---
name: "vfscount-bpfcc"
section: "8"
platform: "linux"
package: "bpfcc-tools"
version: "0.31.0+ds-7"
release: "Debian 13 (Trixie)"
platforms: ["linux"]
url: "https://new.carta.tech/vfscount-bpfcc"
---

# vfscount-bpfcc(8)

Count VFS calls ("vfs\_\*"). Uses Linux eBPF/bcc.

## NAME

vfscount - Count VFS calls ("vfs\_\*"). Uses Linux eBPF/bcc.

## SYNOPSIS

**vfscount \[duration\]**

## DESCRIPTION

This counts VFS calls. This can be useful for general workload characterization 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 bcc.

## OPTIONS

- duration

  duration of the trace in seconds.

## EXAMPLES

- Count some VFS calls until Ctrl-C is hit:

  \# **vfscount**

- Count some VFS calls in ten seconds

  \# **vfscount 10**

## FIELDS

- ADDR

  Address of the instruction pointer that was traced (only useful if the FUNC column is suspicious and you would like to double check the translation).

- FUNC

  Kernel function name

- COUNT

  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 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, 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 bcc.

-

  https://github.com/iovisor/bcc

Also look in the bcc distribution for a companion \_examples.txt file containing example usage, output, and commentary for this tool.

## OS

Linux

## STABILITY

Unstable - in development.

## AUTHOR

Brendan Gregg

## SEE ALSO

vfsstat(8)