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Subject[PATCH 13/17] perf tools: Add document for perf-ftrace command
From: Namhyung Kim <>

Cc: Steven Rostedt <>
Cc: Frederic Weisbecker <>
Signed-off-by: Namhyung Kim <>
tools/perf/Documentation/perf-ftrace.txt | 116 +++++++++++++++++++++++++++++++
1 file changed, 116 insertions(+)
create mode 100644 tools/perf/Documentation/perf-ftrace.txt

diff --git a/tools/perf/Documentation/perf-ftrace.txt b/tools/perf/Documentation/perf-ftrace.txt
new file mode 100644
index 000000000000..4463a33e367a
--- /dev/null
+++ b/tools/perf/Documentation/perf-ftrace.txt
@@ -0,0 +1,116 @@
+perf-ftrace - A front end for kernel's ftrace
+'perf ftrace' {live|record} [<options>] [<command>]
+'perf ftrace' {show|report} [<options>]
+This command reads the ftrace buffer and displays the trace recorded.
+There are several variants of perf ftrace:
+ 'perf ftrace live <command>' to see a live trace of kernel functions
+ via trace_pipe during executing the <command>. If <command> is not
+ specified, one of the target options (-p, -a or -C) should be given.
+ It just prints out the result to stdout and doesn't save any files.
+ 'perf ftrace record <command>' to record trace entries of kernel
+ functions during the execution of the <command>. Like 'perf ftrace
+ live', at least one of <command> and/or target options should be
+ given in order to start recording. The recorded results are saved
+ under a directory ('' by default) and will be used by
+ other perf-ftrace tools like 'show' and 'report'.
+ 'perf ftrace show' to see the trace of recorded functions. It shows
+ functions sorted by time so the end result might be interspersed if
+ there's a concurrent execution.
+ 'perf ftrace report' to display the result in an usual perf-report
+ style - entries are sorted by given sort keys and output is resorted
+ by its overhead.
+ Any command you can specify in a shell.
+ The ftrace tracer to be used (default: function_graph).
+ Currently, only 'function' and 'function_graph' are supported
+ by 'record' command. 'live' command accepts any available
+ tracer in system and outputs trace result directly from the
+ ftrace's trace_pipe.
+ Record events on existing process ID (comma separated list).
+ Used by 'live' and 'record' subcommands only.
+ Force system-wide collection. Scripts run without a <command>
+ normally use -a by default, while scripts run with a <command>
+ normally don't - this option allows the latter to be run in
+ system-wide mode. Used by 'live' and 'record' subcommands only.
+--cpu:: Only process samples for the list of CPUs provided.
+ Multiple CPUs can be provided as a comma-separated list with
+ no space: 0,1. Ranges of CPUs are specified with -: 0-2.
+ Default is to report samples on all online CPUs.
+ Sort histogram entries by given key(s) - multiple keys can be
+ specified in CSV format. Following sort keys are available:
+ pid, comm, dso, symbol, cpu.
+ Each key has following meaning:
+ - comm: command (name) of the task
+ - pid: command and tid of the task
+ - dso: name of library or module executed at the time of sample
+ - symbol: name of function executed at the time of sample
+ - cpu: cpu number the task ran at the time of sample
+ By default, comm, dso and symbol keys are used.
+ (i.e. --sort comm,dso,symbol)
+ Used by 'report' subcommands only.
+ Input directory name excluding '.dir' at the end.
+ (default:
+ Output directory name excluding '.dir' at the end.
+ (default:
+ Be more verbose (show counter open errors, etc).
+ Dump raw trace in ASCII. Used by 'report' subcommands only.
+ Display extended information about the record. This adds
+ information which may be very large and thus may clutter the
+ display. It currently includes: cpu and numa topology of the
+ host system. It can only be used with the 'report' subcommand.
+linkperf:perf-record[1], linkperf:perf-report[1],

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