bcc-biotop(8)

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

6       biotop - Block device (disk) I/O by process top.
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SYNOPSIS

9       biotop [-h] [-C] [-r MAXROWS] [interval] [count]
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DESCRIPTION

12       This is top for disks.
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14       This  traces block device I/O (disk I/O), and prints a per-process sum‐
15       mary every interval (by default, 1 second). The summary  is  sorted  on
16       the top disk consumers by throughput (Kbytes). The PID and process name
17       shown are measured from when the I/O was first created,  which  usually
18       identifies the responsible process.
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20       For  efficiency, this uses in-kernel eBPF maps to cache process details
21       (PID and comm) by I/O request, as well as a starting timestamp for cal‐
22       culating I/O latency, and the final summary.
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24       This  works  by  tracing various kernel blk_*() functions using dynamic
25       tracing, and will need updating to match any  changes  to  these  func‐
26       tions.
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28       Since this uses BPF, only the root user can use this tool.
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REQUIREMENTS

31       CONFIG_BPF and bcc.
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OPTIONS

34       -C     Don't clear the screen.
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36       -r MAXROWS
37              Maximum number of rows to print. Default is 20.
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39       -p PID Trace this PID only.
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41       interval
42              Interval between updates, seconds.
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44       count  Number of interval summaries.
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EXAMPLES

47       Summarize block device I/O by process, 1 second screen refresh:
48              # biotop
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50       Don't clear the screen:
51              # biotop -C
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53       5 second summaries, 10 times only:
54              # biotop 5 10
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FIELDS

57       loadavg:
58              The contents of /proc/loadavg
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60       PID    Cached  process  ID, if present. This usually (but isn't guaran‐
61              teed) to identify the responsible process for the I/O.
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63       COMM   Cached process name, if present. This usually (but isn't guaran‐
64              teed) to identify the responsible process for the I/O.
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66       D      Direction: R == read, W == write. This is a simplification.
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68       MAJ    Major device number.
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70       MIN    Minor device number.
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72       DISK   Disk device name.
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74       I/O    Number of I/O during the interval.
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76       Kbytes Total Kbytes for these I/O, during the interval.
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78       AVGms  Average time for the I/O (latency) from the issue to the device,
79              to its completion, in milliseconds.
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OVERHEAD

82       Since block device I/O  usually  has  a  relatively  low  frequency  (<
83       10,000/s), the overhead for this tool is expected to be low or negligi‐
84       ble. For high IOPS storage systems, test and quantify before use.
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SOURCE

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

95       Linux
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STABILITY

98       Unstable - in development.
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AUTHOR

101       Brendan Gregg
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INSPIRATION

104       top(1) by William LeFebvre
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