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
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.
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.
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.
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.
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.
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.
This page is part of the trace-cmd (a front-end for Ftrace) project.
Information about the project can be found at [unknown -- if you
know, please contact firstname.lastname@example.org] If you have a bug report for
this manual page, send it to Steven Rostedt <email@example.com>.
This page was obtained from the project's upstream Git repository
on 2017-03-13. If you discover any rendering problems in this HTML
version of the page, or you believe there is a better or more up-to-
date source for the page, or you have corrections or improvements to
the information in this COLOPHON (which is not part of the original
manual page), send a mail to firstname.lastname@example.org