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Subject[tip:perf/core] libperf: Initial documentation
Commit-ID:  f4f48e9c1adb49f732ac0abc4b2513f2b62a10cb
Gitweb: https://git.kernel.org/tip/f4f48e9c1adb49f732ac0abc4b2513f2b62a10cb
Author: Jiri Olsa <jolsa@kernel.org>
AuthorDate: Sun, 21 Jul 2019 13:25:06 +0200
Committer: Arnaldo Carvalho de Melo <acme@redhat.com>
CommitDate: Mon, 29 Jul 2019 18:34:47 -0300

libperf: Initial documentation

Add initial drafts of documentation files, hugely unfinished.

Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Alexey Budankov <alexey.budankov@linux.intel.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Michael Petlan <mpetlan@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20190721112506.12306-80-jolsa@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
tools/perf/lib/Documentation/Makefile | 7 ++
tools/perf/lib/Documentation/man/libperf.rst | 100 +++++++++++++++++
tools/perf/lib/Documentation/tutorial/tutorial.rst | 123 +++++++++++++++++++++
3 files changed, 230 insertions(+)

diff --git a/tools/perf/lib/Documentation/Makefile b/tools/perf/lib/Documentation/Makefile
new file mode 100644
index 000000000000..586425a88795
--- /dev/null
+++ b/tools/perf/lib/Documentation/Makefile
@@ -0,0 +1,7 @@
+all:
+ rst2man man/libperf.rst > man/libperf.7
+ rst2pdf tutorial/tutorial.rst
+
+clean:
+ rm -f man/libperf.7
+ rm -f tutorial/tutorial.pdf
diff --git a/tools/perf/lib/Documentation/man/libperf.rst b/tools/perf/lib/Documentation/man/libperf.rst
new file mode 100644
index 000000000000..09a270fccb9c
--- /dev/null
+++ b/tools/perf/lib/Documentation/man/libperf.rst
@@ -0,0 +1,100 @@
+.. SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause)
+
+libperf
+
+The libperf library provides an API to access the linux kernel perf
+events subsystem. It provides the following high level objects:
+
+ - struct perf_cpu_map
+ - struct perf_thread_map
+ - struct perf_evlist
+ - struct perf_evsel
+
+reference
+=========
+Function reference by header files:
+
+perf/core.h
+-----------
+.. code-block:: c
+
+ typedef int (\*libperf_print_fn_t)(enum libperf_print_level level,
+ const char \*, va_list ap);
+
+ void libperf_set_print(libperf_print_fn_t fn);
+
+perf/cpumap.h
+-------------
+.. code-block:: c
+
+ struct perf_cpu_map \*perf_cpu_map__dummy_new(void);
+ struct perf_cpu_map \*perf_cpu_map__new(const char \*cpu_list);
+ struct perf_cpu_map \*perf_cpu_map__read(FILE \*file);
+ struct perf_cpu_map \*perf_cpu_map__get(struct perf_cpu_map \*map);
+ void perf_cpu_map__put(struct perf_cpu_map \*map);
+ int perf_cpu_map__cpu(const struct perf_cpu_map \*cpus, int idx);
+ int perf_cpu_map__nr(const struct perf_cpu_map \*cpus);
+ perf_cpu_map__for_each_cpu(cpu, idx, cpus)
+
+perf/threadmap.h
+----------------
+.. code-block:: c
+
+ struct perf_thread_map \*perf_thread_map__new_dummy(void);
+ void perf_thread_map__set_pid(struct perf_thread_map \*map, int thread, pid_t pid);
+ char \*perf_thread_map__comm(struct perf_thread_map \*map, int thread);
+ struct perf_thread_map \*perf_thread_map__get(struct perf_thread_map \*map);
+ void perf_thread_map__put(struct perf_thread_map \*map);
+
+perf/evlist.h
+-------------
+.. code-block::
+
+ void perf_evlist__init(struct perf_evlist \*evlist);
+ void perf_evlist__add(struct perf_evlist \*evlist,
+ struct perf_evsel \*evsel);
+ void perf_evlist__remove(struct perf_evlist \*evlist,
+ struct perf_evsel \*evsel);
+ struct perf_evlist \*perf_evlist__new(void);
+ void perf_evlist__delete(struct perf_evlist \*evlist);
+ struct perf_evsel\* perf_evlist__next(struct perf_evlist \*evlist,
+ struct perf_evsel \*evsel);
+ int perf_evlist__open(struct perf_evlist \*evlist);
+ void perf_evlist__close(struct perf_evlist \*evlist);
+ void perf_evlist__enable(struct perf_evlist \*evlist);
+ void perf_evlist__disable(struct perf_evlist \*evlist);
+ perf_evlist__for_each_evsel(evlist, pos)
+ void perf_evlist__set_maps(struct perf_evlist \*evlist,
+ struct perf_cpu_map \*cpus,
+ struct perf_thread_map \*threads);
+
+perf/evsel.h
+------------
+.. code-block:: c
+
+ struct perf_counts_values {
+ union {
+ struct {
+ uint64_t val;
+ uint64_t ena;
+ uint64_t run;
+ };
+ uint64_t values[3];
+ };
+ };
+
+ void perf_evsel__init(struct perf_evsel \*evsel,
+ struct perf_event_attr \*attr);
+ struct perf_evsel \*perf_evsel__new(struct perf_event_attr \*attr);
+ void perf_evsel__delete(struct perf_evsel \*evsel);
+ int perf_evsel__open(struct perf_evsel \*evsel, struct perf_cpu_map \*cpus,
+ struct perf_thread_map \*threads);
+ void perf_evsel__close(struct perf_evsel \*evsel);
+ int perf_evsel__read(struct perf_evsel \*evsel, int cpu, int thread,
+ struct perf_counts_values \*count);
+ int perf_evsel__enable(struct perf_evsel \*evsel);
+ int perf_evsel__disable(struct perf_evsel \*evsel);
+ int perf_evsel__apply_filter(struct perf_evsel \*evsel, const char \*filter);
+ struct perf_cpu_map \*perf_evsel__cpus(struct perf_evsel \*evsel);
+ struct perf_thread_map \*perf_evsel__threads(struct perf_evsel \*evsel);
+ struct perf_event_attr \*perf_evsel__attr(struct perf_evsel \*evsel);
diff --git a/tools/perf/lib/Documentation/tutorial/tutorial.rst b/tools/perf/lib/Documentation/tutorial/tutorial.rst
new file mode 100644
index 000000000000..7be7bc27b385
--- /dev/null
+++ b/tools/perf/lib/Documentation/tutorial/tutorial.rst
@@ -0,0 +1,123 @@
+.. SPDX-License-Identifier: (LGPL-2.1 OR BSD-2-Clause)
+
+libperf tutorial
+================
+
+Compile and install libperf from kernel sources
+===============================================
+.. code-block:: bash
+
+ git clone git://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
+ cd linux/tools/perf/lib
+ make
+ sudo make install prefix=/usr
+
+Libperf object
+==============
+The libperf library provides several high level objects:
+
+struct perf_cpu_map
+ Provides a cpu list abstraction.
+
+struct perf_thread_map
+ Provides a thread list abstraction.
+
+struct perf_evsel
+ Provides an abstraction for single a perf event.
+
+struct perf_evlist
+ Gathers several struct perf_evsel object and performs functions on all of them.
+
+The exported API binds these objects together,
+for full reference see the libperf.7 man page.
+
+Examples
+========
+Examples aim to explain libperf functionality on simple use cases.
+They are based in on a checked out linux kernel git tree:
+
+.. code-block:: bash
+
+ $ cd tools/perf/lib/Documentation/tutorial/
+ $ ls -d ex-*
+ ex-1-compile ex-2-evsel-stat ex-3-evlist-stat
+
+ex-1-compile example
+====================
+This example shows the basic usage of *struct perf_cpu_map*,
+how to create it and display its cpus:
+
+.. code-block:: bash
+
+ $ cd ex-1-compile/
+ $ make
+ gcc -o test test.c -lperf
+ $ ./test
+ 0 1 2 3 4 5 6 7
+
+
+The full code listing is here:
+
+.. code-block:: c
+
+ 1 #include <perf/cpumap.h>
+ 2
+ 3 int main(int argc, char **Argv)
+ 4 {
+ 5 struct perf_cpu_map *cpus;
+ 6 int cpu, tmp;
+ 7
+ 8 cpus = perf_cpu_map__new(NULL);
+ 9
+ 10 perf_cpu_map__for_each_cpu(cpu, tmp, cpus)
+ 11 fprintf(stdout, "%d ", cpu);
+ 12
+ 13 fprintf(stdout, "\n");
+ 14
+ 15 perf_cpu_map__put(cpus);
+ 16 return 0;
+ 17 }
+
+
+First you need to include the proper header to have *struct perf_cpumap*
+declaration and functions:
+
+.. code-block:: c
+
+ 1 #include <perf/cpumap.h>
+
+
+The *struct perf_cpumap* object is created by *perf_cpu_map__new* call.
+The *NULL* argument asks it to populate the object with the current online CPUs list:
+
+.. code-block:: c
+
+ 8 cpus = perf_cpu_map__new(NULL);
+
+This is paired with a *perf_cpu_map__put*, that drops its reference at the end, possibly deleting it.
+
+.. code-block:: c
+
+ 15 perf_cpu_map__put(cpus);
+
+The iteration through the *struct perf_cpumap* CPUs is done using the *perf_cpu_map__for_each_cpu*
+macro which requires 3 arguments:
+
+- cpu - the cpu numer
+- tmp - iteration helper variable
+- cpus - the *struct perf_cpumap* object
+
+.. code-block:: c
+
+ 10 perf_cpu_map__for_each_cpu(cpu, tmp, cpus)
+ 11 fprintf(stdout, "%d ", cpu);
+
+ex-2-evsel-stat example
+=======================
+
+TBD
+
+ex-3-evlist-stat example
+========================
+
+TBD
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