Openmoko Bug #2320: icmp ping RTT over wifi plotted over time forms a sawtooth wave

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Openmoko Bug #2320: icmp ping RTT over wifi plotted over time forms a sawtooth wave

Openmoko Public Trac
#2320: icmp ping RTT over wifi plotted over time forms a sawtooth wave
-----------------------------+----------------------------------------------
 Reporter:  lindi            |          Owner:  openmoko-kernel    
     Type:  defect           |         Status:  new                
 Priority:  normal           |      Milestone:                    
Component:  System Software  |        Version:  unspecified        
 Severity:  normal           |       Keywords:  wifi latency kernel
 Haspatch:  0                |      Blockedby:                    
Estimated:                   |    Patchreview:                    
 Blocking:                   |   Reproducible:  always            
-----------------------------+----------------------------------------------
 icmp ping over wifi seems to show very peculiar delays that increase by
 around 10 ms on every attempt and at some point reset back to 20 ms:

 {{{
 $ ping 192.168.2.1
 64 bytes from 192.168.2.1: icmp_seq=29 ttl=64 time=20.1 ms
 64 bytes from 192.168.2.1: icmp_seq=30 ttl=64 time=40.1 ms
 64 bytes from 192.168.2.1: icmp_seq=31 ttl=64 time=60.1 ms
 64 bytes from 192.168.2.1: icmp_seq=32 ttl=64 time=80.3 ms
 64 bytes from 192.168.2.1: icmp_seq=33 ttl=64 time=90.3 ms
 64 bytes from 192.168.2.1: icmp_seq=34 ttl=64 time=110 ms
 64 bytes from 192.168.2.1: icmp_seq=35 ttl=64 time=30.1 ms
 64 bytes from 192.168.2.1: icmp_seq=36 ttl=64 time=50.1 ms
 64 bytes from 192.168.2.1: icmp_seq=37 ttl=64 time=70.1 ms
 64 bytes from 192.168.2.1: icmp_seq=38 ttl=64 time=90.2 ms
 64 bytes from 192.168.2.1: icmp_seq=39 ttl=64 time=109 ms
 64 bytes from 192.168.2.1: icmp_seq=40 ttl=64 time=20.1 ms
 64 bytes from 192.168.2.1: icmp_seq=41 ttl=64 time=40.1 ms
 64 bytes from 192.168.2.1: icmp_seq=42 ttl=64 time=60.1 ms
 64 bytes from 192.168.2.1: icmp_seq=43 ttl=64 time=85.5 ms
 64 bytes from 192.168.2.1: icmp_seq=44 ttl=64 time=104 ms
 64 bytes from 192.168.2.1: icmp_seq=45 ttl=64 time=115 ms
 64 bytes from 192.168.2.1: icmp_seq=46 ttl=64 time=447 ms
 64 bytes from 192.168.2.1: icmp_seq=47 ttl=64 time=770 ms
 64 bytes from 192.168.2.1: icmp_seq=48 ttl=64 time=380 ms
 64 bytes from 192.168.2.1: icmp_seq=49 ttl=64 time=90.2 ms
 64 bytes from 192.168.2.1: icmp_seq=50 ttl=64 time=110 ms
 64 bytes from 192.168.2.1: icmp_seq=51 ttl=64 time=30.1 ms
 64 bytes from 192.168.2.1: icmp_seq=52 ttl=64 time=50.1 ms
 64 bytes from 192.168.2.1: icmp_seq=53 ttl=64 time=70.1 ms
 64 bytes from 192.168.2.1: icmp_seq=54 ttl=64 time=90.2 ms
 64 bytes from 192.168.2.1: icmp_seq=55 ttl=64 time=100 ms
 64 bytes from 192.168.2.1: icmp_seq=56 ttl=64 time=21.5 ms
 64 bytes from 192.168.2.1: icmp_seq=57 ttl=64 time=40.1 ms
 64 bytes from 192.168.2.1: icmp_seq=58 ttl=64 time=60.0 ms
 64 bytes from 192.168.2.1: icmp_seq=59 ttl=64 time=80.3 ms
 64 bytes from 192.168.2.1: icmp_seq=60 ttl=64 time=100 ms
 64 bytes from 192.168.2.1: icmp_seq=61 ttl=64 time=120 ms
 64 bytes from 192.168.2.1: icmp_seq=62 ttl=64 time=30.1 ms
 64 bytes from 192.168.2.1: icmp_seq=63 ttl=64 time=50.0 ms
 64 bytes from 192.168.2.1: icmp_seq=64 ttl=64 time=70.1 ms
 64 bytes from 192.168.2.1: icmp_seq=65 ttl=64 time=90.2 ms
 64 bytes from 192.168.2.1: icmp_seq=66 ttl=64 time=110 ms
 64 bytes from 192.168.2.1: icmp_seq=67 ttl=64 time=30.1 ms
 64 bytes from 192.168.2.1: icmp_seq=68 ttl=64 time=50.0 ms
 64 bytes from 192.168.2.1: icmp_seq=69 ttl=64 time=60.0 ms
 64 bytes from 192.168.2.1: icmp_seq=70 ttl=64 time=80.3 ms
 64 bytes from 192.168.2.1: icmp_seq=71 ttl=64 time=100 ms
 64 bytes from 192.168.2.1: icmp_seq=72 ttl=64 time=20.1 ms
 64 bytes from 192.168.2.1: icmp_seq=73 ttl=64 time=40.1 ms
 64 bytes from 192.168.2.1: icmp_seq=74 ttl=64 time=60.1 ms
 }}}

 linux is andy-tracking a3587e4ed77974ad
 hardware is gta02v5
 tested with two WLAN APs, one is wrt54gl v1.1 running openwrt svn r18459
 with b43 driver and the other one is unknown.

 Is something buffering the packets?

 Since ping measures RTT I used

 nc -lp1234 -u | perl -e 'use Time::HiRes; $| = 1; while (<>) {
 $l=Time::HiRes::time() - $_; $l*=1000;print "$l\n"; }'
 perl -e 'use Time::HiRes; $| = 1; while (1) { print Time::HiRes::time() .
 "\n"; sleep(1); }' | nc -u 192.168.0.99 1234

 to measure delay from PC to openmoko

 {{{
 12.293959
 12.502098
 12.347841
 11.870050
 11.975908
 11.922026
 12.448931
 11.515045
 12.295866
 11.923933
 11.738920
 11.603022
 11.639023
 11.248970
 26.214981
 11.125946
 11.755848
 10.733032
 11.644983
 11.251116
 11.290932
 11.272812
 11.109018
 11.723185
 11.438990
 11.480951
 11.324072
 11.042976
 11.093998
 10.823870
 14.966869
 18.019819
 }}}

 and openmoko to PC

 {{{
 128.469002
 129.320871
 128.603947
 128.538143
 128.767979
 128.843081
 136.215937
 133.112204
 137.031090
 128.907930
 128.802073
 128.696215
 128.594887
 129.487049
 129.377853
 129.401934
 129.205000
 129.066002
 128.966105
 128.860008
 129.772913
 129.657042
 137.234938
 129.427921
 129.323017
 129.232895
 130.115997
 130.011093
 130.097162
 129.807007
 129.707109
 129.714024
 129.505884
 }}}

 The absolute values mean nothing since the clocks are not entirely in
 sync. However, we can see here that this test does not show the same
 variations as we see with ping. What an earth could be going on here? If I
 ping with shorter interval the delay seems to stick to some value that is
 different on each attempt:

 {{{
 lindi@ginger:~$ ping -i 0.2 192.168.2.1
 PING 192.168.2.1 (192.168.2.1) 56(84) bytes of data.
 64 bytes from 192.168.2.1: icmp_seq=1 ttl=64 time=87.4 ms
 64 bytes from 192.168.2.1: icmp_seq=2 ttl=64 time=90.2 ms
 64 bytes from 192.168.2.1: icmp_seq=3 ttl=64 time=90.1 ms
 64 bytes from 192.168.2.1: icmp_seq=4 ttl=64 time=90.1 ms
 64 bytes from 192.168.2.1: icmp_seq=5 ttl=64 time=90.1 ms
 64 bytes from 192.168.2.1: icmp_seq=6 ttl=64 time=90.1 ms
 64 bytes from 192.168.2.1: icmp_seq=7 ttl=64 time=90.3 ms
 64 bytes from 192.168.2.1: icmp_seq=8 ttl=64 time=90.1 ms
 64 bytes from 192.168.2.1: icmp_seq=9 ttl=64 time=90.0 ms
 64 bytes from 192.168.2.1: icmp_seq=10 ttl=64 time=90.1 ms
 64 bytes from 192.168.2.1: icmp_seq=11 ttl=64 time=90.1 ms
 }}}
 {{{
 lindi@ginger:~$ ping -i 0.2 192.168.2.1
 PING 192.168.2.1 (192.168.2.1) 56(84) bytes of data.
 64 bytes from 192.168.2.1: icmp_seq=1 ttl=64 time=32.1 ms
 64 bytes from 192.168.2.1: icmp_seq=2 ttl=64 time=35.4 ms
 64 bytes from 192.168.2.1: icmp_seq=3 ttl=64 time=35.3 ms
 64 bytes from 192.168.2.1: icmp_seq=4 ttl=64 time=35.3 ms
 64 bytes from 192.168.2.1: icmp_seq=5 ttl=64 time=35.3 ms
 64 bytes from 192.168.2.1: icmp_seq=6 ttl=64 time=35.3 ms
 64 bytes from 192.168.2.1: icmp_seq=7 ttl=64 time=35.3 ms
 64 bytes from 192.168.2.1: icmp_seq=8 ttl=64 time=40.1 ms
 64 bytes from 192.168.2.1: icmp_seq=9 ttl=64 time=40.1 ms
 }}}
 {{{
 lindi@ginger:~$ ping -i 0.2 192.168.2.1
 PING 192.168.2.1 (192.168.2.1) 56(84) bytes of data.
 64 bytes from 192.168.2.1: icmp_seq=1 ttl=64 time=108 ms
 64 bytes from 192.168.2.1: icmp_seq=2 ttl=64 time=110 ms
 64 bytes from 192.168.2.1: icmp_seq=3 ttl=64 time=110 ms
 64 bytes from 192.168.2.1: icmp_seq=4 ttl=64 time=110 ms
 64 bytes from 192.168.2.1: icmp_seq=5 ttl=64 time=110 ms
 64 bytes from 192.168.2.1: icmp_seq=6 ttl=64 time=110 ms
 64 bytes from 192.168.2.1: icmp_seq=7 ttl=64 time=110 ms
 64 bytes from 192.168.2.1: icmp_seq=8 ttl=64 time=105 ms
 64 bytes from 192.168.2.1: icmp_seq=9 ttl=64 time=110 ms
 64 bytes from 192.168.2.1: icmp_seq=10 ttl=64 time=110 ms
 64 bytes from 192.168.2.1: icmp_seq=11 ttl=64 time=110 ms
 64 bytes from 192.168.2.1: icmp_seq=12 ttl=64 time=110 ms
 64 bytes from 192.168.2.1: icmp_seq=13 ttl=64 time=110 ms
 }}}

--
Ticket URL: <https://docs.openmoko.org/trac/ticket/2320>
docs.openmoko.org <http://docs.openmoko.org/trac/>
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Re: Openmoko Bug #2320: icmp ping RTT over wifi plotted over time forms a sawtooth wave

Openmoko Public Trac
#2320: icmp ping RTT over wifi plotted over time forms a sawtooth wave
-----------------------------+----------------------------------------------
 Reporter:  lindi            |          Owner:  openmoko-kernel    
     Type:  defect           |         Status:  new                
 Priority:  normal           |      Milestone:                    
Component:  System Software  |        Version:  unspecified        
 Severity:  normal           |       Keywords:  wifi latency kernel
 Haspatch:  0                |      Blockedby:                    
Estimated:                   |    Patchreview:                    
 Blocking:                   |   Reproducible:  always            
-----------------------------+----------------------------------------------

Comment(by lindi):

 Ping from WLAN AP to openmoko:

 {{{
 64 bytes from 192.168.2.114: seq=126 ttl=64 time=39.549 ms
 64 bytes from 192.168.2.114: seq=127 ttl=64 time=267.092 ms
 64 bytes from 192.168.2.114: seq=128 ttl=64 time=187.093 ms
 64 bytes from 192.168.2.114: seq=129 ttl=64 time=105.514 ms
 64 bytes from 192.168.2.114: seq=130 ttl=64 time=332.957 ms
 64 bytes from 192.168.2.114: seq=131 ttl=64 time=50.108 ms
 64 bytes from 192.168.2.114: seq=132 ttl=64 time=72.653 ms
 64 bytes from 192.168.2.114: seq=133 ttl=64 time=99.016 ms
 64 bytes from 192.168.2.114: seq=134 ttl=64 time=115.992 ms
 64 bytes from 192.168.2.114: seq=135 ttl=64 time=41.259 ms
 64 bytes from 192.168.2.114: seq=136 ttl=64 time=168.386 ms
 64 bytes from 192.168.2.114: seq=137 ttl=64 time=83.513 ms
 64 bytes from 192.168.2.114: seq=138 ttl=64 time=415.499 ms
 64 bytes from 192.168.2.114: seq=139 ttl=64 time=32.077 ms
 64 bytes from 192.168.2.114: seq=140 ttl=64 time=58.256 ms
 64 bytes from 192.168.2.114: seq=141 ttl=64 time=80.228 ms
 64 bytes from 192.168.2.114: seq=142 ttl=64 time=101.869 ms
 64 bytes from 192.168.2.114: seq=143 ttl=64 time=24.256 ms
 64 bytes from 192.168.2.114: seq=144 ttl=64 time=49.201 ms
 64 bytes from 192.168.2.114: seq=145 ttl=64 time=72.739 ms
 64 bytes from 192.168.2.114: seq=146 ttl=64 time=97.274 ms
 64 bytes from 192.168.2.114: seq=147 ttl=64 time=111.870 ms
 64 bytes from 192.168.2.114: seq=148 ttl=64 time=31.072 ms
 64 bytes from 192.168.2.114: seq=149 ttl=64 time=53.700 ms
 64 bytes from 192.168.2.114: seq=150 ttl=64 time=82.951 ms
 64 bytes from 192.168.2.114: seq=151 ttl=64 time=411.524 ms
 64 bytes from 192.168.2.114: seq=152 ttl=64 time=21.095 ms
 64 bytes from 192.168.2.114: seq=153 ttl=64 time=152.479 ms
 64 bytes from 192.168.2.114: seq=154 ttl=64 time=74.238 ms
 }}}

--
Ticket URL: <https://docs.openmoko.org/trac/ticket/2320#comment:1>
docs.openmoko.org <http://docs.openmoko.org/trac/>
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Re: Openmoko Bug #2320: icmp ping RTT over wifi plotted over time forms a sawtooth wave

Openmoko Public Trac
In reply to this post by Openmoko Public Trac
#2320: icmp ping RTT over wifi plotted over time forms a sawtooth wave
-----------------------------+----------------------------------------------
 Reporter:  lindi            |          Owner:  openmoko-kernel    
     Type:  defect           |         Status:  new                
 Priority:  normal           |      Milestone:                    
Component:  System Software  |        Version:  unspecified        
 Severity:  normal           |       Keywords:  wifi latency kernel
 Haspatch:  0                |      Blockedby:                    
Estimated:                   |    Patchreview:                    
 Blocking:                   |   Reproducible:  always            
-----------------------------+----------------------------------------------

Comment(by BillK):

 I would actually expect something like this when running in power saving
 mode - are you doing so? - try using wmiconfig to set maxperf and run the
 tests again.

 One powersaving technique delays transmission in conjunction with the AP
 so interactions can exist with the various timing parameters.

 BillK

--
Ticket URL: <https://docs.openmoko.org/trac/ticket/2320#comment:2>
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Re: Openmoko Bug #2320: icmp ping RTT over wifi plotted over time forms a sawtooth wave

Openmoko Public Trac
In reply to this post by Openmoko Public Trac
#2320: icmp ping RTT over wifi plotted over time forms a sawtooth wave
-----------------------------+----------------------------------------------
 Reporter:  lindi            |          Owner:  openmoko-kernel    
     Type:  defect           |         Status:  new                
 Priority:  normal           |      Milestone:                    
Component:  System Software  |        Version:  unspecified        
 Severity:  normal           |       Keywords:  wifi latency kernel
 Haspatch:  0                |      Blockedby:                    
Estimated:                   |    Patchreview:                    
 Blocking:                   |   Reproducible:  always            
-----------------------------+----------------------------------------------

Comment(by lindi):

 Ok, thanks! After ./wmiconfig -i eth0 --power maxperf I get

 {{{
 64 bytes from 192.168.2.1: icmp_seq=219 ttl=64 time=7.45 ms
 64 bytes from 192.168.2.1: icmp_seq=220 ttl=64 time=15.2 ms
 64 bytes from 192.168.2.1: icmp_seq=221 ttl=64 time=5.51 ms
 64 bytes from 192.168.2.1: icmp_seq=222 ttl=64 time=5.48 ms
 64 bytes from 192.168.2.1: icmp_seq=223 ttl=64 time=15.3 ms
 64 bytes from 192.168.2.1: icmp_seq=224 ttl=64 time=10.2 ms
 64 bytes from 192.168.2.1: icmp_seq=225 ttl=64 time=10.0 ms
 64 bytes from 192.168.2.1: icmp_seq=226 ttl=64 time=11.3 ms
 64 bytes from 192.168.2.1: icmp_seq=227 ttl=64 time=10.2 ms
 64 bytes from 192.168.2.1: icmp_seq=228 ttl=64 time=15.3 ms
 64 bytes from 192.168.2.1: icmp_seq=229 ttl=64 time=6.90 ms
 64 bytes from 192.168.2.1: icmp_seq=230 ttl=64 time=14.7 ms
 64 bytes from 192.168.2.1: icmp_seq=231 ttl=64 time=15.3 ms
 64 bytes from 192.168.2.1: icmp_seq=232 ttl=64 time=10.2 ms
 64 bytes from 192.168.2.1: icmp_seq=233 ttl=64 time=15.4 ms
 64 bytes from 192.168.2.1: icmp_seq=234 ttl=64 time=10.1 ms
 64 bytes from 192.168.2.1: icmp_seq=235 ttl=64 time=10.2 ms
 64 bytes from 192.168.2.1: icmp_seq=236 ttl=64 time=10.2 ms
 64 bytes from 192.168.2.1: icmp_seq=237 ttl=64 time=9.91 ms
 64 bytes from 192.168.2.1: icmp_seq=238 ttl=64 time=10.1 ms
 64 bytes from 192.168.2.1: icmp_seq=239 ttl=64 time=10.0 ms
 64 bytes from 192.168.2.1: icmp_seq=240 ttl=64 time=10.2 ms
 64 bytes from 192.168.2.1: icmp_seq=241 ttl=64 time=10.2 ms
 64 bytes from 192.168.2.1: icmp_seq=242 ttl=64 time=6.56 ms
 64 bytes from 192.168.2.1: icmp_seq=243 ttl=64 time=17.0 ms
 64 bytes from 192.168.2.1: icmp_seq=244 ttl=64 time=14.1 ms
 64 bytes from 192.168.2.1: icmp_seq=245 ttl=64 time=15.4 ms
 64 bytes from 192.168.2.1: icmp_seq=246 ttl=64 time=10.2 ms
 }}}

--
Ticket URL: <https://docs.openmoko.org/trac/ticket/2320#comment:3>
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Re: Openmoko Bug #2320: icmp ping RTT over wifi plotted over time forms a sawtooth wave

Openmoko Public Trac
In reply to this post by Openmoko Public Trac
#2320: icmp ping RTT over wifi plotted over time forms a sawtooth wave
-----------------------------+----------------------------------------------
 Reporter:  lindi            |          Owner:  openmoko-kernel    
     Type:  defect           |         Status:  new                
 Priority:  normal           |      Milestone:                    
Component:  System Software  |        Version:  unspecified        
 Severity:  normal           |       Keywords:  wifi latency kernel
 Haspatch:  0                |      Blockedby:                    
Estimated:                   |    Patchreview:                    
 Blocking:                   |   Reproducible:  always            
-----------------------------+----------------------------------------------

Comment(by BillK):

 I should have posted a link as well as its a standard - basic explanation
 here:
 "http://features.techworld.com/mobile-wireless/4103/a-guide-to-wi-fi-
 power-save-technologies/"

 Contrary to article, powersaving can be quite large (as it is in the
 moko).  Downside is not only the effects you noticed, but inability to
 connect to some AP's, poor performance in general, poor(er) sensitivity in
 low signal conditions and "odd things happening with the link :)"

 Usually first thing I check when a laptop does not work well over wifi, as
 it seems to often be the cause of the trouble.

 BillK

--
Ticket URL: <https://docs.openmoko.org/trac/ticket/2320#comment:4>
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Re: Openmoko Bug #2320: icmp ping RTT over wifi plotted over time forms a sawtooth wave

Openmoko Public Trac
In reply to this post by Openmoko Public Trac
#2320: icmp ping RTT over wifi plotted over time forms a sawtooth wave
------------------------------------+---------------------------------------
    Reporter:  lindi                |        Owner:  openmoko-kernel
        Type:  defect               |       Status:  closed        
    Priority:  normal               |    Milestone:                
   Component:  System Software      |      Version:  unspecified    
    Severity:  normal               |   Resolution:  wontfix        
    Keywords:  wifi latency kernel  |     Haspatch:  0              
   Blockedby:                       |    Estimated:                
 Patchreview:                       |     Blocking:                
Reproducible:  always               |  
------------------------------------+---------------------------------------
Changes (by joerg):

  * status:  new => closed
  * resolution:  => wontfix


Comment:

 closing, as it seems to be no bug according to billK

--
Ticket URL: <https://docs.openmoko.org/trac/ticket/2320#comment:5>
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Re: Openmoko Bug #2320: icmp ping RTT over wifi plotted over time forms a sawtooth wave

Openmoko Public Trac
In reply to this post by Openmoko Public Trac
#2320: icmp ping RTT over wifi plotted over time forms a sawtooth wave
------------------------------------+---------------------------------------
    Reporter:  lindi                |        Owner:  openmoko-kernel
        Type:  defect               |       Status:  closed        
    Priority:  normal               |    Milestone:                
   Component:  System Software      |      Version:  unspecified    
    Severity:  normal               |   Resolution:  wontfix        
    Keywords:  wifi latency kernel  |     Haspatch:  0              
   Blockedby:                       |    Estimated:                
 Patchreview:                       |     Blocking:                
Reproducible:  always               |  
------------------------------------+---------------------------------------

Comment(by lindi):

 Shouldn't resolution be INVALID since this was not a bug? wontfix would
 make people think this was a bug but it just won't be fixed. (Or is
 invalid not available as an option in trac?)

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Ticket URL: <https://docs.openmoko.org/trac/ticket/2320#comment:6>
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