From cf1a6474f80735ff4a5d99f3dd68a94dbec8455f Mon Sep 17 00:00:00 2001 From: David Howells Date: Thu, 22 Sep 2016 00:41:53 +0100 Subject: [PATCH] rxrpc: Add per-peer RTT tracker Add a function to track the average RTT for a peer. Sources of RTT data will be added in subsequent patches. The RTT data will be useful in the future for determining resend timeouts and for handling the slow-start part of the Rx protocol. Also add a pair of tracepoints, one to log transmissions to elicit a response for RTT purposes and one to log responses that contribute RTT data. Signed-off-by: David Howells --- include/trace/events/rxrpc.h | 61 ++++++++++++++++++++++++++++++++++++ net/rxrpc/ar-internal.h | 25 ++++++++++++--- net/rxrpc/misc.c | 8 +++++ net/rxrpc/peer_event.c | 41 ++++++++++++++++++++++++ 4 files changed, 131 insertions(+), 4 deletions(-) diff --git a/include/trace/events/rxrpc.h b/include/trace/events/rxrpc.h index 75a5d8bf50e1..e8f2afbbe0bf 100644 --- a/include/trace/events/rxrpc.h +++ b/include/trace/events/rxrpc.h @@ -353,6 +353,67 @@ TRACE_EVENT(rxrpc_recvmsg, __entry->ret) ); +TRACE_EVENT(rxrpc_rtt_tx, + TP_PROTO(struct rxrpc_call *call, enum rxrpc_rtt_tx_trace why, + rxrpc_serial_t send_serial), + + TP_ARGS(call, why, send_serial), + + TP_STRUCT__entry( + __field(struct rxrpc_call *, call ) + __field(enum rxrpc_rtt_tx_trace, why ) + __field(rxrpc_serial_t, send_serial ) + ), + + TP_fast_assign( + __entry->call = call; + __entry->why = why; + __entry->send_serial = send_serial; + ), + + TP_printk("c=%p %s sr=%08x", + __entry->call, + rxrpc_rtt_tx_traces[__entry->why], + __entry->send_serial) + ); + +TRACE_EVENT(rxrpc_rtt_rx, + TP_PROTO(struct rxrpc_call *call, enum rxrpc_rtt_rx_trace why, + rxrpc_serial_t send_serial, rxrpc_serial_t resp_serial, + s64 rtt, u8 nr, s64 avg), + + TP_ARGS(call, why, send_serial, resp_serial, rtt, nr, avg), + + TP_STRUCT__entry( + __field(struct rxrpc_call *, call ) + __field(enum rxrpc_rtt_rx_trace, why ) + __field(u8, nr ) + __field(rxrpc_serial_t, send_serial ) + __field(rxrpc_serial_t, resp_serial ) + __field(s64, rtt ) + __field(u64, avg ) + ), + + TP_fast_assign( + __entry->call = call; + __entry->why = why; + __entry->send_serial = send_serial; + __entry->resp_serial = resp_serial; + __entry->rtt = rtt; + __entry->nr = nr; + __entry->avg = avg; + ), + + TP_printk("c=%p %s sr=%08x rr=%08x rtt=%lld nr=%u avg=%lld", + __entry->call, + rxrpc_rtt_rx_traces[__entry->why], + __entry->send_serial, + __entry->resp_serial, + __entry->rtt, + __entry->nr, + __entry->avg) + ); + #endif /* _TRACE_RXRPC_H */ /* This part must be outside protection */ diff --git a/net/rxrpc/ar-internal.h b/net/rxrpc/ar-internal.h index dcf54e3fb478..79c671e552c3 100644 --- a/net/rxrpc/ar-internal.h +++ b/net/rxrpc/ar-internal.h @@ -258,10 +258,11 @@ struct rxrpc_peer { /* calculated RTT cache */ #define RXRPC_RTT_CACHE_SIZE 32 - suseconds_t rtt; /* current RTT estimate (in uS) */ - unsigned int rtt_point; /* next entry at which to insert */ - unsigned int rtt_usage; /* amount of cache actually used */ - suseconds_t rtt_cache[RXRPC_RTT_CACHE_SIZE]; /* calculated RTT cache */ + u64 rtt; /* Current RTT estimate (in nS) */ + u64 rtt_sum; /* Sum of cache contents */ + u64 rtt_cache[RXRPC_RTT_CACHE_SIZE]; /* Determined RTT cache */ + u8 rtt_cursor; /* next entry at which to insert */ + u8 rtt_usage; /* amount of cache actually used */ }; /* @@ -657,6 +658,20 @@ enum rxrpc_recvmsg_trace { extern const char rxrpc_recvmsg_traces[rxrpc_recvmsg__nr_trace][5]; +enum rxrpc_rtt_tx_trace { + rxrpc_rtt_tx_ping, + rxrpc_rtt_tx__nr_trace +}; + +extern const char rxrpc_rtt_tx_traces[rxrpc_rtt_tx__nr_trace][5]; + +enum rxrpc_rtt_rx_trace { + rxrpc_rtt_rx_ping_response, + rxrpc_rtt_rx__nr_trace +}; + +extern const char rxrpc_rtt_rx_traces[rxrpc_rtt_rx__nr_trace][5]; + extern const char *const rxrpc_pkts[]; extern const char *rxrpc_acks(u8 reason); @@ -955,6 +970,8 @@ void rxrpc_reject_packets(struct rxrpc_local *); */ void rxrpc_error_report(struct sock *); void rxrpc_peer_error_distributor(struct work_struct *); +void rxrpc_peer_add_rtt(struct rxrpc_call *, enum rxrpc_rtt_rx_trace, + rxrpc_serial_t, rxrpc_serial_t, ktime_t, ktime_t); /* * peer_object.c diff --git a/net/rxrpc/misc.c b/net/rxrpc/misc.c index 026e1f2e83ff..6321c23f9a6e 100644 --- a/net/rxrpc/misc.c +++ b/net/rxrpc/misc.c @@ -182,3 +182,11 @@ const char rxrpc_recvmsg_traces[rxrpc_recvmsg__nr_trace][5] = { [rxrpc_recvmsg_to_be_accepted] = "TBAC", [rxrpc_recvmsg_return] = "RETN", }; + +const char rxrpc_rtt_tx_traces[rxrpc_rtt_tx__nr_trace][5] = { + [rxrpc_rtt_tx_ping] = "PING", +}; + +const char rxrpc_rtt_rx_traces[rxrpc_rtt_rx__nr_trace][5] = { + [rxrpc_rtt_rx_ping_response] = "PONG", +}; diff --git a/net/rxrpc/peer_event.c b/net/rxrpc/peer_event.c index 18276e7cb9e0..bf13b8470c9a 100644 --- a/net/rxrpc/peer_event.c +++ b/net/rxrpc/peer_event.c @@ -305,3 +305,44 @@ void rxrpc_peer_error_distributor(struct work_struct *work) rxrpc_put_peer(peer); _leave(""); } + +/* + * Add RTT information to cache. This is called in softirq mode and has + * exclusive access to the peer RTT data. + */ +void rxrpc_peer_add_rtt(struct rxrpc_call *call, enum rxrpc_rtt_rx_trace why, + rxrpc_serial_t send_serial, rxrpc_serial_t resp_serial, + ktime_t send_time, ktime_t resp_time) +{ + struct rxrpc_peer *peer = call->peer; + s64 rtt; + u64 sum = peer->rtt_sum, avg; + u8 cursor = peer->rtt_cursor, usage = peer->rtt_usage; + + rtt = ktime_to_ns(ktime_sub(resp_time, send_time)); + if (rtt < 0) + return; + + /* Replace the oldest datum in the RTT buffer */ + sum -= peer->rtt_cache[cursor]; + sum += rtt; + peer->rtt_cache[cursor] = rtt; + peer->rtt_cursor = (cursor + 1) & (RXRPC_RTT_CACHE_SIZE - 1); + peer->rtt_sum = sum; + if (usage < RXRPC_RTT_CACHE_SIZE) { + usage++; + peer->rtt_usage = usage; + } + + /* Now recalculate the average */ + if (usage == RXRPC_RTT_CACHE_SIZE) { + avg = sum / RXRPC_RTT_CACHE_SIZE; + } else { + avg = sum; + do_div(avg, usage); + } + + peer->rtt = avg; + trace_rxrpc_rtt_rx(call, why, send_serial, resp_serial, rtt, + usage, avg); +}