Date: Sun, 01 Jul 2012 19:20:11 +0300 From: Mikolaj Golub <trociny@freebsd.org> To: Mykola Zubach <zuborg@example.com>, freebsd-net@FreeBSD.org Cc: Robert Watson <rwatson@FreeBSD.org>, bug-followup@FreeBSD.org Subject: Re: bin/151937: [patch] netstat(1) utility lack support of displaying rtt related counters of tcp sockets Message-ID: <861ukvpi6c.fsf@kopusha.home.net>
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Hi,
Mykola, thank you for the report and the provided patch. Displaying rtt
related counters per connection looks useful for me too.
I am attaching the modified version of the patch to discuss (and commit if
there are no objections or other suggestions).
The differences from your version:
1) '-T' option is already used. Also, I don't like very much adding yet
another option, so I added the statistics to '-x' option. Or it can be added
to '-T' statistics.
2) As counter names I used names that are close to field names in the tcpcb
structure.
3) To get hz, instead of kern.clockrate, I use kern.hz sysctl (as it
simplifies the code a little) and for !live case read it from the dump.
4) The trick with printing to buf is used to pad the counters on the right, as
it is with other counters.
Also, it might be enough to display only srtt and rttvar statistics?
--
Mikolaj Golub
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Content-Type: text/x-patch
Content-Disposition: attachment; filename=netstat.rtt.2.patch
Index: usr.bin/netstat/inet.c
===================================================================
--- usr.bin/netstat/inet.c (revision 237835)
+++ usr.bin/netstat/inet.c (working copy)
@@ -293,6 +293,28 @@ fail:
#undef KREAD
}
+static const char *
+humanize_rtt(int val, int scale)
+{
+ size_t len;
+ static int hz;
+ static char buf[16];
+
+ if (hz == 0) {
+ hz = 1;
+ if (live) {
+ len = sizeof(hz);
+ if (sysctlbyname("kern.hz", &hz, &len, NULL, 0) == -1)
+ warn("sysctl: kern.hz");
+ } else {
+ kread(hz_addr, &hz, sizeof(hz));
+ }
+ }
+ snprintf(buf, sizeof(buf), "%.3f", (float)val / (scale * hz));
+
+ return (buf);
+}
+
/*
* Print a summary of connections related to an Internet
* protocol. For TCP, also give state of connection.
@@ -441,6 +463,8 @@ protopr(u_long off, const char *name, int af1, int
printf(" %7.7s %7.7s %7.7s %7.7s %7.7s %7.7s",
"rexmt", "persist", "keep",
"2msl", "delack", "rcvtime");
+ printf(" %7.7s %7.7s %7.7s %9.9s",
+ "srtt", "rttvar", "rttlow", "rttupdate");
}
putchar('\n');
first = 0;
@@ -548,6 +572,14 @@ protopr(u_long off, const char *name, int af1, int
timer->tt_2msl / 1000, (timer->tt_2msl % 1000) / 10,
timer->tt_delack / 1000, (timer->tt_delack % 1000) / 10,
timer->t_rcvtime / 1000, (timer->t_rcvtime % 1000) / 10);
+ if (tp != NULL) {
+ printf(" %7s", humanize_rtt(tp->t_srtt,
+ TCP_RTT_SCALE));
+ printf(" %7s", humanize_rtt(tp->t_rttvar,
+ TCP_RTTVAR_SCALE));
+ printf(" %7s", humanize_rtt(tp->t_rttlow, 1));
+ printf(" %9lu ", tp->t_rttupdated);
+ }
}
if (istcp && !Lflag && !xflag && !Tflag) {
if (tp->t_state < 0 || tp->t_state >= TCP_NSTATES)
Index: usr.bin/netstat/main.c
===================================================================
--- usr.bin/netstat/main.c (revision 237835)
+++ usr.bin/netstat/main.c (working copy)
@@ -184,6 +184,8 @@ static struct nlist nl[] = {
{ .n_name = "_arpstat" },
#define N_UNP_SPHEAD 56
{ .n_name = "unp_sphead" },
+#define N_HZ 57
+ { .n_name = "_hz" },
{ .n_name = NULL },
};
@@ -358,6 +360,8 @@ int unit; /* unit number for above */
int af; /* address family */
int live; /* true if we are examining a live system */
+u_long hz_addr; /* address of hz variable in kernel memory */
+
int
main(int argc, char *argv[])
{
@@ -563,6 +567,7 @@ main(int argc, char *argv[])
*/
#endif
kread(0, NULL, 0);
+ hz_addr = nl[N_HZ].n_value;
if (iflag && !sflag) {
intpr(interval, nl[N_IFNET].n_value, NULL);
exit(0);
Index: usr.bin/netstat/netstat.h
===================================================================
--- usr.bin/netstat/netstat.h (revision 237835)
+++ usr.bin/netstat/netstat.h (working copy)
@@ -59,6 +59,8 @@ extern int unit; /* unit number for above */
extern int af; /* address family */
extern int live; /* true if we are examining a live system */
+extern u_long hz_addr; /* address of hz variable in kernel memory */
+
int kread(u_long addr, void *buf, size_t size);
const char *plural(uintmax_t);
const char *plurales(uintmax_t);
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