vfscount(8)

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

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

9       vfscount.bt
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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 bpftrace.
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EXAMPLES

25       Count all VFS calls until Ctrl-C is hit:
26              # vfscount.bt
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FIELDS

29       1st    Kernel function name (in @[])
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31       2nd    Number of calls while tracing
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OVERHEAD

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

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

56       Linux
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STABILITY

59       Unstable - in development.
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AUTHOR

62       Brendan Gregg
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