bcc-tcptop(8)

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

6       tcptop - Summarize TCP send/recv throughput by host. Top for TCP.
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SYNOPSIS

9       tcptop [-h] [-C] [-S] [-p PID] [interval] [count]
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DESCRIPTION

12       This is top for TCP sessions.
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14       This  summarizes  TCP send/receive Kbytes by host, and prints a summary
15       that refreshes, along other system-wide metrics.
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17       This uses dynamic tracing of kernel  TCP  send/receive  functions,  and
18       will need to be updated to match kernel changes.
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20       The  traced  TCP functions are usually called at a lower rate than per-
21       packet functions, and therefore have lower overhead. The traced data is
22       summarized  in-kernel  using  a  BPF map to further reduce overhead. At
23       very high TCP event rates, the overhead may still  be  measurable.  See
24       the OVERHEAD section for more details.
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26       Since this uses BPF, only the root user can use this tool.
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REQUIREMENTS

29       CONFIG_BPF and bcc.
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OPTIONS

32       -h     Print USAGE message.
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34       -C     Don't clear the screen.
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36       -S     Don't print the system summary line (load averages).
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38       -p PID Trace this PID only.
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40       interval
41              Interval between updates, seconds (default 1).
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43       count  Number of interval summaries (default is many).
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EXAMPLES

46       Summarize TCP throughput by active sessions, 1 second refresh:
47              # tcptop
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49       Don't clear the screen (rolling output), and 5 second summaries:
50              # tcptop -C 5
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52       Trace PID 181 only, and don't clear the screen:
53              # tcptop -Cp 181
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FIELDS

56       loadavg:
57              The contents of /proc/loadavg
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59       PID    Process ID.
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61       COMM   Process name.
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63       LADDR  Local address (IPv4), and TCP port
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65       RADDR  Remote address (IPv4), and TCP port
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67       LADDR6 Source address (IPv6), and TCP port
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69       RADDR6 Destination address (IPv6), and TCP port
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71       RX_KB  Received Kbytes
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73       TX_KB  Transmitted Kbytes
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OVERHEAD

76       This  traces  all send/receives in TCP, high in the TCP/IP stack (close
77       to the application) which are usually called at a lower rate than  per-
78       packet  functions, lowering overhead. It also summarizes data in-kernel
79       to further reduce overhead. These techniques help, but there may  still
80       be  measurable overhead at high send/receive rates, eg, ~13% of one CPU
81       at 100k events/sec.  use funccount to count the kprobes in the tool  to
82       find  out this rate, as the overhead is relative to the rate. Some sam‐
83       ple production servers tested found total TCP event rates of 4k to  15k
84       per  second,  and  the  CPU overhead at these rates ranged from 0.5% to
85       2.0% of one CPU. If your send/receive rate is low (eg, <1000/sec)  then
86       the  overhead  is  expected to be negligible; Test in a lab environment
87       first.
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SOURCE

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

98       Linux
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STABILITY

101       Unstable - in development.
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AUTHOR

104       Brendan Gregg
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INSPIRATION

107       top(1) by William LeFebvre
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