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authorDavid Howells <dhowells@redhat.com>2016-09-22 00:41:53 +0100
committerDavid Howells <dhowells@redhat.com>2016-09-22 01:26:25 +0100
commitcf1a6474f80735ff4a5d99f3dd68a94dbec8455f (patch)
tree8ca17608fce76f66375297f2395b0943d8f1e988 /net/rxrpc
parentf07373ead455a396e15a431bc08d8ce1dac6f1cf (diff)
download96b-common-cf1a6474f80735ff4a5d99f3dd68a94dbec8455f.tar.gz
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 <dhowells@redhat.com>
Diffstat (limited to 'net/rxrpc')
-rw-r--r--net/rxrpc/ar-internal.h25
-rw-r--r--net/rxrpc/misc.c8
-rw-r--r--net/rxrpc/peer_event.c41
3 files changed, 70 insertions, 4 deletions
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);
+}