trace-cmd-restore - Man Page

trace-cmd restore [Options] [command] cpu-file [cpu-file ​...]

The trace-cmd(1) restore command will restore a crashed trace-cmd-record(1) file​. If for some reason a trace-cmd record fails, it will leave a the per-cpu data files and not create the final trace​.dat file​. The trace-cmd restore will append the files to create a working trace​.dat file that can be read with trace-cmd-report(1)​.

When trace-cmd record runs, it spawns off a process per CPU and writes to a per cpu file usually called trace​.dat​.cpuX, where X represents the CPU number that it is tracing​. If the -o option was used in the trace-cmd record, then the CPU data files will have that name instead of the trace​.dat name​. If a unexpected crash occurs before the tracing is finished, then the per CPU files will still exist but there will not be any trace​.dat file to read from​. trace-cmd restore will allow you to create a trace​.dat file with the existing data files​.

-c

Create a partial trace​.dat file from the machine, to be used with a full trace-cmd restore at another time​. This option is useful for embedded devices​. If a server contains the cpu files of a crashed trace-cmd record (or trace-cmd listen), trace-cmd restore can be executed on the embedded device with the -c option to get all the stored information of that embedded device​. Then the file created could be copied to the server to run the trace-cmd restore there with the cpu files​.

If *-o* is not specified, then the file created will be called
'trace-partial​.dat'​. This is because the file is not a full version
of something that trace-cmd-report(1) could use​.

-t tracing_dir

Used with -c, it overrides the location to read the events from​. By default, tracing information is read from the debugfs/tracing directory​. -t will use that location instead​. This can be useful if the trace​.dat file to create is from another machine​. Just tar -cvf events​.tar debugfs/tracing and copy and untar that file locally, and use that directory instead​.

-k kallsyms

Used with -c, it overrides where to read the kallsyms file from​. By default, /proc/kallsyms is used​. -k will override the file to read the kallsyms from​. This can be useful if the trace​.dat file to create is from another machine​. Just copy the /proc/kallsyms file locally, and use -k to point to that file​.

-o output'

By default, trace-cmd restore will create a trace​.dat file (or trace-partial​.dat if -c is specified)​. You can specify a different file to write to with the -o option​.

-i input

By default, trace-cmd restore will read the information of the current system to create the initial data stored in the trace​.dat file​. If the crash was on another machine, then that machine should have the trace-cmd restore run with the -c option to create the trace​.dat partial file​. Then that file can be copied to the current machine where trace-cmd restore will use -i to load that file instead of reading from the current system​.

If a crash happened on another box, you could run:

$ trace-cmd restore -c -o box-partial​.dat

Then on the server that has the cpu files:

$ trace-cmd restore -i box-partial​.dat trace​.dat​.cpu0 trace​.dat​.cpu1

This would create a trace​.dat file for the embedded box​.

trace-cmd(1), trace-cmd-record(1), trace-cmd-report(1), trace-cmd-start(1), trace-cmd-stop(1), trace-cmd-extract(1), trace-cmd-reset(1), trace-cmd-split(1), trace-cmd-list(1), trace-cmd-listen(1)

Written by Steven Rostedt, <rostedt@goodmis​.org​^[1]>

https://git​.kernel​.org/pub/scm/utils/trace-cmd/trace-cmd​.git/

Copyright (C) 2010 Red Hat, Inc​. Free use of this software is granted under the terms of the GNU Public License (GPL)​.

1.

rostedt@goodmis.org
mailto:rostedt@goodmis.org

trace-cmd(1).