a9af6be5bc
The -p (--pid) option enables to trace existing process by its pid.
Committer notes:
Testing it:
Using the function_graph tracer on a process that is just waiting for user
input and thus will make 'perf ftrace' sit there waiting for that, then press
any key on that mutt session and see what happens:
# perf ftrace -t function_graph -p `pidof mutt` | head -40
2) 1.038 us | switch_mm_irqs_off();
------------------------------------------
2) <idle>-0 => mutt-3595
------------------------------------------
2) | finish_task_switch() {
2) | smp_irq_work_interrupt() {
2) | irq_enter() {
2) 0.180 us | rcu_irq_enter();
2) 1.248 us | }
2) | __wake_up() {
2) 0.126 us | _raw_spin_lock_irqsave();
2) | __wake_up_common() {
2) | pollwake() {
2) | default_wake_function() {
2) | try_to_wake_up() {
2) 0.662 us | _raw_spin_lock_irqsave();
2) | select_task_rq_fair() {
2) 1.719 us | effective_load.isra.41();
2) 1.343 us | effective_load.isra.41();
2) | select_idle_sibling() {
2) 0.331 us | idle_cpu();
2) 1.458 us | }
2) 8.350 us | }
2) 0.200 us | _raw_spin_lock();
2) | ttwu_do_activate() {
2) | activate_task() {
2) 0.136 us | update_rq_clock.part.77();
2) | enqueue_task_fair() {
2) | enqueue_entity() {
2) 0.146 us | update_curr();
2) 0.330 us | account_entity_enqueue();
2) 0.280 us | update_cfs_shares();
2) 0.321 us | place_entity();
2) 0.206 us | __enqueue_entity();
2) 6.926 us | }
2) | enqueue_entity() {
2) 0.105 us | update_curr();
2) 0.175 us | account_entity_enqueue();
2) 0.531 us | update_cfs_shares();
#
Signed-off-by: Namhyung Kim <namhyung@kernel.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Cc: Steven Rostedt <rostedt@goodmis.org>
Cc: kernel-team@lge.com
Link: http://lkml.kernel.org/r/20170224011251.14946-1-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
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README
Linux kernel ============ This file was moved to Documentation/admin-guide/README.rst Please notice that there are several guides for kernel developers and users. These guides can be rendered in a number of formats, like HTML and PDF. In order to build the documentation, use ``make htmldocs`` or ``make pdfdocs``. There are various text files in the Documentation/ subdirectory, several of them using the Restructured Text markup notation. See Documentation/00-INDEX for a list of what is contained in each file. Please read the Documentation/process/changes.rst file, as it contains the requirements for building and running the kernel, and information about the problems which may result by upgrading your kernel.