xfsdist(8)

1xfsdist(8)                  System Manager's Manual                 xfsdist(8)
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NAME

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

9       xfsdist.bt
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DESCRIPTION

12       This  tool  summarizes  time  (latency) spent in common XFS file opera‐
13       tions: reads, writes, opens, and syncs, and presents it as a power-of-2
14       histogram. It uses an in-kernel eBPF map to store the histogram for ef‐
15       ficiency.
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17       Since this works by tracing  the  xfs_file_operations  interface  func‐
18       tions, it will need updating to match any changes to these functions.
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20       Since this uses BPF, only the root user can use this tool.
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REQUIREMENTS

23       CONFIG_BPF and bpftrace.
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EXAMPLES

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

30       0th    The  operation  name  (shown in "@[...]") is printed before each
31              I/O histogram.
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33       1st, 2nd
34              This is a range of latency, in microseconds  (shown  in  "[...)"
35              set notation).
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37       3rd    A column showing the count of operations in this range.
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39       4th    This is an ASCII histogram representing the count column.
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OVERHEAD

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

49       This is from bpftrace.
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51              https://github.com/iovisor/bpftrace
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53       Also  look  in  the bpftrace distribution for a companion _examples.txt
54       file containing example usage, output, and commentary for this tool.
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56       This is a bpftrace version of the bcc tool of the same  name.  The  bcc
57       tool may provide more options and customizations.
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59              https://github.com/iovisor/bcc
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OS

62       Linux
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STABILITY

65       Unstable - in development.
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AUTHOR

68       Brendan Gregg
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