DOKK / manpages / debian 11 / trace-cmd / trace-cmd-show.1.en
TRACE-CMD-SHOW(1)   TRACE-CMD-SHOW(1)

trace-cmd-show - show the contents of the Ftrace Linux kernel tracing buffer.

trace-cmd show [OPTIONS]

The trace-cmd(1) show displays the contents of one of the Ftrace Linux kernel tracing files: trace, snapshot, or trace_pipe. It is basically the equivalent of doing:

cat /sys/kernel/debug/tracing/trace

-p

Instead of displaying the contents of the "trace" file, use the "trace_pipe" file. The difference between the two is that the "trace" file is static. That is, if tracing is stopped, the "trace" file will show the same contents each time. 

The "trace_pipe" file is a consuming read, where a read of the file
will consume the output of what was read and it will not read the
same thing a second time even if tracing is stopped. This file
als will block. If no data is available, trace-cmd show will stop
and wait for data to appear.

-s

Instead of reading the "trace" file, read the snapshot file. The snapshot is made by an application writing into it and the kernel will perform as swap between the currently active buffer and the current snapshot buffer. If no more swaps are made, the snapshot will remain static. This is not a consuming read.

-c cpu

Read only the trace file for a specified CPU.

-f

Display the full path name of the file that is being displayed.

-B buf

If a buffer instance was created, then the -B option will access the files associated with the given buffer.

--tracing_on

Show if tracing is on for the given instance.

--current_tracer

Show what the current tracer is.

--buffer_size

Show the current buffer size (per-cpu)

--buffer_total_size

Show the total size of all buffers.

--ftrace_filter

Show what function filters are set.

--ftrace_notrace

Show what function disabled filters are set.

--ftrace_pid

Show the PIDs the function tracer is limited to (if any).

--graph_function

Show the functions that will be graphed.

--graph_notrace

Show the functions that will not be graphed.

--cpumask

Show the mask of CPUs that tracing will trace.

trace-cmd(1), trace-cmd-record(1), trace-cmd-report(1), trace-cmd-start(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]>

git://git.kernel.org/pub/scm/linux/kernel/git/rostedt/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
08/19/2020