trace-cmd-show(1) — Linux manual page

TRACE-CMD-SHOW(1)           libtracefs Manual          TRACE-CMD-SHOW(1)

NAME         top

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

SYNOPSIS         top

       trace-cmd show [OPTIONS]

DESCRIPTION         top

       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

OPTIONS         top

       -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.

       --buffer_subbuf_size
           Show the size in kilobytes of the sub-buffers of the ring
           buffer. The ring buffer is broken up into equal size
           sub-buffers were an event can only be as big as the
           sub-buffer data section (the size minus its meta data).

       --buffer_percent
           Show the percentage the buffer must be filled before a reader
           that is blocked on the trace_pipe_raw file will be woken up.

               0       : wake up immediately on any new data
               1 - 99  : wake up on this percentage of the sub-buffers being full
               100     : wake up after the buffer is full and the writer is on the last sub-buffer

       --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.

       --hist [system:]event
           Show the content of a histogram "hist" file for a given event

       --trigger [system:]event
           Show the content of the "trigger" file for a given event

       --cpumask
           Show the mask of CPUs that tracing will trace.

SEE ALSO         top

       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)

AUTHOR         top

       Written by Steven Rostedt, <[email protected][1]>

RESOURCES         top

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

COPYING         top

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

NOTES         top

        1. [email protected]
           mailto:[email protected]

COLOPHON         top

       This page is part of the trace-cmd (a front-end for Ftrace)
       project.  Information about the project can be found at 
       ⟨https://www.trace-cmd.org/⟩.  If you have a bug report for this
       manual page, see ⟨https://www.trace-cmd.org/⟩.  This page was
       obtained from the project's upstream Git repository
       ⟨https://git.kernel.org/pub/scm/utils/trace-cmd/trace-cmd.git⟩ on
       2024-06-14.  (At that time, the date of the most recent commit
       that was found in the repository was 2024-02-22.)  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 [email protected]

libtracefs                     06/13/2024              TRACE-CMD-SHOW(1)

HTML rendering created 2024-06-26 by Michael Kerrisk, author of The Linux Programming Interface. For details of in-depth Linux/UNIX system programming training courses that I teach, look here. Hosting by jambit GmbH.