Roundtrip mode
==============

This pair of tools can be used also to measure roundtrip
latency/throughput in addition to the default mode (where
there are no replies) by using '-r' switch with the dping.

For example:

dpong 10000 &
dping -r 10000

(if the amount of messages is not given, the default value of 1000
will be used)

Currently the roundtrip latency seems to be a bit more than 2x the
single-way (no replies) latency, with the reply taking more time than
the original message.

As an example, Fremantle, w46 release (with syslog), on N900:

single-way (fire-and-forget):

Timestamp: 1400652543 microseconds
MESSAGES recv 1000 lost 0 LATENCY min 113952 avg 191407 max 262817 THROUGHPUT 1296.6 m/s
Timestamp: 1401427446 microseconds
MESSAGES recv 1000 lost 0 LATENCY min 116333 avg 186109 max 260620 THROUGHPUT 1290.7 m/s

Roundtrip mode:

Timestamp: 1476999864 microseconds
Dping->dpong statistics: LATENCY min 143463 avg 181594 max 222106
dping<-dpong statistics: LATENCY min 264466 avg 298409 max 326050
Statistics for the whole roundtrip:
MESSAGES recv 1000 lost 0 LATENCY min 407929 avg 480003 max 548156 THROUGHPUT 585.2 m/s

Timestamp: 1478743455 microseconds
Dping->dpong statistics: LATENCY min 148620 avg 181843 max 224335
dping<-dpong statistics: LATENCY min 267578 avg 297071 max 328705
Statistics for the whole roundtrip:
MESSAGES recv 1000 lost 0 LATENCY min 416198 avg 478914 max 553040 THROUGHPUT 573.6 m/s


Comments on old test results from Nokia 770:
============================================

When using the following test pattern (server and client):
   run-standalone.sh ./dpong
   run-standalone.sh ./dping

The build w40 test results:

When there's enough free memory and system is idle:
   MESSAGES recv 100 lost 0 LATENCY min 1525 avg 1564 max 2014
   MESSAGES recv 100 lost 0 LATENCY min 1525 avg 1555 max 1770
   MESSAGES recv 100 lost 0 LATENCY min 1525 avg 1562 max 1861
   MESSAGES recv 100 lost 0 LATENCY min 1525 avg 1566 max 1830
   MESSAGES recv 100 lost 0 LATENCY min 1525 avg 1563 max 1861
   MESSAGES recv 100 lost 0 LATENCY min 1525 avg 1562 max 1801
   MESSAGES recv 100 lost 0 LATENCY min 1525 avg 1560 max 1862
   MESSAGES recv 100 lost 0 LATENCY min 1525 avg 1561 max 1831
   MESSAGES recv 100 lost 0 LATENCY min 1525 avg 1563 max 1800

= 1.6 ms average and 1.8 ms maximum message latency.

When Browser is started:
   MESSAGES recv 100 lost 0 LATENCY min 1525 avg 2314 max 67018
   MESSAGES recv 100 lost 0 LATENCY min 1525 avg 8702 max 686065
   MESSAGES recv 100 lost 0 LATENCY min 1525 avg 6736 max 410125
   MESSAGES recv 100 lost 0 LATENCY min 1525 avg 13454 max 1151489
   MESSAGES recv 100 lost 0 LATENCY min 1586 avg 16958 max 668946
   MESSAGES recv 100 lost 0 LATENCY min 2564 avg 15920 max 257050

= 16 ms average and up to 1151 ms maximum message latency.

Restarting dpong so that it reports at 1000 messages intervals because
100 messages interval is too short:

   Nokia770-41:~# run-standalone.sh ./dpong 1000
   ping server
   reporting period is set to 1000 messages
   ping server is ready to accept calls
   MESSAGES recv 931 lost 64068 LATENCY min 1586 avg 1736 max 20722
   MESSAGES recv 1000 lost 0 LATENCY min 1586 avg 1688 max 44403
   MESSAGES recv 1000 lost 0 LATENCY min 1586 avg 1629 max 3509
   MESSAGES recv 1000 lost 0 LATENCY min 1586 avg 2385 max 161102
   MESSAGES recv 1000 lost 0 LATENCY min 1586 avg 4758 max 46326
   MESSAGES recv 1000 lost 0 LATENCY min 1586 avg 1634 max 3480
   MESSAGES recv 1000 lost 0 LATENCY min 1586 avg 2684 max 87311
   MESSAGES recv 1000 lost 0 LATENCY min 1586 avg 1634 max 4272
   MESSAGES recv 1000 lost 0 LATENCY min 1586 avg 2367 max 131012

Now, with high memory consumption, attempting Browser switch:
   MESSAGES recv 1000 lost 0 LATENCY min 4608 avg 19670 max 478089
   MESSAGES recv 1000 lost 0 LATENCY min 2899 avg 19219 max 332123
   MESSAGES recv 1000 lost 0 LATENCY min 4548 avg 22953 max 728118
   MESSAGES recv 1000 lost 0 LATENCY min 1586 avg 1890 max 39947
   MESSAGES recv 1000 lost 0 LATENCY min 1586 avg 1723 max 44342
   MESSAGES recv 1000 lost 0 LATENCY min 1586 avg 1736 max 14130
   MESSAGES recv 1000 lost 0 LATENCY min 1586 avg 1690 max 3449
   MESSAGES recv 1000 lost 0 LATENCY min 1586 avg 1723 max 44373
   MESSAGES recv 1000 lost 0 LATENCY min 1586 avg 7859 max 329132

= 8.7 ms average and up to 72 ms maximum message latency.

High memory usage, idle device:
   MESSAGES recv 1000 lost 0 LATENCY min 1586 avg 4959 max 146392
   MESSAGES recv 1000 lost 0 LATENCY min 1556 avg 3083 max 186768
   MESSAGES recv 1000 lost 0 LATENCY min 1556 avg 1633 max 3601
   MESSAGES recv 1000 lost 0 LATENCY min 1586 avg 1676 max 45013
   MESSAGES recv 1000 lost 0 LATENCY min 1586 avg 1632 max 3601
   MESSAGES recv 1000 lost 0 LATENCY min 1556 avg 1629 max 3417
   MESSAGES recv 1000 lost 0 LATENCY min 1586 avg 1630 max 3387
   MESSAGES recv 1000 lost 0 LATENCY min 1586 avg 1632 max 3632
   MESSAGES recv 1000 lost 0 LATENCY min 1586 avg 1682 max 14343
   MESSAGES recv 1000 lost 0 LATENCY min 1586 avg 1629 max 3570
   MESSAGES recv 1000 lost 0 LATENCY min 1586 avg 1635 max 3449
   MESSAGES recv 1000 lost 0 LATENCY min 1586 avg 1631 max 2990

= Average latency higher than usual, but maximum is inconsistent
  and taking up to 45 ms.

After closing dpong server (just running dping), this (pre-)release
gets rebooted in about 1 minute.



Experiments with priorities:
   Use case
   run-standalone.sh dpong &
   run-standalone.sh dping & ls -R / > /dev/null

   original session server:
      MESSAGES recv 100 lost 0 LATENCY min 1556 avg 2491 max 79834
      MESSAGES recv 100 lost 0 LATENCY min 1556 avg 1656 max 6133
      MESSAGES recv 100 lost 0 LATENCY min 1556 avg 2462 max 79926
      MESSAGES recv 100 lost 0 LATENCY min 1556 avg 1653 max 6257
      MESSAGES recv 100 lost 0 LATENCY min 1556 avg 1650 max 6287
      MESSAGES recv 100 lost 0 LATENCY min 1556 avg 1650 max 6317
      MESSAGES recv 100 lost 0 LATENCY min 1556 avg 1656 max 6286
      MESSAGES recv 100 lost 0 LATENCY min 1556 avg 1739 max 6286
      MESSAGES recv 100 lost 0 LATENCY min 1556 avg 1647 max 6226
      MESSAGES recv 100 lost 0 LATENCY min 1556 avg 1648 max 6257
      MESSAGES recv 100 lost 0 LATENCY min 1556 avg 3858 max 220398
      MESSAGES recv 100 lost 0 LATENCY min 1556 avg 2261 max 59356
      MESSAGES recv 100 lost 0 LATENCY min 1556 avg 2480 max 79803
      MESSAGES recv 100 lost 0 LATENCY min 1556 avg 1598 max 1954
      MESSAGES recv 100 lost 0 LATENCY min 1556 avg 2427 max 79865
      MESSAGES recv 100 lost 0 LATENCY min 1556 avg 1684 max 6164
      MESSAGES recv 100 lost 0 LATENCY min 1556 avg 1599 max 1770
      MESSAGES recv 100 lost 0 LATENCY min 1556 avg 1643 max 6134
      MESSAGES recv 100 lost 0 LATENCY min 1556 avg 2344 max 13031
      MESSAGES recv 100 lost 0 LATENCY min 1556 avg 9528 max 711976
      MESSAGES recv 100 lost 0 LATENCY min 1556 avg 2573 max 52551
      MESSAGES recv 100 lost 0 LATENCY min 2350 avg 5217 max 266877
      MESSAGES recv 100 lost 0 LATENCY min 2349 avg 2674 max 7781

= Maximum registered latency is 712 ms
  -> problems in message routing & consumption

nice -10 dbus session server:
      MESSAGES recv 100 lost 0 LATENCY min 2197 avg 10088 max 757661
      MESSAGES recv 100 lost 0 LATENCY min 2227 avg 2463 max 6928
      MESSAGES recv 100 lost 0 LATENCY min 2228 avg 2433 max 6470
      MESSAGES recv 100 lost 0 LATENCY min 2228 avg 2921 max 50416
      MESSAGES recv 100 lost 0 LATENCY min 2227 avg 2418 max 7171
      MESSAGES recv 100 lost 0 LATENCY min 2228 avg 2507 max 7141
      MESSAGES recv 100 lost 0 LATENCY min 2227 avg 2403 max 6989
      MESSAGES recv 100 lost 0 LATENCY min 2228 avg 2418 max 7141
      MESSAGES recv 100 lost 0 LATENCY min 2228 avg 2841 max 28900
      MESSAGES recv 100 lost 0 LATENCY min 2228 avg 2601 max 6989
      MESSAGES recv 100 lost 0 LATENCY min 2228 avg 2506 max 7722
      MESSAGES recv 100 lost 0 LATENCY min 2228 avg 2449 max 6988
      MESSAGES recv 100 lost 0 LATENCY min 2227 avg 2600 max 17976
      MESSAGES recv 100 lost 0 LATENCY min 2227 avg 2773 max 31555
      MESSAGES recv 100 lost 0 LATENCY min 2227 avg 2570 max 12085
      MESSAGES recv 100 lost 0 LATENCY min 2228 avg 2472 max 6989
      MESSAGES recv 100 lost 0 LATENCY min 2228 avg 2397 max 6745
      MESSAGES recv 100 lost 0 LATENCY min 2227 avg 2904 max 45013
      MESSAGES recv 100 lost 0 LATENCY min 2227 avg 2574 max 6745
      MESSAGES recv 100 lost 0 LATENCY min 2228 avg 2678 max 6927
      MESSAGES recv 100 lost 0 LATENCY min 2228 avg 3117 max 12756

= Maximum registered latency is 758 ms
  -> problem in message consumption

nice -10 dbus session server + nice -10 for dpong:
      MESSAGES recv 100 lost 0 LATENCY min 1191 avg 1332 max 1495
      MESSAGES recv 100 lost 0 LATENCY min 1191 avg 1335 max 1526
      MESSAGES recv 100 lost 0 LATENCY min 1252 avg 1378 max 4791
      MESSAGES recv 100 lost 0 LATENCY min 1312 avg 1349 max 1983
      MESSAGES recv 100 lost 0 LATENCY min 1252 avg 1335 max 1526
      MESSAGES recv 100 lost 0 LATENCY min 1251 avg 1338 max 1708
      MESSAGES recv 100 lost 0 LATENCY min 1251 avg 1340 max 1891
      MESSAGES recv 100 lost 0 LATENCY min 1251 avg 1339 max 1678
      MESSAGES recv 100 lost 0 LATENCY min 1220 avg 1377 max 4883
      MESSAGES recv 100 lost 0 LATENCY min 1220 avg 1334 max 1801
      MESSAGES recv 100 lost 0 LATENCY min 1251 avg 1334 max 1496
      MESSAGES recv 100 lost 0 LATENCY min 1312 avg 1337 max 1953
      MESSAGES recv 100 lost 0 LATENCY min 1251 avg 1330 max 1527
      MESSAGES recv 100 lost 0 LATENCY min 1312 avg 3037 max 16632
      MESSAGES recv 100 lost 0 LATENCY min 2075 avg 2374 max 3785
      MESSAGES recv 100 lost 0 LATENCY min 1191 avg 2115 max 79803
      MESSAGES recv 100 lost 0 LATENCY min 1251 avg 2160 max 79711
      MESSAGES recv 100 lost 0 LATENCY min 1220 avg 1349 max 2289
      MESSAGES recv 100 lost 0 LATENCY min 1281 avg 2214 max 45593
      MESSAGES recv 100 lost 0 LATENCY min 1221 avg 1335 max 1770
      MESSAGES recv 100 lost 0 LATENCY min 1190 avg 1352 max 2747
      MESSAGES recv 100 lost 0 LATENCY min 1220 avg 1364 max 4761
      MESSAGES recv 100 lost 0 LATENCY min 1190 avg 1347 max 2319
      MESSAGES recv 100 lost 0 LATENCY min 1252 avg 1337 max 1740

= Maximum registered latency is 80 ms
  -> situation looks much better!

"top" report from last experiment:
      Mem: 60324K used, 1512K free, 0K shrd, 240K buff, 21684K cached
      Load average: 2.24, 1.48, 0.74    (State: S=sleeping R=running, W=waiting)

      PID USER     STATUS   RSS  PPID %CPU %MEM COMMAND
      761 user     S <     1012   268 44.7  1.6 dbus-daemon-1
      775 root     S <      940   770 29.9  1.5 dpong
      782 root     R        800   776 22.0  1.2 dping
      805 root     R        752   803  1.5  1.2 top
      801 root     S       1772   459  0.9  2.8 sshd
      275 root     S        364   268  0.7  0.5 bme
      680 user     S <     8116   268  0.0 13.1 maemo_af_deskto
      691 user     S       6936   268  0.0 11.2 hildon-input-me
      620 systemui S <     5472   268  0.0  8.8 systemui
      644 user     S <     5120     1  0.0  8.2 maemo-launcher
      762 user     S <     4736   268  0.0  7.6 osso-media-serv
      684 user     S <     4096   268  0.0  6.6 osso-connectivi
      462 root     S <     2904   268  0.0  4.6 Xomap
      506 user     S <     2668   268  0.0  4.3 sapwood-server
      764 user     S       2208     1  0.0  3.5 dbus-vfs-daemon
      765 user     S       2208   764  0.0  3.5 dbus-vfs-daemon
      766 user     S       2208   765  0.0  3.5 dbus-vfs-daemon
      510 user     S <     2136   268  0.0  3.4 matchbox-window
      741 root     S       1740     1  0.0  2.8 osso_alarm
      599 messageb S <     1448   268  0.0  2.3 gconfd-2
      451 messageb S <     1420   268  0.0  2.2 dbus-daemon-1
      624 root     S <     1412   268  0.0  2.2 btcond
      591 root     S <     1360   268  0.0  2.1 mce

Processes status after last experiment:
   Nokia770-41:~# cat /proc/761/status
      Name:   dbus-daemon-1
      State:  S (sleeping)
      SleepAVG:       98%
      Tgid:   761
      Pid:    761
      PPid:   268
      TracerPid:      0
      Uid:    29999   29999   29999   29999
      Gid:    29999   29999   29999   29999
      FDSize: 32
      Groups: 20 29999
      VmSize:     2100 kB
      VmLck:         0 kB
      VmRSS:      1012 kB
      VmData:      156 kB
      VmStk:        84 kB
      VmExe:       228 kB
      VmLib:      1440 kB
      VmPTE:         6 kB
      Threads:        1
      SigQ:   0/512
      SigPnd: 0000000000000000
      ShdPnd: 0000000000000000
      SigBlk: 0000000080000000
      SigIgn: 0000000000381000
      SigCgt: 0000000000004001
      CapInh: 0000000000000000
      CapPrm: 0000000000000000
      CapEff: 0000000000000000
   Nokia770-41:~# cat /proc/775/status
      Name:   dpong
      State:  S (sleeping)
      SleepAVG:       98%
      Tgid:   775
      Pid:    775
      PPid:   770
      TracerPid:      0
      Uid:    0       0       0       0
      Gid:    0       0       0       0
      FDSize: 32
      Groups: 0
      VmSize:     3196 kB
      VmLck:         0 kB
      VmRSS:       940 kB
      VmData:      472 kB
      VmStk:        84 kB
      VmExe:         8 kB
      VmLib:      2308 kB
      VmPTE:         8 kB
      Threads:        1
      SigQ:   22/512
      SigPnd: 0000000000000000
      ShdPnd: 0000000000000000
      SigBlk: 0000000080000000
      SigIgn: 0000000000001000
      SigCgt: 0000000380000000
      CapInh: 0000000000000000
      CapPrm: 00000000fffffeff
      CapEff: 00000000fffffeff
   Nokia770-41:~# cat /proc/782/status
      Name:   dping
      State:  R (running)
      SleepAVG:       0%
      Tgid:   782
      Pid:    782
      PPid:   776
      TracerPid:      0
      Uid:    0       0       0       0
      Gid:    0       0       0       0
      FDSize: 32
      Groups: 0
      VmSize:     3188 kB
      VmLck:         0 kB
      VmRSS:       800 kB
      VmData:      468 kB
      VmStk:        84 kB
      VmExe:         4 kB
      VmLib:      2308 kB
      VmPTE:         8 kB
      Threads:        1
      SigQ:   22/512
      SigPnd: 0000000000000000
      ShdPnd: 0000000000000000
      SigBlk: 0000000080000000
      SigIgn: 0000000000001000
      SigCgt: 0000000380000000
      CapInh: 0000000000000000
      CapPrm: 00000000fffffeff
      CapEff: 00000000fffffeff