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)