diff options
Diffstat (limited to 'net')
-rw-r--r-- | net/rxrpc/ar-internal.h | 53 | ||||
-rw-r--r-- | net/rxrpc/call_event.c | 36 | ||||
-rw-r--r-- | net/rxrpc/call_object.c | 13 | ||||
-rw-r--r-- | net/rxrpc/conn_event.c | 1 | ||||
-rw-r--r-- | net/rxrpc/input.c | 169 | ||||
-rw-r--r-- | net/rxrpc/misc.c | 19 | ||||
-rw-r--r-- | net/rxrpc/output.c | 9 | ||||
-rw-r--r-- | net/rxrpc/sendmsg.c | 7 |
8 files changed, 294 insertions, 13 deletions
diff --git a/net/rxrpc/ar-internal.h b/net/rxrpc/ar-internal.h index b1e697fc9ffb..ca96e547cb9a 100644 --- a/net/rxrpc/ar-internal.h +++ b/net/rxrpc/ar-internal.h @@ -402,6 +402,7 @@ enum rxrpc_call_flag { RXRPC_CALL_RX_LAST, /* Received the last packet (at rxtx_top) */ RXRPC_CALL_TX_LAST, /* Last packet in Tx buffer (at rxtx_top) */ RXRPC_CALL_PINGING, /* Ping in process */ + RXRPC_CALL_RETRANS_TIMEOUT, /* Retransmission due to timeout occurred */ }; /* @@ -447,6 +448,17 @@ enum rxrpc_call_completion { }; /* + * Call Tx congestion management modes. + */ +enum rxrpc_congest_mode { + RXRPC_CALL_SLOW_START, + RXRPC_CALL_CONGEST_AVOIDANCE, + RXRPC_CALL_PACKET_LOSS, + RXRPC_CALL_FAST_RETRANSMIT, + NR__RXRPC_CONGEST_MODES +}; + +/* * RxRPC call definition * - matched by { connection, call_id } */ @@ -518,6 +530,20 @@ struct rxrpc_call { * not hard-ACK'd packet follows this. */ rxrpc_seq_t tx_top; /* Highest Tx slot allocated. */ + + /* TCP-style slow-start congestion control [RFC5681]. Since the SMSS + * is fixed, we keep these numbers in terms of segments (ie. DATA + * packets) rather than bytes. + */ +#define RXRPC_TX_SMSS RXRPC_JUMBO_DATALEN + u8 cong_cwnd; /* Congestion window size */ + u8 cong_extra; /* Extra to send for congestion management */ + u8 cong_ssthresh; /* Slow-start threshold */ + enum rxrpc_congest_mode cong_mode:8; /* Congestion management mode */ + u8 cong_dup_acks; /* Count of ACKs showing missing packets */ + u8 cong_cumul_acks; /* Cumulative ACK count */ + ktime_t cong_tstamp; /* Last time cwnd was changed */ + rxrpc_seq_t rx_hard_ack; /* Dead slot in buffer; the first received but not * consumed packet follows this. */ @@ -539,12 +565,13 @@ struct rxrpc_call { ktime_t ackr_ping_time; /* Time last ping sent */ /* transmission-phase ACK management */ + ktime_t acks_latest_ts; /* Timestamp of latest ACK received */ rxrpc_serial_t acks_latest; /* serial number of latest ACK received */ rxrpc_seq_t acks_lowest_nak; /* Lowest NACK in the buffer (or ==tx_hard_ack) */ }; /* - * Summary of a new ACK and the changes it made. + * Summary of a new ACK and the changes it made to the Tx buffer packet states. */ struct rxrpc_ack_summary { u8 ack_reason; @@ -554,6 +581,14 @@ struct rxrpc_ack_summary { u8 nr_new_nacks; /* Number of new NACKs in packet */ u8 nr_rot_new_acks; /* Number of rotated new ACKs */ bool new_low_nack; /* T if new low NACK found */ + bool retrans_timeo; /* T if reTx due to timeout happened */ + u8 flight_size; /* Number of unreceived transmissions */ + /* Place to stash values for tracing */ + enum rxrpc_congest_mode mode:8; + u8 cwnd; + u8 ssthresh; + u8 dup_acks; + u8 cumulative_acks; }; enum rxrpc_skb_trace { @@ -709,6 +744,7 @@ extern const char rxrpc_timer_traces[rxrpc_timer__nr_trace][8]; enum rxrpc_propose_ack_trace { rxrpc_propose_ack_client_tx_end, rxrpc_propose_ack_input_data, + rxrpc_propose_ack_ping_for_lost_ack, rxrpc_propose_ack_ping_for_lost_reply, rxrpc_propose_ack_ping_for_params, rxrpc_propose_ack_respond_to_ack, @@ -729,6 +765,21 @@ enum rxrpc_propose_ack_outcome { extern const char rxrpc_propose_ack_traces[rxrpc_propose_ack__nr_trace][8]; extern const char *const rxrpc_propose_ack_outcomes[rxrpc_propose_ack__nr_outcomes]; +enum rxrpc_congest_change { + rxrpc_cong_begin_retransmission, + rxrpc_cong_cleared_nacks, + rxrpc_cong_new_low_nack, + rxrpc_cong_no_change, + rxrpc_cong_progress, + rxrpc_cong_retransmit_again, + rxrpc_cong_rtt_window_end, + rxrpc_cong_saw_nack, + rxrpc_congest__nr_change +}; + +extern const char rxrpc_congest_modes[NR__RXRPC_CONGEST_MODES][10]; +extern const char rxrpc_congest_changes[rxrpc_congest__nr_change][9]; + extern const char *const rxrpc_pkts[]; extern const char const rxrpc_ack_names[RXRPC_ACK__INVALID + 1][4]; diff --git a/net/rxrpc/call_event.c b/net/rxrpc/call_event.c index 05b94d1acf52..0e8478012212 100644 --- a/net/rxrpc/call_event.c +++ b/net/rxrpc/call_event.c @@ -147,6 +147,14 @@ void rxrpc_propose_ACK(struct rxrpc_call *call, u8 ack_reason, } /* + * Handle congestion being detected by the retransmit timeout. + */ +static void rxrpc_congestion_timeout(struct rxrpc_call *call) +{ + set_bit(RXRPC_CALL_RETRANS_TIMEOUT, &call->flags); +} + +/* * Perform retransmission of NAK'd and unack'd packets. */ static void rxrpc_resend(struct rxrpc_call *call) @@ -154,9 +162,9 @@ static void rxrpc_resend(struct rxrpc_call *call) struct rxrpc_skb_priv *sp; struct sk_buff *skb; rxrpc_seq_t cursor, seq, top; - ktime_t now = ktime_get_real(), max_age, oldest, resend_at; + ktime_t now = ktime_get_real(), max_age, oldest, resend_at, ack_ts; int ix; - u8 annotation, anno_type; + u8 annotation, anno_type, retrans = 0, unacked = 0; _enter("{%d,%d}", call->tx_hard_ack, call->tx_top); @@ -193,10 +201,13 @@ static void rxrpc_resend(struct rxrpc_call *call) oldest = skb->tstamp; continue; } + if (!(annotation & RXRPC_TX_ANNO_RESENT)) + unacked++; } /* Okay, we need to retransmit a packet. */ call->rxtx_annotations[ix] = RXRPC_TX_ANNO_RETRANS | annotation; + retrans++; trace_rxrpc_retransmit(call, seq, annotation | anno_type, ktime_to_ns(ktime_sub(skb->tstamp, max_age))); } @@ -210,6 +221,25 @@ static void rxrpc_resend(struct rxrpc_call *call) * reached the nsec timeout yet. */ + if (unacked) + rxrpc_congestion_timeout(call); + + /* If there was nothing that needed retransmission then it's likely + * that an ACK got lost somewhere. Send a ping to find out instead of + * retransmitting data. + */ + if (!retrans) { + rxrpc_set_timer(call, rxrpc_timer_set_for_resend); + spin_unlock_bh(&call->lock); + ack_ts = ktime_sub(now, call->acks_latest_ts); + if (ktime_to_ns(ack_ts) < call->peer->rtt) + goto out; + rxrpc_propose_ACK(call, RXRPC_ACK_PING, 0, 0, true, false, + rxrpc_propose_ack_ping_for_lost_ack); + rxrpc_send_call_packet(call, RXRPC_PACKET_TYPE_ACK); + goto out; + } + /* Now go through the Tx window and perform the retransmissions. We * have to drop the lock for each send. If an ACK comes in whilst the * lock is dropped, it may clear some of the retransmission markers for @@ -260,6 +290,7 @@ static void rxrpc_resend(struct rxrpc_call *call) out_unlock: spin_unlock_bh(&call->lock); +out: _leave(""); } @@ -293,6 +324,7 @@ recheck_state: if (time_after_eq(now, call->expire_at)) { rxrpc_abort_call("EXP", call, 0, RX_CALL_TIMEOUT, ETIME); set_bit(RXRPC_CALL_EV_ABORT, &call->events); + goto recheck_state; } if (test_and_clear_bit(RXRPC_CALL_EV_ACK, &call->events) || diff --git a/net/rxrpc/call_object.c b/net/rxrpc/call_object.c index a53f4c2c0025..d4b3293b78fa 100644 --- a/net/rxrpc/call_object.c +++ b/net/rxrpc/call_object.c @@ -160,6 +160,14 @@ struct rxrpc_call *rxrpc_alloc_call(gfp_t gfp) call->rx_winsize = rxrpc_rx_window_size; call->tx_winsize = 16; call->rx_expect_next = 1; + + if (RXRPC_TX_SMSS > 2190) + call->cong_cwnd = 2; + else if (RXRPC_TX_SMSS > 1095) + call->cong_cwnd = 3; + else + call->cong_cwnd = 4; + call->cong_ssthresh = RXRPC_RXTX_BUFF_SIZE - 1; return call; nomem_2: @@ -176,6 +184,7 @@ static struct rxrpc_call *rxrpc_alloc_client_call(struct sockaddr_rxrpc *srx, gfp_t gfp) { struct rxrpc_call *call; + ktime_t now; _enter(""); @@ -185,6 +194,9 @@ static struct rxrpc_call *rxrpc_alloc_client_call(struct sockaddr_rxrpc *srx, call->state = RXRPC_CALL_CLIENT_AWAIT_CONN; call->service_id = srx->srx_service; call->tx_phase = true; + now = ktime_get_real(); + call->acks_latest_ts = now; + call->cong_tstamp = now; _leave(" = %p", call); return call; @@ -325,6 +337,7 @@ void rxrpc_incoming_call(struct rxrpc_sock *rx, call->state = RXRPC_CALL_SERVER_ACCEPTING; if (sp->hdr.securityIndex > 0) call->state = RXRPC_CALL_SERVER_SECURING; + call->cong_tstamp = skb->tstamp; /* Set the channel for this call. We don't get channel_lock as we're * only defending against the data_ready handler (which we're called diff --git a/net/rxrpc/conn_event.c b/net/rxrpc/conn_event.c index a1cf1ec5f29e..37609ce89f52 100644 --- a/net/rxrpc/conn_event.c +++ b/net/rxrpc/conn_event.c @@ -97,6 +97,7 @@ static void rxrpc_conn_retransmit_call(struct rxrpc_connection *conn, pkt.info.maxMTU = htonl(mtu); pkt.info.rwind = htonl(rxrpc_rx_window_size); pkt.info.jumbo_max = htonl(rxrpc_rx_jumbo_max); + pkt.whdr.flags |= RXRPC_SLOW_START_OK; len += sizeof(pkt.ack) + sizeof(pkt.info); break; } diff --git a/net/rxrpc/input.c b/net/rxrpc/input.c index 0344f4494eb7..094720dd1eaf 100644 --- a/net/rxrpc/input.c +++ b/net/rxrpc/input.c @@ -37,6 +37,166 @@ static void rxrpc_proto_abort(const char *why, } /* + * Do TCP-style congestion management [RFC 5681]. + */ +static void rxrpc_congestion_management(struct rxrpc_call *call, + struct sk_buff *skb, + struct rxrpc_ack_summary *summary) +{ + enum rxrpc_congest_change change = rxrpc_cong_no_change; + struct rxrpc_skb_priv *sp = rxrpc_skb(skb); + unsigned int cumulative_acks = call->cong_cumul_acks; + unsigned int cwnd = call->cong_cwnd; + bool resend = false; + + summary->flight_size = + (call->tx_top - call->tx_hard_ack) - summary->nr_acks; + + if (test_and_clear_bit(RXRPC_CALL_RETRANS_TIMEOUT, &call->flags)) { + summary->retrans_timeo = true; + call->cong_ssthresh = max_t(unsigned int, + summary->flight_size / 2, 2); + cwnd = 1; + if (cwnd > call->cong_ssthresh && + call->cong_mode == RXRPC_CALL_SLOW_START) { + call->cong_mode = RXRPC_CALL_CONGEST_AVOIDANCE; + call->cong_tstamp = skb->tstamp; + cumulative_acks = 0; + } + } + + cumulative_acks += summary->nr_new_acks; + cumulative_acks += summary->nr_rot_new_acks; + if (cumulative_acks > 255) + cumulative_acks = 255; + + summary->mode = call->cong_mode; + summary->cwnd = call->cong_cwnd; + summary->ssthresh = call->cong_ssthresh; + summary->cumulative_acks = cumulative_acks; + summary->dup_acks = call->cong_dup_acks; + + switch (call->cong_mode) { + case RXRPC_CALL_SLOW_START: + if (summary->nr_nacks > 0) + goto packet_loss_detected; + if (summary->cumulative_acks > 0) + cwnd += 1; + if (cwnd > call->cong_ssthresh) { + call->cong_mode = RXRPC_CALL_CONGEST_AVOIDANCE; + call->cong_tstamp = skb->tstamp; + } + goto out; + + case RXRPC_CALL_CONGEST_AVOIDANCE: + if (summary->nr_nacks > 0) + goto packet_loss_detected; + + /* We analyse the number of packets that get ACK'd per RTT + * period and increase the window if we managed to fill it. + */ + if (call->peer->rtt_usage == 0) + goto out; + if (ktime_before(skb->tstamp, + ktime_add_ns(call->cong_tstamp, + call->peer->rtt))) + goto out_no_clear_ca; + change = rxrpc_cong_rtt_window_end; + call->cong_tstamp = skb->tstamp; + if (cumulative_acks >= cwnd) + cwnd++; + goto out; + + case RXRPC_CALL_PACKET_LOSS: + if (summary->nr_nacks == 0) + goto resume_normality; + + if (summary->new_low_nack) { + change = rxrpc_cong_new_low_nack; + call->cong_dup_acks = 1; + if (call->cong_extra > 1) + call->cong_extra = 1; + goto send_extra_data; + } + + call->cong_dup_acks++; + if (call->cong_dup_acks < 3) + goto send_extra_data; + + change = rxrpc_cong_begin_retransmission; + call->cong_mode = RXRPC_CALL_FAST_RETRANSMIT; + call->cong_ssthresh = max_t(unsigned int, + summary->flight_size / 2, 2); + cwnd = call->cong_ssthresh + 3; + call->cong_extra = 0; + call->cong_dup_acks = 0; + resend = true; + goto out; + + case RXRPC_CALL_FAST_RETRANSMIT: + if (!summary->new_low_nack) { + if (summary->nr_new_acks == 0) + cwnd += 1; + call->cong_dup_acks++; + if (call->cong_dup_acks == 2) { + change = rxrpc_cong_retransmit_again; + call->cong_dup_acks = 0; + resend = true; + } + } else { + change = rxrpc_cong_progress; + cwnd = call->cong_ssthresh; + if (summary->nr_nacks == 0) + goto resume_normality; + } + goto out; + + default: + BUG(); + goto out; + } + +resume_normality: + change = rxrpc_cong_cleared_nacks; + call->cong_dup_acks = 0; + call->cong_extra = 0; + call->cong_tstamp = skb->tstamp; + if (cwnd <= call->cong_ssthresh) + call->cong_mode = RXRPC_CALL_SLOW_START; + else + call->cong_mode = RXRPC_CALL_CONGEST_AVOIDANCE; +out: + cumulative_acks = 0; +out_no_clear_ca: + if (cwnd >= RXRPC_RXTX_BUFF_SIZE - 1) + cwnd = RXRPC_RXTX_BUFF_SIZE - 1; + call->cong_cwnd = cwnd; + call->cong_cumul_acks = cumulative_acks; + trace_rxrpc_congest(call, summary, sp->hdr.serial, change); + if (resend && !test_and_set_bit(RXRPC_CALL_EV_RESEND, &call->events)) + rxrpc_queue_call(call); + return; + +packet_loss_detected: + change = rxrpc_cong_saw_nack; + call->cong_mode = RXRPC_CALL_PACKET_LOSS; + call->cong_dup_acks = 0; + goto send_extra_data; + +send_extra_data: + /* Send some previously unsent DATA if we have some to advance the ACK + * state. + */ + if (call->rxtx_annotations[call->tx_top & RXRPC_RXTX_BUFF_MASK] & + RXRPC_TX_ANNO_LAST || + summary->nr_acks != call->tx_top - call->tx_hard_ack) { + call->cong_extra++; + wake_up(&call->waitq); + } + goto out_no_clear_ca; +} + +/* * Ping the other end to fill our RTT cache and to retrieve the rwind * and MTU parameters. */ @@ -524,7 +684,6 @@ static void rxrpc_input_soft_acks(struct rxrpc_call *call, u8 *acks, rxrpc_seq_t seq, int nr_acks, struct rxrpc_ack_summary *summary) { - bool resend = false; int ix; u8 annotation, anno_type; @@ -556,16 +715,11 @@ static void rxrpc_input_soft_acks(struct rxrpc_call *call, u8 *acks, continue; call->rxtx_annotations[ix] = RXRPC_TX_ANNO_NAK | annotation; - resend = true; break; default: return rxrpc_proto_abort("SFT", call, 0); } } - - if (resend && - !test_and_set_bit(RXRPC_CALL_EV_RESEND, &call->events)) - rxrpc_queue_call(call); } /* @@ -663,6 +817,7 @@ static void rxrpc_input_ack(struct rxrpc_call *call, struct sk_buff *skb, sp->hdr.serial, call->acks_latest); return; } + call->acks_latest_ts = skb->tstamp; call->acks_latest = sp->hdr.serial; if (before(hard_ack, call->tx_hard_ack) || @@ -692,6 +847,8 @@ static void rxrpc_input_ack(struct rxrpc_call *call, struct sk_buff *skb, rxrpc_propose_ACK(call, RXRPC_ACK_PING, skew, sp->hdr.serial, false, true, rxrpc_propose_ack_ping_for_lost_reply); + + return rxrpc_congestion_management(call, skb, &summary); } /* diff --git a/net/rxrpc/misc.c b/net/rxrpc/misc.c index a608769343e6..aedb8978226d 100644 --- a/net/rxrpc/misc.c +++ b/net/rxrpc/misc.c @@ -200,6 +200,7 @@ const char rxrpc_timer_traces[rxrpc_timer__nr_trace][8] = { const char rxrpc_propose_ack_traces[rxrpc_propose_ack__nr_trace][8] = { [rxrpc_propose_ack_client_tx_end] = "ClTxEnd", [rxrpc_propose_ack_input_data] = "DataIn ", + [rxrpc_propose_ack_ping_for_lost_ack] = "LostAck", [rxrpc_propose_ack_ping_for_lost_reply] = "LostRpl", [rxrpc_propose_ack_ping_for_params] = "Params ", [rxrpc_propose_ack_respond_to_ack] = "Rsp2Ack", @@ -214,3 +215,21 @@ const char *const rxrpc_propose_ack_outcomes[rxrpc_propose_ack__nr_outcomes] = { [rxrpc_propose_ack_update] = " Update", [rxrpc_propose_ack_subsume] = " Subsume", }; + +const char rxrpc_congest_modes[NR__RXRPC_CONGEST_MODES][10] = { + [RXRPC_CALL_SLOW_START] = "SlowStart", + [RXRPC_CALL_CONGEST_AVOIDANCE] = "CongAvoid", + [RXRPC_CALL_PACKET_LOSS] = "PktLoss ", + [RXRPC_CALL_FAST_RETRANSMIT] = "FastReTx ", +}; + +const char rxrpc_congest_changes[rxrpc_congest__nr_change][9] = { + [rxrpc_cong_begin_retransmission] = " Retrans", + [rxrpc_cong_cleared_nacks] = " Cleared", + [rxrpc_cong_new_low_nack] = " NewLowN", + [rxrpc_cong_no_change] = "", + [rxrpc_cong_progress] = " Progres", + [rxrpc_cong_retransmit_again] = " ReTxAgn", + [rxrpc_cong_rtt_window_end] = " RttWinE", + [rxrpc_cong_saw_nack] = " SawNack", +}; diff --git a/net/rxrpc/output.c b/net/rxrpc/output.c index 3eb01445e814..cf43a715685e 100644 --- a/net/rxrpc/output.c +++ b/net/rxrpc/output.c @@ -157,6 +157,8 @@ int rxrpc_send_call_packet(struct rxrpc_call *call, u8 type) spin_unlock_bh(&call->lock); + pkt->whdr.flags |= RXRPC_SLOW_START_OK; + iov[0].iov_len += sizeof(pkt->ack) + n; iov[1].iov_base = &pkt->ackinfo; iov[1].iov_len = sizeof(pkt->ackinfo); @@ -276,8 +278,11 @@ int rxrpc_send_data_packet(struct rxrpc_call *call, struct sk_buff *skb) msg.msg_controllen = 0; msg.msg_flags = 0; - /* If our RTT cache needs working on, request an ACK. */ - if ((call->peer->rtt_usage < 3 && sp->hdr.seq & 1) || + /* If our RTT cache needs working on, request an ACK. Also request + * ACKs if a DATA packet appears to have been lost. + */ + if (call->cong_mode == RXRPC_CALL_FAST_RETRANSMIT || + (call->peer->rtt_usage < 3 && sp->hdr.seq & 1) || ktime_before(ktime_add_ms(call->peer->rtt_last_req, 1000), ktime_get_real())) whdr.flags |= RXRPC_REQUEST_ACK; diff --git a/net/rxrpc/sendmsg.c b/net/rxrpc/sendmsg.c index 99939372b5a4..1f8040d82395 100644 --- a/net/rxrpc/sendmsg.c +++ b/net/rxrpc/sendmsg.c @@ -45,7 +45,9 @@ static int rxrpc_wait_for_tx_window(struct rxrpc_sock *rx, for (;;) { set_current_state(TASK_INTERRUPTIBLE); ret = 0; - if (call->tx_top - call->tx_hard_ack < call->tx_winsize) + if (call->tx_top - call->tx_hard_ack < + min_t(unsigned int, call->tx_winsize, + call->cong_cwnd + call->cong_extra)) break; if (call->state >= RXRPC_CALL_COMPLETE) { ret = -call->error; @@ -203,7 +205,8 @@ static int rxrpc_send_data(struct rxrpc_sock *rx, _debug("alloc"); if (call->tx_top - call->tx_hard_ack >= - call->tx_winsize) { + min_t(unsigned int, call->tx_winsize, + call->cong_cwnd + call->cong_extra)) { ret = -EAGAIN; if (msg->msg_flags & MSG_DONTWAIT) goto maybe_error; |