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

# [NAME](#NAME)

xfsdist.bt - Summarize XFS operation latency. Uses bpftrace/eBPF.

# [SYNOPSIS](#SYNOPSIS)

**xfsdist.bt**

# [DESCRIPTION](#DESCRIPTION)

This tool summarizes time (latency) spent in common XFS file operations: reads, writes, opens, and syncs, and presents it as a power-of-2 histogram. It uses an in-kernel eBPF map to store the histogram for efficiency.

Since this works by tracing the xfs\_file\_operations interface functions, it will need updating to match any changes to these functions.

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

# [REQUIREMENTS](#REQUIREMENTS)

CONFIG\_BPF and bpftrace.

# [EXAMPLES](#EXAMPLES)

[Trace XFS operation time, and print a summary on Ctrl-C:](#Trace)

\# **xfsdist.bt**

# [FIELDS](#FIELDS)

0th

The operation name (shown in "@\[...]") is printed before each I/O histogram.

1st, 2nd

This is a range of latency, in microseconds (shown in "[...)" set notation).

3rd

A column showing the count of operations in this range.

4th

This is an ASCII histogram representing the count column.

# [OVERHEAD](#OVERHEAD)

This adds low-overhead instrumentation to these XFS operations, including reads and writes from the file system cache. Such reads and writes can be very frequent (depending on the workload; eg, 1M/sec), at which point the overhead of this tool may become noticeable. Measure and quantify before use.

# [SOURCE](#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 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](#OS)

Linux

# [STABILITY](#STABILITY)

Unstable - in development.

# [AUTHOR](#AUTHOR)

Brendan Gregg

# [SEE ALSO](#SEE_ALSO)

[biolatency.bt(8)](/man/enterprise-packages/bpftrace/biolatency.bt.8)

2018-09-08 USER COMMANDS

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Document: xfsdist.bt(8) from bpftrace 0.27.0-r1 (Chainguard OS)
Source: https://github.com/bpftrace/bpftrace