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authorNamhyung Kim <namhyung@kernel.org>2022-03-21 16:46:09 -0700
committerArnaldo Carvalho de Melo <acme@redhat.com>2022-03-22 17:45:39 -0300
commitfeff08395b2c427caadf00f8c22920cfb3306739 (patch)
tree3dcd3d9e0f8ac90594ac05a2982d9b093cc002c8 /tools/perf
parent84005bb6148618cc8429d4011354f4a2f8a02914 (diff)
downloadlinux-feff08395b2c427caadf00f8c22920cfb3306739.tar.bz2
perf ftrace latency: Update documentation
Add description of 'perf ftrace latency' subcommand. Signed-off-by: Namhyung Kim <namhyung@kernel.org> Cc: Andi Kleen <ak@linux.intel.com> Cc: Changbin Du <changbin.du@gmail.com> Cc: Ian Rogers <irogers@google.com> Cc: Ingo Molnar <mingo@kernel.org> Cc: Jiri Olsa <jolsa@kernel.org> Cc: Peter Zijlstra <peterz@infradead.org> Cc: Stephane Eranian <eranian@google.com> Link: https://lore.kernel.org/r/20220321234609.90455-2-namhyung@kernel.org Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Diffstat (limited to 'tools/perf')
-rw-r--r--tools/perf/Documentation/perf-ftrace.txt75
1 files changed, 52 insertions, 23 deletions
diff --git a/tools/perf/Documentation/perf-ftrace.txt b/tools/perf/Documentation/perf-ftrace.txt
index 6e82b7cc0bf0..df4595563801 100644
--- a/tools/perf/Documentation/perf-ftrace.txt
+++ b/tools/perf/Documentation/perf-ftrace.txt
@@ -9,32 +9,24 @@ perf-ftrace - simple wrapper for kernel's ftrace functionality
SYNOPSIS
--------
[verse]
-'perf ftrace' <command>
+'perf ftrace' {trace|latency} <command>
DESCRIPTION
-----------
-The 'perf ftrace' command is a simple wrapper of kernel's ftrace
-functionality. It only supports single thread tracing currently and
-just reads trace_pipe in text and then write it to stdout.
+The 'perf ftrace' command provides a collection of subcommands which use
+kernel's ftrace infrastructure.
-The following options apply to perf ftrace.
+ 'perf ftrace trace' is a simple wrapper of the ftrace. It only supports
+ single thread tracing currently and just reads trace_pipe in text and then
+ write it to stdout.
-OPTIONS
--------
+ 'perf ftrace latency' calculates execution latency of a given function
+ (optionally with BPF) and display it as a histogram.
--t::
---tracer=::
- Tracer to use when neither -G nor -F option is not
- specified: function_graph or function.
+The following options apply to perf ftrace.
--v::
---verbose::
- Increase the verbosity level.
-
--F::
---funcs::
- List available functions to trace. It accepts a pattern to
- only list interested functions.
+COMMON OPTIONS
+--------------
-p::
--pid=::
@@ -43,10 +35,6 @@ OPTIONS
--tid=::
Trace on existing thread id (comma separated list).
--D::
---delay::
- Time (ms) to wait before starting tracing after program start.
-
-a::
--all-cpus::
Force system-wide collection. Scripts run without a <command>
@@ -61,6 +49,28 @@ OPTIONS
Ranges of CPUs are specified with -: 0-2.
Default is to trace on all online CPUs.
+-v::
+--verbose::
+ Increase the verbosity level.
+
+
+OPTIONS for 'perf ftrace trace'
+-------------------------------
+
+-t::
+--tracer=::
+ Tracer to use when neither -G nor -F option is not
+ specified: function_graph or function.
+
+-F::
+--funcs::
+ List available functions to trace. It accepts a pattern to
+ only list interested functions.
+
+-D::
+--delay::
+ Time (ms) to wait before starting tracing after program start.
+
-m::
--buffer-size::
Set the size of per-cpu tracing buffer, <size> is expected to
@@ -114,6 +124,25 @@ OPTIONS
thresh=<n> - Setup trace duration threshold in microseconds.
depth=<n> - Set max depth for function graph tracer to follow.
+
+OPTIONS for 'perf ftrace latency'
+---------------------------------
+
+-T::
+--trace-funcs=::
+ Set the function name to get the histogram. Unlike perf ftrace trace,
+ it only allows single function to calculate the histogram.
+
+-b::
+--use-bpf::
+ Use BPF to measure function latency instead of using the ftrace (it
+ uses function_graph tracer internally).
+
+-n::
+--use-nsec::
+ Use nano-second instead of micro-second as a base unit of the histogram.
+
+
SEE ALSO
--------
linkperf:perf-record[1], linkperf:perf-trace[1]