diff options
| author | David Howells <dhowells@redhat.com> | 2016-09-24 20:05:27 +0300 |
|---|---|---|
| committer | David Howells <dhowells@redhat.com> | 2016-09-25 01:49:46 +0300 |
| commit | 57494343cb5d66962bb197878fb1cc576177db31 (patch) | |
| tree | 97da848d2149916a2ff1f410fc912e139991a56e /include/trace | |
| parent | 0d967960d39ee89f9e0289692e9f7232f490e55c (diff) | |
| download | linux-57494343cb5d66962bb197878fb1cc576177db31.tar.xz | |
rxrpc: Implement slow-start
Implement RxRPC slow-start, which is similar to RFC 5681 for TCP. A
tracepoint is added to log the state of the congestion management algorithm
and the decisions it makes.
Notes:
(1) Since we send fixed-size DATA packets (apart from the final packet in
each phase), counters and calculations are in terms of packets rather
than bytes.
(2) The ACK packet carries the equivalent of TCP SACK.
(3) The FLIGHT_SIZE calculation in RFC 5681 doesn't seem particularly
suited to SACK of a small number of packets. It seems that, almost
inevitably, by the time three 'duplicate' ACKs have been seen, we have
narrowed the loss down to one or two missing packets, and the
FLIGHT_SIZE calculation ends up as 2.
(4) In rxrpc_resend(), if there was no data that apparently needed
retransmission, we transmit a PING ACK to ask the peer to tell us what
its Rx window state is.
Signed-off-by: David Howells <dhowells@redhat.com>
Diffstat (limited to 'include/trace')
| -rw-r--r-- | include/trace/events/rxrpc.h | 45 |
1 files changed, 45 insertions, 0 deletions
diff --git a/include/trace/events/rxrpc.h b/include/trace/events/rxrpc.h index 56475497043d..ada12d00118c 100644 --- a/include/trace/events/rxrpc.h +++ b/include/trace/events/rxrpc.h @@ -570,6 +570,51 @@ TRACE_EVENT(rxrpc_retransmit, __entry->expiry) ); +TRACE_EVENT(rxrpc_congest, + TP_PROTO(struct rxrpc_call *call, struct rxrpc_ack_summary *summary, + rxrpc_serial_t ack_serial, enum rxrpc_congest_change change), + + TP_ARGS(call, summary, ack_serial, change), + + TP_STRUCT__entry( + __field(struct rxrpc_call *, call ) + __field(enum rxrpc_congest_change, change ) + __field(rxrpc_seq_t, hard_ack ) + __field(rxrpc_seq_t, top ) + __field(rxrpc_seq_t, lowest_nak ) + __field(rxrpc_serial_t, ack_serial ) + __field_struct(struct rxrpc_ack_summary, sum ) + ), + + TP_fast_assign( + __entry->call = call; + __entry->change = change; + __entry->hard_ack = call->tx_hard_ack; + __entry->top = call->tx_top; + __entry->lowest_nak = call->acks_lowest_nak; + __entry->ack_serial = ack_serial; + memcpy(&__entry->sum, summary, sizeof(__entry->sum)); + ), + + TP_printk("c=%p %08x %s %08x %s cw=%u ss=%u nr=%u,%u nw=%u,%u r=%u b=%u u=%u d=%u l=%x%s%s%s", + __entry->call, + __entry->ack_serial, + rxrpc_ack_names[__entry->sum.ack_reason], + __entry->hard_ack, + rxrpc_congest_modes[__entry->sum.mode], + __entry->sum.cwnd, + __entry->sum.ssthresh, + __entry->sum.nr_acks, __entry->sum.nr_nacks, + __entry->sum.nr_new_acks, __entry->sum.nr_new_nacks, + __entry->sum.nr_rot_new_acks, + __entry->top - __entry->hard_ack, + __entry->sum.cumulative_acks, + __entry->sum.dup_acks, + __entry->lowest_nak, __entry->sum.new_low_nack ? "!" : "", + rxrpc_congest_changes[__entry->change], + __entry->sum.retrans_timeo ? " rTxTo" : "") + ); + #endif /* _TRACE_RXRPC_H */ /* This part must be outside protection */ |