bin/151937: [patch] netstat(1) utility lack support of displaying rtt related counters of tcp sockets

[Mykola Zubach]

>Number:         151937
>Category:       bin
>Synopsis:       [patch] netstat(1) utility lack support of displaying rtt related counters of tcp sockets
>Confidential:   no
>Severity:       non-critical
>Priority:       low
>Responsible:    freebsd-bugs
>State:          open
>Quarter:        
>Keywords:       
>Date-Required:
>Class:          change-request
>Submitter-Id:   current-users
>Arrival-Date:   Thu Nov 04 14:00:17 UTC 2010
>Closed-Date:
>Last-Modified:
>Originator:     Mykola Zubach
>Release:        FreeBSD 8.1
>Organization:
AdvancedHosters.com
>Environment:
>Description:
RTT (round-trip time) timings are useful to investigate networking issues.
There are a lot of various tools to measure rtt (like ping/mtr etc), but it would be also helpful to have possibility to see current values of rtt for some tcp socket.

Here is a patch for netstat(1) utility which adds four optional columns for tcp sockets:
RTT - smoothed rtt value (tp->t_srtt / hz / TCP_RTT_SCALE)
RTT-DEV - smoothed rtt variance (tp->t_rttvar / hz / TCP_RTTVAR_SCALE)
RTT-LOW - smallest observed rtt (tp->t_rttlow / hz)
RTT-CNT - number of times rtt sampled (tp->t_rttupdated)

First three columns provide timings, measured in seconds, with precision 0.001 s.

'-T' option is free at the moment, so I chose it for this patch since it is related to 'T'imings
>How-To-Repeat:

>Fix:


Patch attached with submission follows:

--- /usr/src/usr.bin/netstat/main.c	2010-06-14 05:09:06.000000000 +0300
+++ main.c	2010-11-03 17:55:49.000000000 +0200
@@ -338,6 +338,7 @@
 static int pflag;	/* show given protocol */
 int	rflag;		/* show routing tables (or routing stats) */
 int	sflag;		/* show protocol statistics */
+int	Tflag;		/* show rtt counters of tcp sockets */
 int	tflag;		/* show i/f watchdog timers */
 int	Wflag;		/* wide display */
 int	xflag;		/* extra information, includes all socket buffer info */
@@ -359,7 +360,7 @@
 
 	af = AF_UNSPEC;
 
-	while ((ch = getopt(argc, argv, "AaBbdf:ghI:iLlM:mN:np:q:rSstuWw:xz")) != -1)
+	while ((ch = getopt(argc, argv, "AaBbdf:ghI:iLlM:mN:np:q:rSsTtuWw:xz")) != -1)
 		switch(ch) {
 		case 'A':
 			Aflag = 1;
@@ -459,6 +460,9 @@
 		case 'S':
 			numeric_addr = 1;
 			break;
+		case 'T':
+			Tflag = 1;
+			break;
 		case 't':
 			tflag = 1;
 			break;
--- /usr/src/usr.bin/netstat/netstat.h	2010-06-14 05:09:06.000000000 +0300
+++ netstat.h	2010-11-03 17:56:08.000000000 +0200
@@ -50,6 +50,7 @@
 extern int	numeric_port;	/* show ports numerically */
 extern int	rflag;	/* show routing tables (or routing stats) */
 extern int	sflag;	/* show protocol statistics */
+extern int	Tflag;	/* show rtt counters of tcp sockets */
 extern int	tflag;	/* show i/f watchdog timers */
 extern int	Wflag;	/* wide display */
 extern int	xflag;	/* extended display, includes all socket buffer info */
--- /usr/src/usr.bin/netstat/inet.c	2010-06-14 05:09:06.000000000 +0300
+++ inet.c	2010-11-04 15:31:45.000000000 +0200
@@ -47,6 +47,7 @@
 #include <sys/socket.h>
 #include <sys/socketvar.h>
 #include <sys/sysctl.h>
+#include <sys/time.h>
 
 #include <net/route.h>
 #include <net/if_arp.h>
@@ -313,6 +314,21 @@
 	struct inpcb *inp;
 	struct xinpgen *xig, *oxig;
 	struct xsocket *so;
+	struct clockinfo clockinfo;
+	int mib[2];
+	size_t ci_size;
+	int hz = 1;
+	float rtt, rtt_var, rtt_low;
+
+	ci_size = sizeof(clockinfo);
+	mib[0] = CTL_KERN;
+	mib[1] = KERN_CLOCKRATE;
+	if (sysctl(mib, 2, &clockinfo, &ci_size, NULL, 0) < 0)
+		warn("sysctl: kern.clockrate");
+	else if (clockinfo.hz == 0)
+		warn("sysctl: kern.clockrate: hz = 0");
+	else
+ 		hz = clockinfo.hz;
 
 	istcp = 0;
 	switch (proto) {
@@ -414,15 +430,17 @@
 				       "%-5.5s %-6.6s %-6.6s  %-22.22s %-22.22s",
 				       "Proto", "Recv-Q", "Send-Q",
 				       "Local Address", "Foreign Address");
+				if (Tflag)
+					printf("%-6.6s %-7.7s %-7.7s %-7.7s ",
+					       	"   RTT", "RTT-VAR",
+						"RTT-LOW", "RTT-CNT");
 				if (xflag)
-					printf("%-6.6s %-6.6s %-6.6s %-6.6s %-6.6s %-6.6s %-6.6s %-6.6s %-6.6s %-6.6s %-6.6s %-6.6s %s\n",
+					printf("%-6.6s %-6.6s %-6.6s %-6.6s %-6.6s %-6.6s %-6.6s %-6.6s %-6.6s %-6.6s %-6.6s %-6.6s ",
 					       	"R-MBUF", "S-MBUF", "R-CLUS", 
 						"S-CLUS", "R-HIWA", "S-HIWA", 
 						"R-LOWA", "S-LOWA", "R-BCNT", 
-						"S-BCNT", "R-BMAX", "S-BMAX",
-					       "(state)");
-				else
-					printf("(state)\n");
+						"S-BCNT", "R-BMAX", "S-BMAX");
+				printf("(state)\n");
 			}
 			first = 0;
 		}
@@ -506,6 +524,14 @@
 			} /* else nothing printed now */
 #endif /* INET6 */
 		}
+		if (istcp && Tflag && !Lflag) {
+			rtt = (float)tp->t_srtt / hz / TCP_RTT_SCALE;
+			rtt_var = (float)tp->t_rttvar / hz / TCP_RTTVAR_SCALE;
+			rtt_low = (float)tp->t_rttlow / hz;
+			printf("%6.3f %7.3f %7.3f %7lu ",
+				rtt, rtt_var, rtt_low,
+				tp->t_rttupdated);
+		}
 		if (xflag) {
 			if (Lflag)
 				printf("%21s %6u %6u %6u %6u %6u %6u %6u %6u %6u %6u %6u %6u ",


>Release-Note:
>Audit-Trail:
>Unformatted: