0;
+ NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPMTUPFAIL);
}
static void tcp_mtup_probe_success(struct sock *sk)
icsk->icsk_mtup.search_low = icsk->icsk_mtup.probe_size;
icsk->icsk_mtup.probe_size = 0;
tcp_sync_mss(sk, icsk->icsk_pmtu_cookie);
+ NET_INC_STATS_BH(sock_net(sk), LINUX_MIB_TCPMTUPSUCCESS);
}
/* Do a simple retransmit without using the backoff mechanisms in
tp->prior_ssthresh = 0;
tcp_init_undo(tp);
- if (inet_csk(sk)->icsk_ca_state < TCP_CA_CWR) {
+ if (!tcp_in_cwnd_reduction(sk)) {
if (!ece_ack)
tp->prior_ssthresh = tcp_current_ssthresh(sk);
tcp_init_cwnd_reduction(sk);
/* Undo during fast recovery after partial ACK. */
static bool tcp_try_undo_partial(struct sock *sk, const int acked,
- const int prior_unsacked)
+ const int prior_unsacked, int flag)
{
struct tcp_sock *tp = tcp_sk(sk);
* mark more packets lost or retransmit more.
*/
if (tp->retrans_out) {
- tcp_cwnd_reduction(sk, prior_unsacked, 0);
+ tcp_cwnd_reduction(sk, prior_unsacked, 0, flag);
return true;
}
if (tcp_is_reno(tp) && is_dupack)
tcp_add_reno_sack(sk);
} else {
- if (tcp_try_undo_partial(sk, acked, prior_unsacked))
+ if (tcp_try_undo_partial(sk, acked, prior_unsacked, flag))
return;
/* Partial ACK arrived. Force fast retransmit. */
do_lost = tcp_is_reno(tp) ||
break;
case TCP_CA_Loss:
tcp_process_loss(sk, flag, is_dupack);
- if (icsk->icsk_ca_state != TCP_CA_Open)
+ if (icsk->icsk_ca_state != TCP_CA_Open &&
+ !(flag & FLAG_LOST_RETRANS))
return;
- /* Fall through to processing in Open state. */
+ /* Change state if cwnd is undone or retransmits are lost */
default:
if (tcp_is_reno(tp)) {
if (flag & FLAG_SND_UNA_ADVANCED)
if (do_lost)
tcp_update_scoreboard(sk, fast_rexmit);
- tcp_cwnd_reduction(sk, prior_unsacked, fast_rexmit);
+ tcp_cwnd_reduction(sk, prior_unsacked, fast_rexmit, flag);
tcp_xmit_retransmit_queue(sk);
}
}
/* Compute time elapsed between (last) SYNACK and the ACK completing 3WHS. */
-static void tcp_synack_rtt_meas(struct sock *sk, const u32 synack_stamp)
+void tcp_synack_rtt_meas(struct sock *sk, struct request_sock *req)
{
- struct tcp_sock *tp = tcp_sk(sk);
- long seq_rtt_us = -1L;
+ long rtt_us = -1L;
- if (synack_stamp && !tp->total_retrans)
- seq_rtt_us = jiffies_to_usecs(tcp_time_stamp - synack_stamp);
+ if (req && !req->num_retrans && tcp_rsk(req)->snt_synack.v64) {
+ struct skb_mstamp now;
- /* If the ACK acks both the SYNACK and the (Fast Open'd) data packets
- * sent in SYN_RECV, SYNACK RTT is the smooth RTT computed in tcp_ack()
- */
- if (!tp->srtt_us)
- tcp_ack_update_rtt(sk, FLAG_SYN_ACKED, seq_rtt_us, -1L);
+ skb_mstamp_get(&now);
+ rtt_us = skb_mstamp_us_delta(&now, &tcp_rsk(req)->snt_synack);
+ }
+
+ tcp_ack_update_rtt(sk, FLAG_SYN_ACKED, rtt_us, -1L);
}
+
static void tcp_cong_avoid(struct sock *sk, u32 ack, u32 acked)
{
const struct inet_connection_sock *icsk = inet_csk(sk);
tp->pred_flags = 0;
tcp_fast_path_check(sk);
+ if (tcp_send_head(sk))
+ tcp_slow_start_after_idle_check(sk);
+
if (nwin > tp->max_window) {
tp->max_window = nwin;
tcp_sync_mss(sk, inet_csk(sk)->icsk_pmtu_cookie);
&sack_state);
acked -= tp->packets_out;
- /* Advance cwnd if state allows */
- if (tcp_may_raise_cwnd(sk, flag))
- tcp_cong_avoid(sk, ack, acked);
-
if (tcp_ack_is_dubious(sk, flag)) {
is_dupack = !(flag & (FLAG_SND_UNA_ADVANCED | FLAG_NOT_DUP));
tcp_fastretrans_alert(sk, acked, prior_unsacked,
if (tp->tlp_high_seq)
tcp_process_tlp_ack(sk, ack, flag);
+ /* Advance cwnd if state allows */
+ if (tcp_may_raise_cwnd(sk, flag))
+ tcp_cong_avoid(sk, ack, acked);
+
if ((flag & FLAG_FORWARD_PROGRESS) || !(flag & FLAG_NOT_DUP)) {
struct dst_entry *dst = __sk_dst_get(sk);
if (dst)
static void tcp_fin(struct sock *sk)
{
struct tcp_sock *tp = tcp_sk(sk);
- const struct dst_entry *dst;
inet_csk_schedule_ack(sk);
case TCP_ESTABLISHED:
/* Move to CLOSE_WAIT */
tcp_set_state(sk, TCP_CLOSE_WAIT);
- dst = __sk_dst_get(sk);
- if (!dst || !dst_metric(dst, RTAX_QUICKACK))
- inet_csk(sk)->icsk_ack.pingpong = 1;
+ inet_csk(sk)->icsk_ack.pingpong = 1;
break;
case TCP_CLOSE_WAIT:
struct request_sock *req;
int queued = 0;
bool acceptable;
- u32 synack_stamp;
tp->rx_opt.saw_tstamp = 0;
if (!acceptable)
return 1;
+ if (!tp->srtt_us)
+ tcp_synack_rtt_meas(sk, req);
+
/* Once we leave TCP_SYN_RECV, we no longer need req
* so release it.
*/
if (req) {
- synack_stamp = tcp_rsk(req)->snt_synack;
tp->total_retrans = req->num_retrans;
reqsk_fastopen_remove(sk, req, false);
} else {
- synack_stamp = tp->lsndtime;
/* Make sure socket is routed, for correct metrics. */
icsk->icsk_af_ops->rebuild_header(sk);
tcp_init_congestion_control(sk);
tp->snd_una = TCP_SKB_CB(skb)->ack_seq;
tp->snd_wnd = ntohs(th->window) << tp->rx_opt.snd_wscale;
tcp_init_wl(tp, TCP_SKB_CB(skb)->seq);
- tcp_synack_rtt_meas(sk, synack_stamp);
if (tp->rx_opt.tstamp_ok)
tp->advmss -= TCPOLEN_TSTAMP_ALIGNED;
const struct net *net = sock_net(listen_sk);
bool th_ecn = th->ece && th->cwr;
bool ect, ecn_ok;
+ u32 ecn_ok_dst;
if (!th_ecn)
return;
ect = !INET_ECN_is_not_ect(TCP_SKB_CB(skb)->ip_dsfield);
- ecn_ok = net->ipv4.sysctl_tcp_ecn || dst_feature(dst, RTAX_FEATURE_ECN);
+ ecn_ok_dst = dst_feature(dst, DST_FEATURE_ECN_MASK);
+ ecn_ok = net->ipv4.sysctl_tcp_ecn || ecn_ok_dst;
- if ((!ect && ecn_ok) || tcp_ca_needs_ecn(listen_sk))
+ if ((!ect && ecn_ok) || tcp_ca_needs_ecn(listen_sk) ||
+ (ecn_ok_dst & DST_FEATURE_ECN_CA))
inet_rsk(req)->ecn_ok = 1;
}
req->cookie_ts = 0;
tcp_rsk(req)->rcv_isn = TCP_SKB_CB(skb)->seq;
tcp_rsk(req)->rcv_nxt = TCP_SKB_CB(skb)->seq + 1;
- tcp_rsk(req)->snt_synack = tcp_time_stamp;
+ skb_mstamp_get(&tcp_rsk(req)->snt_synack);
tcp_rsk(req)->last_oow_ack_time = 0;
req->mss = rx_opt->mss_clamp;
req->ts_recent = rx_opt->saw_tstamp ? rx_opt->rcv_tsval : 0;
}
tcp_rsk(req)->snt_isn = isn;
+ tcp_rsk(req)->txhash = net_tx_rndhash();
tcp_openreq_init_rwin(req, sk, dst);
fastopen = !want_cookie &&
tcp_try_fastopen(sk, skb, req, &foc, dst);
projects / cascardo / linux.git / blobdiff