bcc-tcpcong(8)

1tcpcong(8)                  System Manager's Manual                 tcpcong(8)
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NAME

6       tcpcong - Measure tcp congestion state duration. Uses Linux eBPF/bcc.
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SYNOPSIS

9       tcpcong [-h] [-T] [-L] [-R] [-u] [-d] [interval] [outputs]
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DESCRIPTION

12       this  tool measures tcp sockets congestion control status duration, and
13       prints a summary of tcp congestion state durations along with the  num‐
14       ber of total state changes.
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16       It  uses dynamic tracing of kernel tcp congestion control status updat‐
17       ing functions,  and will need to be updated to match kernel changes.
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19       The traced functions are only called when there is congestion state up‐
20       date,  and  therefore  have  low overhead. we also use BPF map to store
21       traced data to reduce overhead. See the OVERHEAD section for  more  de‐
22       tails.  Since this uses BPF, only the root user can use this tool.
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REQUIREMENTS

25       CONFIG_BPF and bcc.
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OPTIONS

28       -h     Print usage message.
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30       -T     Include a timestamp column.
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32       -L     Specify local tcp port range.
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34       -R     Specify remote tcp port range.
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36       -u     Output in microseconds.
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38       -d     Show congestion status duration distribution as histograms.
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EXAMPLES

41       Show all tcp sockets congestion status duration until Ctrl-C:
42              # tcpcongestdura
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44       Show  all  tcp sockets congestion status duration every 1 second and 10
45       times:
46              # tcpcong 1 10
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48       Show only local port 3000-3006 congestion status duration every 1  sec‐
49       ond:
50              # tcpcong -L 3000-3006 1
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52       Show only remote port 5000-5005 congestion status duration every 1 sec‐
53       ond:
54              # tcpcong -R 5000-5005 1
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56       Show 1 second summaries, printed in microseconds, with timestamps:
57              # tcpcong -uT 1
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59       Show all tcp sockets congestion status duration as histograms:
60              # tcpcong -d
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FIELDS

63       LAddrPort
64              local ip address and tcp socket port.
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66       RAddrPort
67              remote ip address and tcp socket port.
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69       Open_us
70              Total duration in open status for microseconds.
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72       Dod_us Total duration in disorder status for microseconds.
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74       Rcov_us
75              Total duration in recovery status for microseconds.
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77       Cwr_us Total duration in cwr status for microseconds.
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79       Los_us Total duration in loss status for microseconds.
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81       Open_ms
82              Total duration in open status for milliseconds.
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84       Dod_ms Total duration in disorder status for milliseconds.
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86       Rcov_ms
87              Total duration in recovery status for milliseconds.
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89       Cwr_ms Total duration in cwr status for milliseconds.
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91       Loss_ms
92              Total duration in loss status for milliseconds.
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94       Chgs   Total number of status change.
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96       usecs  Range of microseconds for this bucket.
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98       msecs  Range of milliseconds for this bucket.
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100       count  Number of congestion status in this time range.
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102       distribution
103              ASCII representation of the distribution (the count column).
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OVERHEAD

106       This traces the kernel tcp  congestion  status  change  functions.   As
107       called  rate  per  second of these functions per socket is low(<10000),
108       the overhead is also expected to be negligible. If you have an applica‐
109       tion  that  will create thousands of tcp connections, then test and un‐
110       derstand overhead before use.
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SOURCE

113       This is from bcc.
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115              https://github.com/iovisor/bcc
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117       Also look in the bcc distribution for a  companion  _examples.txt  file
118       containing example usage, output, and commentary for this tool.
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OS

121       Linux
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STABILITY

124       Unstable - in development.
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AUTHOR

127       jacky gan
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