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rxrpc: Trace/count transmission underflows and cwnd resets

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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: David Howells <dhowells@redhat.com>
cc: Marc Dionne <marc.dionne@auristor.com>
cc: linux-afs@lists.infradead.org
This commit is contained in:
David Howells 2022-11-11 13:47:35 +00:00
parent 3dd9c8b5f0
commit 32cf8edb07
6 changed files with 61 additions and 7 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

38
include/trace/events/rxrpc.h
View file

@ -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),

3
net/rxrpc/ar-internal.h
View file

@ -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;

4
net/rxrpc/call_event.c
View file

@ -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:

7
net/rxrpc/input.c
View file

@ -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;

2
net/rxrpc/output.c
View file

@ -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);

14
net/rxrpc/proc.c
View file

@ -398,13 +398,16 @@ int rxrpc_stats_show(struct seq_file *seq, void *v)
struct rxrpc_net *rxnet = rxrpc_net(seq_file_single_net(seq));
seq_printf(seq,
"Data : send=%u sendf=%u\n",
"Data : send=%u sendf=%u fail=%u\n",
atomic_read(&rxnet->stat_tx_data_send),
atomic_read(&rxnet->stat_tx_data_send_frag));
atomic_read(&rxnet->stat_tx_data_send_frag),
atomic_read(&rxnet->stat_tx_data_send_fail));
seq_printf(seq,
"Data-Tx : nr=%u retrans=%u\n",
"Data-Tx : nr=%u retrans=%u uf=%u cwr=%u\n",
atomic_read(&rxnet->stat_tx_data),
atomic_read(&rxnet->stat_tx_data_retrans));
atomic_read(&rxnet->stat_tx_data_retrans),
atomic_read(&rxnet->stat_tx_data_underflow),
atomic_read(&rxnet->stat_tx_data_cwnd_reset));
seq_printf(seq,
"Data-Rx : nr=%u reqack=%u jumbo=%u\n",
atomic_read(&rxnet->stat_rx_data),
@ -472,8 +475,11 @@ int rxrpc_stats_clear(struct file *file, char *buf, size_t size)
atomic_set(&rxnet->stat_tx_data, 0);
atomic_set(&rxnet->stat_tx_data_retrans, 0);
atomic_set(&rxnet->stat_tx_data_underflow, 0);
atomic_set(&rxnet->stat_tx_data_cwnd_reset, 0);
atomic_set(&rxnet->stat_tx_data_send, 0);
atomic_set(&rxnet->stat_tx_data_send_frag, 0);
atomic_set(&rxnet->stat_tx_data_send_fail, 0);
atomic_set(&rxnet->stat_rx_data, 0);
atomic_set(&rxnet->stat_rx_data_reqack, 0);
atomic_set(&rxnet->stat_rx_data_jumbo, 0);