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)