xfsdist(8)

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

SYNOPSIS
xfsdist.bt

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
CONFIG_BPF and bpftrace.

EXAMPLES

Trace XFS operation time, and print a summary on Ctrl-C:
    # xfsdist.bt

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
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
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
biolatency(8)