Manual: vfsstat.bt

vfsstat.bt(8)					   System Manager's Manual				       vfsstat.bt(8)

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

SYNOPSIS
       vfsstat.bt

DESCRIPTION
       This traces some common VFS calls and prints per-second summaries. This can be useful for general workload character‐
       ization, and looking for patterns in operation usage over time.

       This works by tracing some kernel vfs functions using dynamic tracing, and will need updating to match any changes to
       these  functions.  Edit	the  script to customize which functions are traced. Also see vfscount, which is more easily
       customized to trace multiple functions.

       Since this uses BPF, only the root user can use this tool.

REQUIREMENTS
       CONFIG_BPF and bpftrace.

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

FIELDS
       HH:MM:SS
	      Each output summary is prefixed by the time of printing in "HH:MM:SS" format.

       1st    Kernel function name (in @[])

       2nd    Number of calls while tracing

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

SOURCE
       This is from bpftrace.

	      https://github.com/bpftrace/bpftrace

       Also  look in the bpftrace distribution for a companion _examples.txt file containing example usage, output, and com‐
       mentary for this tool.

       This is a bpftrace version of the bcc tool of the same name. The bcc tool may provide  more  options  and  customiza‐
       tions.

	      https://github.com/iovisor/bcc

OS
       Linux

STABILITY
       Unstable - in development.

AUTHOR
       Brendan Gregg

SEE ALSO
       vfscount.bt(8)

USER COMMANDS						 2018-09-06					       vfsstat.bt(8)