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

6       fdrd - Flight Data Recorder daemon
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SYNOPSIS

9       /usr/bin/fdrd
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DESCRIPTION

12       The  fdrd  program  is  a  daemon which enables ftrace probes, harvests
13       ftrace data and (optionally) writes the data to a file.
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15       The behavior of  fdr  is  defined  by  configuration  files  stored  in
16       /etc/fdr.d.   During service startup, fdr will process each file in the
17       directory which has the suffix of .conf.  If new config files are added
18       to the fdr.d directory, then the service must be restarted to recognize
19       the new configuration information.
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21       fdr is controlled by systemd (8) on systems where systemd is available.
22       Error messages from fdr can be viewed via systemctl, for example,
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24       systemctl status -l fdr
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Configuration File Syntax

27       The following keywords and options are recognized
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29       instance iname [buffer-size]
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31       Create a new ftrace instance called "iname".  This instance will appear
32       in /sys/kernel/debug/tracing/instances
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34       The optional buffer-size parameter can be used to control the  size  of
35       the  ftrace  buffers for this instance in the kernel.  A suffix of 'k',
36       'K', 'm', 'M', 'g' or 'G' may be used to specify  kilobytes,  megabytes
37       or gigabytes.
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39       modprobe module-name
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41       Force  the  named  module to be loaded by fdr.  This can be useful when
42       the module is normally loaded on demand and the probes  cannot  be  en‐
43       abled until the module is loaded.
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45       enable subsystem-name/probe-name [filter]
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47       Enable  an ftrace probe in the specified subsystem.  Both the subsystem
48       name and probe name are defined by the kernel.
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50       The optional filter parameter allows an ftrace  filter  to  be  set  as
51       well.  This will limit the amount of data being emitted.  The syntax of
52       the filter language is defined by ftrace itself and the parameters  are
53       defined by the static tracepoint being enabled in the kernel.
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55       enable subsystem-name/all
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57       Enable all ftrace probes for the subsystem.
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59       disable subsystem-name/probe-name
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61       Disable an ftrace probe in the specified subsystem.  This can be useful
62       to disable selective probes when the "ALL" keyword has been used.
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64       disable subsystem-name/all
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66       Disable all probes in the specified subsystem.
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68       saveto file-name [maxsize]
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70       Save the output of enabled probes to the named file.  If  the  optional
71       maxsize  parameter  is  given, the daemon will initiate a log rotation,
72       see Log Rotation below.  A suffix of 'k', 'K', 'm', 'M', 'g' or 'G' may
73       be used to specify kilobytes, megabytes or gigabytes.
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75       If  no  saveto  directive is present, then fdr will create the instance
76       and enable the probes.  In this case, the data can be  harvested  manu‐
77       ally by reading:
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79       /sys/kernel/debug/tracing/instances/iname/trace_pipe
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81       The  ftrace  buffers in the kernel are circular. If no process harvests
82       the data, new data will overwrite old data.
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84       minfree value
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86       Limit the output by the daemon based on free space in the  file  system
87       for  the  save  file.   If free space percentage is below the specified
88       value, no output will be written.
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90       If no minfree directive is present, fdr will use 5% by default.
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LOG ROTATION

93       fdr can use logrotate(8) to manage the output  files.   By  convention,
94       /etc/logrotate.d/instance-name controls the behavior of logrotate.
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96       fdr  will  also  invoke logrotate directly at startup and when reaching
97       the maxsize limit for the save file.
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SEE ALSO

100       https://lwn.net/Articles/410200/
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102       https://www.kernel.org/doc/Documentation/trace/ftrace.txt
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AUTHOR

105       Bill Baker and Calum Mackay
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109                                 15 June 2021                          fdrd(8)
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