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

Details

Issue Type:Bug
Priority:4 - Normal
Status:Resolved
Created at:2019-08-09T21:33:57.824Z
Updated at:2019-08-22T18:46:05.171Z

People

Created by:Former user
Reported by:Former user
Assigned to:Former user

Resolution

Fixed: A fix for this issue is checked into the tree and tested.
(Resolution Date: 2019-08-22T18:46:05.155Z)

Fix Versions

2019-08-29 Zoo York (Release Date: 2019-08-29)

Description

In TCP, the variance of the RTT is an important value when calculating the RTO. It would be nice if connstat(1M) could print the value so that its change over time could be observed while debugging.

Comments

Comment by Former user
Created at 2019-08-12T20:50:56.756Z
Updated at 2019-08-12T20:52:09.447Z

Using ipdadm to delay packets and lengthen the RTT, I then ran iperf and watched the connection:

[root@test1 ~]# connstat -o laddr,lport,raddr,rport,rto,rtt,rttvar -i 1 -F rport=11845,state=established
LADDR                     LPORT RADDR                     RPORT RTO     RTT     RTTVAR
10.88.88.52               37395 37.153.108.173            11845 15832   4084490 2936976
10.88.88.52               61370 37.153.108.173            11845 11731   5257847 1618366
LADDR                     LPORT RADDR                     RPORT RTO     RTT     RTTVAR
10.88.88.52               37395 37.153.108.173            11845 15832   4084490 2936976
10.88.88.52               61370 37.153.108.173            11845 13271   2245849 2756350
LADDR                     LPORT RADDR                     RPORT RTO     RTT     RTTVAR
10.88.88.52               37395 37.153.108.173            11845 15832   4084490 2936976
10.88.88.52               61370 37.153.108.173            11845 3877    1111031 691737
LADDR                     LPORT RADDR                     RPORT RTO     RTT     RTTVAR
10.88.88.52               37395 37.153.108.173            11845 15832   4084490 2936976
10.88.88.52               61370 37.153.108.173            11845 1962    1180397 195481
LADDR                     LPORT RADDR                     RPORT RTO     RTT     RTTVAR
10.88.88.52               37395 37.153.108.173            11845 15832   4084490 2936976
10.88.88.52               61370 37.153.108.173            11845 2881    1567102 328601
LADDR                     LPORT RADDR                     RPORT RTO     RTT     RTTVAR
10.88.88.52               37395 37.153.108.173            11845 15832   4084490 2936976
10.88.88.52               61370 37.153.108.173            11845 3545    2034765 377762
LADDR                     LPORT RADDR                     RPORT RTO     RTT     RTTVAR
10.88.88.52               37395 37.153.108.173            11845 15832   4084490 2936976
10.88.88.52               61370 37.153.108.173            11845 4076    2514066 390656
LADDR                     LPORT RADDR                     RPORT RTO     RTT     RTTVAR
10.88.88.52               37395 37.153.108.173            11845 15832   4084490 2936976
10.88.88.52               61370 37.153.108.173            11845 4608    3008597 400043
LADDR                     LPORT RADDR                     RPORT RTO     RTT     RTTVAR
10.88.88.52               37395 37.153.108.173            11845 15832   4084490 2936976
10.88.88.52               61370 37.153.108.173            11845 5118    3507171 402813
LADDR                     LPORT RADDR                     RPORT RTO     RTT     RTTVAR
10.88.88.52               37395 37.153.108.173            11845 15832   4084490 2936976
10.88.88.52               61370 37.153.108.173            11845 5622    4006925 403817
LADDR                     LPORT RADDR                     RPORT RTO     RTT     RTTVAR
10.88.88.52               37395 37.153.108.173            11845 15832   4084490 2936976
10.88.88.52               61370 37.153.108.173            11845 6175    4515766 414890
LADDR                     LPORT RADDR                     RPORT RTO     RTT     RTTVAR
10.88.88.52               37395 37.153.108.173            11845 15832   4084490 2936976
10.88.88.52               61370 37.153.108.173            11845 6662    5024585 409439
LADDR                     LPORT RADDR                     RPORT RTO     RTT     RTTVAR
10.88.88.52               37395 37.153.108.173            11845 15832   4084490 2936976
10.88.88.52               61370 37.153.108.173            11845 7149    5526966 405514
LADDR                     LPORT RADDR                     RPORT RTO     RTT     RTTVAR
10.88.88.52               37395 37.153.108.173            11845 15832   4084490 2936976
10.88.88.52               61370 37.153.108.173            11845 7646    6028188 404520
LADDR                     LPORT RADDR                     RPORT RTO     RTT     RTTVAR
10.88.88.52               37395 37.153.108.173            11845 15832   4084490 2936976
10.88.88.52               61370 37.153.108.173            11845 8144    6528537 404033
LADDR                     LPORT RADDR                     RPORT RTO     RTT     RTTVAR
10.88.88.52               37395 37.153.108.173            11845 15832   4084490 2936976
10.88.88.52               61370 37.153.108.173            11845 8644    7028667 403947
LADDR                     LPORT RADDR                     RPORT RTO     RTT     RTTVAR
10.88.88.52               37395 37.153.108.173            11845 15832   4084490 2936976
10.88.88.52               61370 37.153.108.173            11845 9143    7528647 403814
LADDR                     LPORT RADDR                     RPORT RTO     RTT     RTTVAR
10.88.88.52               37395 37.153.108.173            11845 15832   4084490 2936976
10.88.88.52               61370 37.153.108.173            11845 9643    8028627 403766
LADDR                     LPORT RADDR                     RPORT RTO     RTT     RTTVAR
10.88.88.52               37395 37.153.108.173            11845 15832   4084490 2936976
10.88.88.52               61370 37.153.108.173            11845 10143   8528521 403703
LADDR                     LPORT RADDR                     RPORT RTO     RTT     RTTVAR
10.88.88.52               37395 37.153.108.173            11845 15832   4084490 2936976
10.88.88.52               61370 37.153.108.173            11845 10644   9028671 403918
LADDR                     LPORT RADDR                     RPORT RTO     RTT     RTTVAR
10.88.88.52               37395 37.153.108.173            11845 15832   4084490 2936976
10.88.88.52               61370 37.153.108.173            11845 11144   9528654 403838
LADDR                     LPORT RADDR                     RPORT RTO     RTT     RTTVAR
10.88.88.52               37395 37.153.108.173            11845 15832   4084490 2936976
10.88.88.52               61370 37.153.108.173            11845 11643   10028628 403764
LADDR                     LPORT RADDR                     RPORT RTO     RTT     RTTVAR
10.88.88.52               37395 37.153.108.173            11845 15832   4084490 2936976
10.88.88.52               61370 37.153.108.173            11845 12143   10528671 403782
LADDR                     LPORT RADDR                     RPORT RTO     RTT     RTTVAR
10.88.88.52               37395 37.153.108.173            11845 15832   4084490 2936976
10.88.88.52               61370 37.153.108.173            11845 12644   11028711 403843
LADDR                     LPORT RADDR                     RPORT RTO     RTT     RTTVAR
10.88.88.52               37395 37.153.108.173            11845 15832   4084490 2936976
10.88.88.52               61370 37.153.108.173            11845 13141   11528372 403314
LADDR                     LPORT RADDR                     RPORT RTO     RTT     RTTVAR
10.88.88.52               37395 37.153.108.173            11845 15832   4084490 2936976
10.88.88.52               61370 37.153.108.173            11845 13641   12027816 403519
LADDR                     LPORT RADDR                     RPORT RTO     RTT     RTTVAR
10.88.88.52               37395 37.153.108.173            11845 15832   4084490 2936976
10.88.88.52               61370 37.153.108.173            11845 14142   12527683 403654
LADDR                     LPORT RADDR                     RPORT RTO     RTT     RTTVAR
10.88.88.52               37395 37.153.108.173            11845 15832   4084490 2936976
10.88.88.52               61370 37.153.108.173            11845 14643   13027753 403893
LADDR                     LPORT RADDR                     RPORT RTO     RTT     RTTVAR
10.88.88.52               37395 37.153.108.173            11845 15832   4084490 2936976
10.88.88.52               61370 37.153.108.173            11845 15142   13527638 403703
LADDR                     LPORT RADDR                     RPORT RTO     RTT     RTTVAR
10.88.88.52               37395 37.153.108.173            11845 15832   4084490 2936976
10.88.88.52               61370 37.153.108.173            11845 15642   14027596 403828
LADDR                     LPORT RADDR                     RPORT RTO     RTT     RTTVAR
10.88.88.52               37395 37.153.108.173            11845 15832   4084490 2936976
10.88.88.52               61370 37.153.108.173            11845 16143   14527681 403908
LADDR                     LPORT RADDR                     RPORT RTO     RTT     RTTVAR
10.88.88.52               37395 37.153.108.173            11845 15832   4084490 2936976
10.88.88.52               61370 37.153.108.173            11845 16642   15027547 403687
LADDR                     LPORT RADDR                     RPORT RTO     RTT     RTTVAR
10.88.88.52               37395 37.153.108.173            11845 15832   4084490 2936976
10.88.88.52               61370 37.153.108.173            11845 17142   15527589 403803
LADDR                     LPORT RADDR                     RPORT RTO     RTT     RTTVAR
10.88.88.52               37395 37.153.108.173            11845 15832   4084490 2936976
10.88.88.52               61370 37.153.108.173            11845 17643   16027698 403873
LADDR                     LPORT RADDR                     RPORT RTO     RTT     RTTVAR
10.88.88.52               37395 37.153.108.173            11845 15832   4084490 2936976
10.88.88.52               61370 37.153.108.173            11845 18142   16527732 403742
LADDR                     LPORT RADDR                     RPORT RTO     RTT     RTTVAR
10.88.88.52               37395 37.153.108.173            11845 15832   4084490 2936976
10.88.88.52               61370 37.153.108.173            11845 18642   17027637 403822
LADDR                     LPORT RADDR                     RPORT RTO     RTT     RTTVAR
10.88.88.52               37395 37.153.108.173            11845 15832   4084490 2936976
10.88.88.52               61370 37.153.108.173            11845 19142   17527655 403609

Without the ipdadm delay, there's very little variation in the RTT, and we end up getting a quarter of TCP_SD_MIN, which restricts the minimum value for RTTVAR:

[root@test1 ~]# connstat -o laddr,lport,raddr,rport,rto,rtt,rttvar -i 1 -F rport=11845,state=established
LADDR                     LPORT RADDR                     RPORT RTO     RTT     RTTVAR
LADDR                     LPORT RADDR                     RPORT RTO     RTT     RTTVAR
LADDR                     LPORT RADDR                     RPORT RTO     RTT     RTTVAR
10.88.88.52               51259 37.153.108.173            11845 23079   10461404 3154441
LADDR                     LPORT RADDR                     RPORT RTO     RTT     RTTVAR
10.88.88.52               51259 37.153.108.173            11845 31822   8057306 5941408
10.88.88.52               60797 37.153.108.173            11845 23084   10460621 3156007
LADDR                     LPORT RADDR                     RPORT RTO     RTT     RTTVAR
10.88.88.52               51259 37.153.108.173            11845 31822   8057306 5941408
10.88.88.52               60797 37.153.108.173            11845 627     227913  100000
LADDR                     LPORT RADDR                     RPORT RTO     RTT     RTTVAR
10.88.88.52               51259 37.153.108.173            11845 31822   8057306 5941408
10.88.88.52               60797 37.153.108.173            11845 660     260368  100000
LADDR                     LPORT RADDR                     RPORT RTO     RTT     RTTVAR
10.88.88.52               51259 37.153.108.173            11845 31822   8057306 5941408
10.88.88.52               60797 37.153.108.173            11845 660     260368  100000
LADDR                     LPORT RADDR                     RPORT RTO     RTT     RTTVAR
10.88.88.52               51259 37.153.108.173            11845 31822   8057306 5941408
10.88.88.52               60797 37.153.108.173            11845 660     260368  100000
LADDR                     LPORT RADDR                     RPORT RTO     RTT     RTTVAR
10.88.88.52               51259 37.153.108.173            11845 31822   8057306 5941408
10.88.88.52               60797 37.153.108.173            11845 660     260368  100000
LADDR                     LPORT RADDR                     RPORT RTO     RTT     RTTVAR
10.88.88.52               51259 37.153.108.173            11845 31822   8057306 5941408
10.88.88.52               60797 37.153.108.173            11845 660     260368  100000
LADDR                     LPORT RADDR                     RPORT RTO     RTT     RTTVAR
10.88.88.52               51259 37.153.108.173            11845 31822   8057306 5941408
10.88.88.52               60797 37.153.108.173            11845 660     260368  100000
LADDR                     LPORT RADDR                     RPORT RTO     RTT     RTTVAR
10.88.88.52               51259 37.153.108.173            11845 31822   8057306 5941408
10.88.88.52               60797 37.153.108.173            11845 660     260368  100000
LADDR                     LPORT RADDR                     RPORT RTO     RTT     RTTVAR
10.88.88.52               51259 37.153.108.173            11845 31822   8057306 5941408
10.88.88.52               60797 37.153.108.173            11845 660     260368  100000

Comment by Jira Bot
Created at 2019-08-22T18:42:44.799Z

illumos-joyent commit bc729a97a9286d8629f774f23f1edeb945c6b29c (branch master, by Cody Peter Mello)

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>