diff options
Diffstat (limited to 'tools/perf/lib/Documentation/tutorial')
-rw-r--r-- | tools/perf/lib/Documentation/tutorial/tutorial.rst | 123 |
1 files changed, 123 insertions, 0 deletions
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 |