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xfsdist-bpfcc(8)


NAME

   xfsdist - Summarize XFS operation latency. Uses Linux eBPF/bcc.

SYNOPSIS

   xfsdist [-h] [-T] [-N] [-d] [interval] [count]

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 bcc.

OPTIONS

   -h     Print usage message.

   -T     Don't include timestamps on interval output.

   -m     Output in milliseconds.

   -p PID Trace this PID only.

EXAMPLES

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

   Trace PID 181 only:
          # xfsdist -p 181

   Print 1 second summaries, 10 times:
          # xfsdist 1 10

   1 second summaries, printed in milliseconds
          # xfsdist -m 1

FIELDS

   msecs  Range of milliseconds for this bucket.

   usecs  Range of microseconds for this bucket.

   count  Number of operations in this time range.

   distribution
          ASCII representation of the distribution (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 bcc.

          https://github.com/iovisor/bcc

   Also look in the bcc distribution for a  companion  _examples.txt  file
   containing example usage, output, and commentary for this tool.

OS

   Linux

STABILITY

   Unstable - in development.

AUTHOR

   Brendan Gregg

SEE ALSO

   xfssnoop(8)



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