bcc-vfscount(8)

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

6       vfscount - Count VFS calls ("vfs_*"). Uses Linux eBPF/bcc.
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SYNOPSIS

9       vfscount [duration]
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DESCRIPTION

12       This  counts VFS calls. This can be useful for general workload charac‐
13       terization of these operations.
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15       This works by tracing all kernel functions beginning with "vfs_"  using
16       dynamic  tracing. This may match more functions than you are interested
17       in measuring: Edit the script to customize which functions to trace.
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19       Since this uses BPF, only the root user can use this tool.
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REQUIREMENTS

22       CONFIG_BPF and bcc.
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OPTIONS

25       duration
26              duration of the trace in seconds.
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EXAMPLES

29       Count some VFS calls until Ctrl-C is hit:
30              # vfscount
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32       Count some VFS calls in ten seconds
33              # vfscount 10
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FIELDS

36       ADDR   Address of the instruction pointer that was traced (only  useful
37              if  the  FUNC  column is suspicious and you would like to double
38              check the translation).
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40       FUNC   Kernel function name
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42       COUNT  Number of calls while tracing
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OVERHEAD

45       This traces kernel vfs functions and maintains in-kernel counts,  which
46       are  asynchronously  copied to user-space. While the rate of VFS opera‐
47       tions can be very high (>1M/sec), this is a relatively efficient way to
48       trace  these  events,  and  so the overhead is expected to be small for
49       normal workloads.  Measure in a test environment, and if overheads  are
50       an  issue,  edit the script to reduce the types of vfs functions traced
51       (currently all beginning with "vfs_").
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SOURCE

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

62       Linux
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STABILITY

65       Unstable - in development.
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AUTHOR

68       Brendan Gregg
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