vfscount.bt(8) System Manager's Manual vfscount.bt(8)
NAME
vfscount.bt - Count VFS calls ("vfs_*"). Uses bpftrace/eBPF.
SYNOPSIS
vfscount.bt
DESCRIPTION
This counts VFS calls. This can be useful for general workload charac-
terization of these operations.
This works by tracing all kernel functions beginning with "vfs_" using
dynamic tracing. This may match more functions than you are interested
in measuring: Edit the script to customize which functions to trace.
Since this uses BPF, only the root user can use this tool.
REQUIREMENTS
CONFIG_BPF and bpftrace.
EXAMPLES
Count all VFS calls until Ctrl-C is hit:
# vfscount.bt
FIELDS
1st Kernel function name (in @[])
2nd Number of calls while tracing
OVERHEAD
This traces kernel vfs functions and maintains in-kernel counts, which
are asynchronously copied to user-space. While the rate of VFS opera-
tions 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, and if overheads are
an issue, edit the script to reduce the types of vfs functions traced
(currently all beginning with "vfs_").
SOURCE
This is from bpftrace.
https://github.com/iovisor/bpftrace
Also look in the bpftrace distribution for a companion _examples.txt
file containing example usage, output, and commentary for this tool.
This is a bpftrace version of the bcc tool of the same name. The bcc
tool may provide more options and customizations.
https://github.com/iovisor/bcc
OS
Linux
STABILITY
Unstable - in development.
AUTHOR
Brendan Gregg
SEE ALSO
vfsstat.bt(8)
USER COMMANDS 2018-09-06 vfscount.bt(8)
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