vfsstat(8)

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

6       vfsstat.bt - Count key VFS calls. Uses bpftrace/eBPF.
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SYNOPSIS

9       vfsstat.bt
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DESCRIPTION

12       This traces some common VFS calls and prints per-second summaries. This
13       can be useful for general workload characterization,  and  looking  for
14       patterns in operation usage over time.
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16       This  works by tracing some kernel vfs functions using dynamic tracing,
17       and will need updating to match any changes to  these  functions.  Edit
18       the  script to customize which functions are traced. Also see vfscount,
19       which is more easily customized to trace multiple functions.
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21       Since this uses BPF, only the root user can use this tool.
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REQUIREMENTS

24       CONFIG_BPF and bpftrace.
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EXAMPLES

27       Count some VFS calls, printing per-second  summaries  until  Ctrl-C  is
28       hit:
29              # vfsstat.bt
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FIELDS

32       HH:MM:SS
33              Each  output  summary  is  prefixed  by  the time of printing in
34              "HH:MM:SS" format.
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36       1st    Kernel function name (in @[])
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38       2nd    Number of calls while tracing
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OVERHEAD

41       This traces  various  kernel  vfs  functions  and  maintains  in-kernel
42       counts,  which  are asynchronously copied to user-space. While the rate
43       of VFS operations can be very high (>1M/sec), this is a relatively  ef‐
44       ficient  way  to trace these events, and so the overhead is expected to
45       be small for normal workloads.  Measure in a test environment.
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SOURCE

48       This is from bpftrace.
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50              https://github.com/iovisor/bpftrace
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52       Also look in the bpftrace distribution for  a  companion  _examples.txt
53       file containing example usage, output, and commentary for this tool.
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55       This  is  a  bpftrace version of the bcc tool of the same name. The bcc
56       tool may provide more options and customizations.
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58              https://github.com/iovisor/bcc
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OS

61       Linux
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STABILITY

64       Unstable - in development.
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AUTHOR

67       Brendan Gregg
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