Commit 32cf8edb authored by David Howells's avatar David Howells
Browse files

rxrpc: Trace/count transmission underflows and cwnd resets 



Add a tracepoint to log when a cwnd reset occurs due to lack of
transmission on a call.

Add stat counters to count transmission underflows (ie. when we have tx
window space, but sendmsg doesn't manage to keep up), cwnd resets and
transmission failures.

Signed-off-by: default avatarDavid Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org
parent 3dd9c8b5

include/trace/events/rxrpc.h

+38 −0
Original line number Diff line number Diff line
@@ -1446,6 +1446,44 @@ TRACE_EVENT(rxrpc_congest, 
		      __entry->sum.retrans_timeo ? " rTxTo" : "")

	    );



TRACE_EVENT(rxrpc_reset_cwnd,

	    TP_PROTO(struct rxrpc_call *call, ktime_t now),



	    TP_ARGS(call, now),



	    TP_STRUCT__entry(

		    __field(unsigned int,			call		)

		    __field(enum rxrpc_congest_mode,		mode		)

		    __field(unsigned short,			cwnd		)

		    __field(unsigned short,			extra		)

		    __field(rxrpc_seq_t,			hard_ack	)

		    __field(rxrpc_seq_t,			prepared	)

		    __field(ktime_t,				since_last_tx	)

		    __field(bool,				has_data	)

			     ),



	    TP_fast_assign(

		    __entry->call	= call->debug_id;

		    __entry->mode	= call->cong_mode;

		    __entry->cwnd	= call->cong_cwnd;

		    __entry->extra	= call->cong_extra;

		    __entry->hard_ack	= call->acks_hard_ack;

		    __entry->prepared	= call->tx_prepared - call->tx_bottom;

		    __entry->since_last_tx = ktime_sub(now, call->tx_last_sent);

		    __entry->has_data	= !list_empty(&call->tx_sendmsg);

			   ),



	    TP_printk("c=%08x q=%08x %s cw=%u+%u pr=%u tm=%llu d=%u",

		      __entry->call,

		      __entry->hard_ack,

		      __print_symbolic(__entry->mode, rxrpc_congest_modes),

		      __entry->cwnd,

		      __entry->extra,

		      __entry->prepared,

		      ktime_to_ns(__entry->since_last_tx),

		      __entry->has_data)

	    );



TRACE_EVENT(rxrpc_disconnect_call,

	    TP_PROTO(struct rxrpc_call *call),

net/rxrpc/ar-internal.h

+3 −0
Original line number Diff line number Diff line
@@ -101,6 +101,9 @@ struct rxrpc_net { 
	atomic_t		stat_tx_data_retrans;

	atomic_t		stat_tx_data_send;

	atomic_t		stat_tx_data_send_frag;

	atomic_t		stat_tx_data_send_fail;

	atomic_t		stat_tx_data_underflow;

	atomic_t		stat_tx_data_cwnd_reset;

	atomic_t		stat_rx_data;

	atomic_t		stat_rx_data_reqack;

	atomic_t		stat_rx_data_jumbo;

net/rxrpc/call_event.c

+3 −1
Original line number Diff line number Diff line
@@ -317,8 +317,10 @@ static void rxrpc_transmit_some_data(struct rxrpc_call *call) 
	case RXRPC_CALL_CLIENT_AWAIT_REPLY:

		if (!rxrpc_tx_window_has_space(call))

			return;

		if (list_empty(&call->tx_sendmsg))

		if (list_empty(&call->tx_sendmsg)) {

			rxrpc_inc_stat(call->rxnet, stat_tx_data_underflow);

			return;

		}

		rxrpc_decant_prepared_tx(call);

		break;

	default:

net/rxrpc/input.c

+5 −2
Original line number Diff line number Diff line
@@ -27,6 +27,7 @@ static void rxrpc_congestion_management(struct rxrpc_call *call, 
	enum rxrpc_congest_change change = rxrpc_cong_no_change;

	unsigned int cumulative_acks = call->cong_cumul_acks;

	unsigned int cwnd = call->cong_cwnd;

	ktime_t now;

	bool resend = false;



	summary->flight_size =
@@ -59,13 +60,15 @@ static void rxrpc_congestion_management(struct rxrpc_call *call, 
	/* If we haven't transmitted anything for >1RTT, we should reset the

	 * congestion management state.

	 */

	now = ktime_get_real();

	if ((call->cong_mode == RXRPC_CALL_SLOW_START ||

	     call->cong_mode == RXRPC_CALL_CONGEST_AVOIDANCE) &&

	    ktime_before(ktime_add_us(call->tx_last_sent,

				      call->peer->srtt_us >> 3),

			 ktime_get_real())

				      call->peer->srtt_us >> 3), now)

	    ) {

		trace_rxrpc_reset_cwnd(call, now);

		change = rxrpc_cong_idle_reset;

		rxrpc_inc_stat(call->rxnet, stat_tx_data_cwnd_reset);

		summary->mode = RXRPC_CALL_SLOW_START;

		if (RXRPC_TX_SMSS > 2190)

			summary->cwnd = 2;

net/rxrpc/output.c

+2 −0
Original line number Diff line number Diff line
@@ -485,6 +485,7 @@ int rxrpc_send_data_packet(struct rxrpc_call *call, struct rxrpc_txbuf *txb) 


	up_read(&conn->local->defrag_sem);

	if (ret < 0) {

		rxrpc_inc_stat(call->rxnet, stat_tx_data_send_fail);

		rxrpc_cancel_rtt_probe(call, serial, rtt_slot);

		trace_rxrpc_tx_fail(call->debug_id, serial, ret,

				    rxrpc_tx_point_call_data_nofrag);
@@ -567,6 +568,7 @@ int rxrpc_send_data_packet(struct rxrpc_call *call, struct rxrpc_txbuf *txb) 
	}



	if (ret < 0) {

		rxrpc_inc_stat(call->rxnet, stat_tx_data_send_fail);

		rxrpc_cancel_rtt_probe(call, serial, rtt_slot);

		trace_rxrpc_tx_fail(call->debug_id, serial, ret,

				    rxrpc_tx_point_call_data_frag);