Manual: xfsdist.bt

xfsdist.bt(8)					   System Manager's Manual				       xfsdist.bt(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  over‐
       head of this tool may become noticeable.	 Measure and quantify before use.

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 com‐
       mentary for this tool.

       This is a bpftrace version of the bcc tool of the same name. The bcc tool may provide  more  options  and  customiza‐
       tions.

	      https://github.com/iovisor/bcc

OS
       Linux

STABILITY
       Unstable - in development.

AUTHOR
       Brendan Gregg

SEE ALSO
       biolatency.bt(8)

USER COMMANDS						 2018-09-08					       xfsdist.bt(8)