OS-7944 Want support for printing RTT variance with connstat(1M)

Reviewed by: Robert Mustacchi <rm@joyent.com>
Approved by: John Levon <john.levon@joyent.com>

4 files changed, 20 insertions, 2 deletions

diff --git a/usr/src/cmd/connstat/connstat_tcp.c b/usr/src/cmd/connstat/connstat_tcp.c
index 4cd20c9b09..bcf2c2ef5b 100644
--- a/usr/src/cmd/connstat/connstat_tcp.c
+++ b/usr/src/cmd/connstat/connstat_tcp.c
@@ -14,6 +14,7 @@
  */
 /*
  * Copyright (c) 2015, 2016 by Delphix. All rights reserved.
+ * Copyright 2019 Joyent, Inc.
  */
 
 #include <stdio.h>
@@ -77,6 +78,7 @@ typedef struct tcp_fields_buf_s {
 	uint64_t t_rtt_sum;
 	int t_state;
 	uint64_t t_rtt;
+	uint64_t t_rttvar;
 } tcp_fields_buf_t;
 
 static boolean_t print_tcp_state(ofmt_arg_t *, char *, uint_t);
@@ -126,6 +128,8 @@ static ofmt_field_t tcp_fields[] = {
 		offsetof(tcp_fields_buf_t, t_rtt_sum),	print_uint64 },
 	{ "RTTC",	11,
 		offsetof(tcp_fields_buf_t, t_rtt_cnt),	print_uint32 },
+	{ "RTTVAR",	8,
+		offsetof(tcp_fields_buf_t, t_rttvar),	print_uint64 },
 	{ "STATE",	12,
 		offsetof(tcp_fields_buf_t, t_state),	print_tcp_state },
 	{ NULL, 0, 0, NULL}
@@ -189,6 +193,7 @@ tcp_ci2buf(struct tcpConnEntryInfo_s *ci)
 	fields_buf.t_rtt = (ci->ce_out_data_segs == 0 ? 0 : ci->ce_rtt_sa);
 	fields_buf.t_rtt_sum = ci->ce_rtt_sum;
 	fields_buf.t_rtt_cnt = ci->ce_rtt_cnt;
+	fields_buf.t_rttvar = ci->ce_rtt_sd;
 	fields_buf.t_state = ci->ce_state;
 }
 
diff --git a/usr/src/man/man1m/connstat.1m b/usr/src/man/man1m/connstat.1m
index 2175fefdb3..e87edbe3eb 100644
--- a/usr/src/man/man1m/connstat.1m
+++ b/usr/src/man/man1m/connstat.1m
@@ -14,8 +14,9 @@
 .\"
 .\"
 .\" Copyright (c) 2016 by Delphix. All rights reserved.
+.\" Copyright 2019 Joyent, Inc.
 .\"
-.Dd July 5, 2016
+.Dd August 15, 2019
 .Dt CONNSTAT 1M
 .Os
 .Sh NAME
@@ -165,6 +166,9 @@ The current retransmission timeout in milliseconds.
 .It Sy rtt
 The current smoothed round-trip time to the peer in microseconds.
 The smoothed RTT average algorithm used is as described in RFC 6298.
+.It Sy rttvar
+The current smoothed variation of the round-trip time to the peer in
+microseconds.
 .It Sy rttc
 The number of times that a round-trip sample was added to
 .Sy rtts .
diff --git a/usr/src/uts/common/inet/mib2.h b/usr/src/uts/common/inet/mib2.h
index 847ad1c560..9a9d4e15d3 100644
--- a/usr/src/uts/common/inet/mib2.h
+++ b/usr/src/uts/common/inet/mib2.h
@@ -23,6 +23,7 @@
 /*
  * Copyright (c) 1990 Mentat Inc.
  * Copyright (c) 2015, 2016 by Delphix. All rights reserved.
+ * Copyright 2019 Joyent, Inc.
  */
 
 #ifndef	_INET_MIB2_H
@@ -1388,6 +1389,8 @@ typedef struct mib2_tcpConnEntry {
 		Gauge		ce_rwnd;
 				/* round-trip time smoothed average (us) */
 		Gauge		ce_rtt_sa;
+				/* round-trip time smoothed deviation (us) */
+		Gauge		ce_rtt_sd;
 				/* current rto (retransmit timeout) */
 		Gauge		ce_rto;
 				/* round-trip time count */
diff --git a/usr/src/uts/common/inet/tcp/tcp_stats.c b/usr/src/uts/common/inet/tcp/tcp_stats.c
index dbf320d09d..0da7f5413c 100644
--- a/usr/src/uts/common/inet/tcp/tcp_stats.c
+++ b/usr/src/uts/common/inet/tcp/tcp_stats.c
@@ -23,6 +23,7 @@
  * Copyright (c) 2010, Oracle and/or its affiliates. All rights reserved.
  * Copyright (c) 2011, Joyent Inc. All rights reserved.
  * Copyright (c) 2015, 2016 by Delphix. All rights reserved.
+ * Copyright 2019 Joyent, Inc.
  */
 
 #include <sys/types.h>
@@ -126,9 +127,14 @@ tcp_set_conninfo(tcp_t *tcp, struct tcpConnEntryInfo_s *tcei, boolean_t ispriv)
 	tcei->ce_rto =  tcp->tcp_rto;
 	tcei->ce_mss =  tcp->tcp_mss;
 	tcei->ce_state = tcp->tcp_state;
-	tcei->ce_rtt_sa = NSEC2USEC(tcp->tcp_rtt_sa >> 3);
 	tcei->ce_rtt_sum = NSEC2USEC(tcp->tcp_rtt_sum);
 	tcei->ce_rtt_cnt = tcp->tcp_rtt_cnt;
+
+	/* tcp_rtt_sa is stored as 8 times the average RTT */
+	tcei->ce_rtt_sa = NSEC2USEC(tcp->tcp_rtt_sa >> 3);
+
+	/* tcp_rtt_sd is stored as 4 times the average RTTVAR */
+	tcei->ce_rtt_sd = NSEC2USEC(tcp->tcp_rtt_sd >> 2);
 }
 
 /*