NAME

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

SYNOPSIS

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

DESCRIPTION

       this tool measures tcp sockets congestion control status duration, and prints a summary of tcp congestion
       state durations along with the number of total state changes.

       It  uses dynamic tracing of kernel tcp congestion control status updating functions,  and will need to be
       updated to match kernel changes.

       The traced functions are only called when there is  congestion  state  update,  and  therefore  have  low
       overhead.  we also use BPF map to store traced data to reduce overhead. See the OVERHEAD section for more
       details.  Since this uses BPF, only the root user can use this tool.

REQUIREMENTS

       CONFIG_BPF and bcc.

OPTIONS

       -h     Print usage message.

       -T     Include a timestamp column.

       -L     Specify local tcp port range.

       -R     Specify remote tcp port range.

       -u     Output in microseconds.

       -d     Show congestion status duration distribution as histograms.

EXAMPLES

       Show all tcp sockets congestion status duration until Ctrl-C:
              # tcpcongestdura

       Show all tcp sockets congestion status duration every 1 second and 10 times:
              # tcpcong 1 10

       Show only local port 3000-3006 congestion status duration every 1 second:
              # tcpcong -L 3000-3006 1

       Show only remote port 5000-5005 congestion status duration every 1 second:
              # tcpcong -R 5000-5005 1

       Show 1 second summaries, printed in microseconds, with timestamps:
              # tcpcong -uT 1

       Show all tcp sockets congestion status duration as histograms:
              # tcpcong -d

FIELDS

       LAddrPort
              local ip address and tcp socket port.

       RAddrPort
              remote ip address and tcp socket port.

       Open_us
              Total duration in open status for microseconds.

       Dod_us Total duration in disorder status for microseconds.

       Rcov_us
              Total duration in recovery status for microseconds.

       Cwr_us Total duration in cwr status for microseconds.

       Los_us Total duration in loss status for microseconds.

       Open_ms
              Total duration in open status for milliseconds.

       Dod_ms Total duration in disorder status for milliseconds.

       Rcov_ms
              Total duration in recovery status for milliseconds.

       Cwr_ms Total duration in cwr status for milliseconds.

       Loss_ms
              Total duration in loss status for milliseconds.

       Chgs   Total number of status change.

       usecs  Range of microseconds for this bucket.

       msecs  Range of milliseconds for this bucket.

       count  Number of congestion status in this time range.

       distribution
              ASCII representation of the distribution (the count column).

OVERHEAD

       This traces the kernel tcp congestion status change functions.   As  called  rate  per  second  of  these
       functions  per  socket  is  low(<10000),  the  overhead is also expected to be negligible. If you have an
       application that will create thousands of tcp connections, then test and understand overhead before use.

SOURCE

       This is from bcc.

              https://github.com/iovisor/bcc

       Also look in the bcc distribution for a companion _examples.txt file containing  example  usage,  output,
       and commentary for this tool.

OS

       Linux

STABILITY

       Unstable - in development.

AUTHOR

       jacky gan

SEE ALSO

       tcpretrans(8), tcpconnect(8), tcptop(8), tcpdrop(8)

USER COMMANDS                                      2022-01-27                                         tcpcong(8)