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Miller" , Eric Dumazet , Jakub Kicinski , Paolo Abeni , linux-afs@lists.infradead.org, linux-kernel@vger.kernel.org Subject: [PATCH net-next v2 19/21] rxrpc: Record probes after transmission and reduce number of time-gets Date: Mon, 4 Mar 2024 08:43:16 +0000 Message-ID: <20240304084322.705539-20-dhowells@redhat.com> In-Reply-To: <20240304084322.705539-1-dhowells@redhat.com> References: <20240304084322.705539-1-dhowells@redhat.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Scanned-By: MIMEDefang 3.4.1 on 10.11.54.10 X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: 1792585007760718211 X-GMAIL-MSGID: 1792585007760718211 Move the recording of a successfully transmitted DATA or ACK packet that will provide RTT probing to after the transmission. With the I/O thread model, this can be done because parsing of the responding ACK can no longer race with the post-transmission code. Move the various timeout-settings done after successfully transmitting a DATA packet into rxrpc_tstamp_data_packets() and eliminate a number of calls to get the current time. As a consequence we no longer need to cancel a proposed RTT probe on transmission failure. Signed-off-by: David Howells cc: Marc Dionne cc: "David S. Miller" cc: Eric Dumazet cc: Jakub Kicinski cc: Paolo Abeni cc: linux-afs@lists.infradead.org cc: netdev@vger.kernel.org --- net/rxrpc/output.c | 105 +++++++++++++++++---------------------------- 1 file changed, 40 insertions(+), 65 deletions(-) diff --git a/net/rxrpc/output.c b/net/rxrpc/output.c index ec82193e5681..5ea9601efd05 100644 --- a/net/rxrpc/output.c +++ b/net/rxrpc/output.c @@ -63,7 +63,7 @@ static void rxrpc_tx_backoff(struct rxrpc_call *call, int ret) * Receiving a response to the ping will prevent the ->expect_rx_by timer from * expiring. */ -static void rxrpc_set_keepalive(struct rxrpc_call *call) +static void rxrpc_set_keepalive(struct rxrpc_call *call, ktime_t now) { ktime_t delay = ms_to_ktime(READ_ONCE(call->next_rx_timo) / 6); @@ -147,8 +147,8 @@ static void rxrpc_fill_out_ack(struct rxrpc_call *call, /* * Record the beginning of an RTT probe. */ -static int rxrpc_begin_rtt_probe(struct rxrpc_call *call, rxrpc_serial_t serial, - enum rxrpc_rtt_tx_trace why) +static void rxrpc_begin_rtt_probe(struct rxrpc_call *call, rxrpc_serial_t serial, + ktime_t now, enum rxrpc_rtt_tx_trace why) { unsigned long avail = call->rtt_avail; int rtt_slot = 9; @@ -161,30 +161,15 @@ static int rxrpc_begin_rtt_probe(struct rxrpc_call *call, rxrpc_serial_t serial, goto no_slot; call->rtt_serial[rtt_slot] = serial; - call->rtt_sent_at[rtt_slot] = ktime_get_real(); + call->rtt_sent_at[rtt_slot] = now; smp_wmb(); /* Write data before avail bit */ set_bit(rtt_slot + RXRPC_CALL_RTT_PEND_SHIFT, &call->rtt_avail); trace_rxrpc_rtt_tx(call, why, rtt_slot, serial); - return rtt_slot; + return; no_slot: trace_rxrpc_rtt_tx(call, rxrpc_rtt_tx_no_slot, rtt_slot, serial); - return -1; -} - -/* - * Cancel an RTT probe. - */ -static void rxrpc_cancel_rtt_probe(struct rxrpc_call *call, - rxrpc_serial_t serial, int rtt_slot) -{ - if (rtt_slot != -1) { - clear_bit(rtt_slot + RXRPC_CALL_RTT_PEND_SHIFT, &call->rtt_avail); - smp_wmb(); /* Clear pending bit before setting slot */ - set_bit(rtt_slot, &call->rtt_avail); - trace_rxrpc_rtt_tx(call, rxrpc_rtt_tx_cancel, rtt_slot, serial); - } } /* @@ -196,7 +181,8 @@ static void rxrpc_send_ack_packet(struct rxrpc_call *call, struct rxrpc_txbuf *t struct rxrpc_connection *conn; struct rxrpc_ackpacket *ack = (struct rxrpc_ackpacket *)(whdr + 1); struct msghdr msg; - int ret, rtt_slot = -1; + ktime_t now; + int ret; if (test_bit(RXRPC_CALL_DISCONNECTED, &call->flags)) return; @@ -218,9 +204,6 @@ static void rxrpc_send_ack_packet(struct rxrpc_call *call, struct rxrpc_txbuf *t ntohl(ack->serial), ack->reason, ack->nAcks, txb->ack_rwind); - if (ack->reason == RXRPC_ACK_PING) - rtt_slot = rxrpc_begin_rtt_probe(call, txb->serial, rxrpc_rtt_tx_ping); - rxrpc_inc_stat(call->rxnet, stat_tx_ack_send); iov_iter_kvec(&msg.msg_iter, WRITE, txb->kvec, txb->nr_kvec, txb->len); @@ -233,16 +216,14 @@ static void rxrpc_send_ack_packet(struct rxrpc_call *call, struct rxrpc_txbuf *t } else { trace_rxrpc_tx_packet(call->debug_id, whdr, rxrpc_tx_point_call_ack); + now = ktime_get_real(); + if (ack->reason == RXRPC_ACK_PING) + rxrpc_begin_rtt_probe(call, txb->serial, now, rxrpc_rtt_tx_ping); if (txb->flags & RXRPC_REQUEST_ACK) - call->peer->rtt_last_req = ktime_get_real(); + call->peer->rtt_last_req = now; + rxrpc_set_keepalive(call, now); } rxrpc_tx_backoff(call, ret); - - if (!__rxrpc_call_is_complete(call)) { - if (ret < 0) - rxrpc_cancel_rtt_probe(call, txb->serial, rtt_slot); - rxrpc_set_keepalive(call); - } } /* @@ -413,18 +394,36 @@ static size_t rxrpc_prepare_data_packet(struct rxrpc_call *call, struct rxrpc_tx } /* - * Set the times on a packet before transmission + * Set timeouts after transmitting a packet. */ -static int rxrpc_tstamp_data_packets(struct rxrpc_call *call, struct rxrpc_txbuf *txb) +static void rxrpc_tstamp_data_packets(struct rxrpc_call *call, struct rxrpc_txbuf *txb) { - ktime_t tstamp = ktime_get_real(); - int rtt_slot = -1; + ktime_t now = ktime_get_real(); + bool ack_requested = txb->flags & RXRPC_REQUEST_ACK; - txb->last_sent = tstamp; - if (txb->flags & RXRPC_REQUEST_ACK) - rtt_slot = rxrpc_begin_rtt_probe(call, txb->serial, rxrpc_rtt_tx_data); + call->tx_last_sent = now; + txb->last_sent = now; + + if (ack_requested) { + rxrpc_begin_rtt_probe(call, txb->serial, now, rxrpc_rtt_tx_data); + + call->peer->rtt_last_req = now; + if (call->peer->rtt_count > 1) { + ktime_t delay = rxrpc_get_rto_backoff(call->peer, false); - return rtt_slot; + call->ack_lost_at = ktime_add(now, delay); + trace_rxrpc_timer_set(call, delay, rxrpc_timer_trace_lost_ack); + } + } + + if (!test_and_set_bit(RXRPC_CALL_BEGAN_RX_TIMER, &call->flags)) { + ktime_t delay = ms_to_ktime(READ_ONCE(call->next_rx_timo)); + + call->expect_rx_by = ktime_add(now, delay); + trace_rxrpc_timer_set(call, delay, rxrpc_timer_trace_expect_rx); + } + + rxrpc_set_keepalive(call, now); } /* @@ -437,7 +436,7 @@ static int rxrpc_send_data_packet(struct rxrpc_call *call, struct rxrpc_txbuf *t enum rxrpc_tx_point frag; struct msghdr msg; size_t len; - int ret, rtt_slot = -1; + int ret; _enter("%x,{%d}", txb->seq, txb->len); @@ -479,8 +478,6 @@ static int rxrpc_send_data_packet(struct rxrpc_call *call, struct rxrpc_txbuf *t } retry: - rtt_slot = rxrpc_tstamp_data_packets(call, txb); - /* send the packet by UDP * - returns -EMSGSIZE if UDP would have to fragment the packet * to go out of the interface @@ -493,7 +490,6 @@ static int rxrpc_send_data_packet(struct rxrpc_call *call, struct rxrpc_txbuf *t if (ret < 0) { rxrpc_inc_stat(call->rxnet, stat_tx_data_send_fail); - rxrpc_cancel_rtt_probe(call, txb->serial, rtt_slot); trace_rxrpc_tx_fail(call->debug_id, txb->serial, ret, frag); } else { trace_rxrpc_tx_packet(call->debug_id, whdr, frag); @@ -508,28 +504,7 @@ static int rxrpc_send_data_packet(struct rxrpc_call *call, struct rxrpc_txbuf *t done: if (ret >= 0) { - call->tx_last_sent = txb->last_sent; - if (txb->flags & RXRPC_REQUEST_ACK) { - call->peer->rtt_last_req = txb->last_sent; - if (call->peer->rtt_count > 1) { - ktime_t delay = rxrpc_get_rto_backoff(call->peer, false); - ktime_t now = ktime_get_real(); - - call->ack_lost_at = ktime_add(now, delay); - trace_rxrpc_timer_set(call, delay, rxrpc_timer_trace_lost_ack); - } - } - - if (txb->seq == 1 && - !test_and_set_bit(RXRPC_CALL_BEGAN_RX_TIMER, - &call->flags)) { - ktime_t delay = ms_to_ktime(READ_ONCE(call->next_rx_timo)); - - call->expect_rx_by = ktime_add(ktime_get_real(), delay); - trace_rxrpc_timer_set(call, delay, rxrpc_timer_trace_expect_rx); - } - - rxrpc_set_keepalive(call); + rxrpc_tstamp_data_packets(call, txb); } else { /* Cancel the call if the initial transmission fails, * particularly if that's due to network routing issues that