perf script: Allow specifying event to switch off processing of other events

Counterpart of --switch-on:

  # perf record -e sched:*,syscalls:sys_*_nanosleep sleep 1
  [ perf record: Woken up 36 times to write data ]
  [ perf record: Captured and wrote 0.032 MB perf.data (10 samples) ]
  #
  # perf script
      :20918 20918 [002] 109866.143696:            sched:sched_waking: comm=perf pid=20919 prio=120 target_cpu=001
      :20918 20918 [002] 109866.143702:            sched:sched_wakeup: perf:20919 [120] success=1 CPU:001
       sleep 20919 [001] 109866.144081:      sched:sched_process_exec: filename=/usr/bin/sleep pid=20919 old_pid=20919
       sleep 20919 [001] 109866.144408:  syscalls:sys_enter_nanosleep: rqtp: 0x7ffc2384fef0, rmtp: 0x00000000
       sleep 20919 [001] 109866.144411:      sched:sched_stat_runtime: comm=sleep pid=20919 runtime=521249 [ns] vruntime=202919398131 [n>
       sleep 20919 [001] 109866.144412:            sched:sched_switch: sleep:20919 [120] S ==> swapper/1:0 [120]
     swapper     0 [001] 109867.144568:            sched:sched_waking: comm=sleep pid=20919 prio=120 target_cpu=001
     swapper     0 [001] 109867.144586:            sched:sched_wakeup: sleep:20919 [120] success=1 CPU:001
       sleep 20919 [001] 109867.144614:   syscalls:sys_exit_nanosleep: 0x0
       sleep 20919 [001] 109867.144753:      sched:sched_process_exit: comm=sleep pid=20919 prio=120
  #
  # perf script --switch-off syscalls:sys_exit_nanosleep
      :20918 20918 [002] 109866.143696:            sched:sched_waking: comm=perf pid=20919 prio=120 target_cpu=001
      :20918 20918 [002] 109866.143702:            sched:sched_wakeup: perf:20919 [120] success=1 CPU:001
       sleep 20919 [001] 109866.144081:      sched:sched_process_exec: filename=/usr/bin/sleep pid=20919 old_pid=20919
       sleep 20919 [001] 109866.144408:  syscalls:sys_enter_nanosleep: rqtp: 0x7ffc2384fef0, rmtp: 0x00000000
       sleep 20919 [001] 109866.144411:      sched:sched_stat_runtime: comm=sleep pid=20919 runtime=521249 [ns] vruntime=202919398131 [n>
       sleep 20919 [001] 109866.144412:            sched:sched_switch: sleep:20919 [120] S ==> swapper/1:0 [120]
     swapper     0 [001] 109867.144568:            sched:sched_waking: comm=sleep pid=20919 prio=120 target_cpu=001
     swapper     0 [001] 109867.144586:            sched:sched_wakeup: sleep:20919 [120] success=1 CPU:001
       sleep 20919 [001] 109867.144753:      sched:sched_process_exit: comm=sleep pid=20919 prio=120
  #
  # perf script --switch-on syscalls:sys_enter_nanosleep --switch-off syscalls:sys_exit_nanosleep
       sleep 20919 [001] 109866.144411:      sched:sched_stat_runtime: comm=sleep pid=20919 runtime=521249 [ns] vruntime=202919398131 [n>
       sleep 20919 [001] 109866.144412:            sched:sched_switch: sleep:20919 [120] S ==> swapper/1:0 [120]
     swapper     0 [001] 109867.144568:            sched:sched_waking: comm=sleep pid=20919 prio=120 target_cpu=001
     swapper     0 [001] 109867.144586:            sched:sched_wakeup: sleep:20919 [120] success=1 CPU:001
  #
  # perf script --switch-on syscalls:sys_enter_nanosleep --switch-off syscalls:sys_exit_nanosleep --show-on-off
       sleep 20919 [001] 109866.144408:  syscalls:sys_enter_nanosleep: rqtp: 0x7ffc2384fef0, rmtp: 0x00000000
       sleep 20919 [001] 109866.144411:      sched:sched_stat_runtime: comm=sleep pid=20919 runtime=521249 [ns] vruntime=202919398131 [n>
       sleep 20919 [001] 109866.144412:            sched:sched_switch: sleep:20919 [120] S ==> swapper/1:0 [120]
     swapper     0 [001] 109867.144568:            sched:sched_waking: comm=sleep pid=20919 prio=120 target_cpu=001
     swapper     0 [001] 109867.144586:            sched:sched_wakeup: sleep:20919 [120] success=1 CPU:001
       sleep 20919 [001] 109867.144614:   syscalls:sys_exit_nanosleep: 0x0
  #

Now think about using this together with 'perf probe' to create custom on/off
events in your app :-)

Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Florian Weimer <fweimer@redhat.com>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: William Cohen <wcohen@redhat.com>
Link: https://lkml.kernel.org/n/tip-li3j01c4tmj9kw6ydsl8swej@git.kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

2 files changed, 32 insertions, 4 deletions

diff --git a/tools/perf/Documentation/perf-script.txt b/tools/perf/Documentation/perf-script.txt
index 24eea68ee829..2599b057e47b 100644
--- a/tools/perf/Documentation/perf-script.txt
+++ b/tools/perf/Documentation/perf-script.txt
@@ -420,8 +420,11 @@ include::itrace.txt[]
 --switch-on EVENT_NAME::
         Only consider events after this event is found.
 
+--switch-off EVENT_NAME::
+        Stop considering events after this event is found.
+
 --show-on-off-events::
-        Show the --switch-on event too.
+        Show the --switch-on/off events too.
 
 SEE ALSO
 --------
diff --git a/tools/perf/builtin-script.c b/tools/perf/builtin-script.c
index fa0cc8b0eccc..b6eed0f7e835 100644
--- a/tools/perf/builtin-script.c
+++ b/tools/perf/builtin-script.c
@@ -1617,7 +1617,8 @@ static int perf_sample__fprintf_synth(struct perf_sample *sample,
 }
 
 struct evswitch {
-        struct evsel *on;
+        struct evsel *on,
+                     *off;
         bool         discarding;
         bool         show_on_off_events;
 };
@@ -1820,8 +1821,20 @@ static void process_event(struct perf_script *script,
 
                 if (!script->evswitch.show_on_off_events)
                         return;
+
+                goto print_it;
         }
 
+        if (script->evswitch.off && !script->evswitch.discarding) {
+                if (script->evswitch.off != evsel)
+                        goto print_it;
+
+                script->evswitch.discarding = true;
+
+                if (!script->evswitch.show_on_off_events)
+                        return;
+        }
+print_it:
         ++es->samples;
 
         perf_sample__fprintf_start(sample, thread, evsel,
@@ -3412,7 +3425,8 @@ int cmd_script(int argc, const char **argv)
         struct utsname uts;
         char *script_path = NULL;
         const char **__argv;
-        const char *event_switch_on = NULL;
+        const char *event_switch_on  = NULL,
+                   *event_switch_off = NULL;
         int i, j, err = 0;
         struct perf_script script = {
                 .tool = {
@@ -3557,7 +3571,9 @@ int cmd_script(int argc, const char **argv)
         OPT_STRING(0, "guestmodules", &symbol_conf.default_guest_modules,
                    "file", "file saving guest os /proc/modules"),
         OPT_STRING(0, "switch-on", &event_switch_on,
-                   "event", "Consider events from the first ocurrence of this event"),
+                   "event", "Consider events after the ocurrence of this event"),
+        OPT_STRING(0, "switch-off", &event_switch_off,
+                   "event", "Stop considering events after the ocurrence of this event"),
         OPT_BOOLEAN(0, "show-on-off-events", &script.evswitch.show_on_off_events,
                     "Show the on/off switch events, used with --switch-on"),
         OPT_END()
@@ -3894,6 +3910,15 @@ int cmd_script(int argc, const char **argv)
                 script.evswitch.discarding = true;
         }
 
+        if (event_switch_off) {
+                script.evswitch.off = perf_evlist__find_evsel_by_str(session->evlist, event_switch_off);
+                if (script.evswitch.off == NULL) {
+                        fprintf(stderr, "switch-off event not found (%s)\n", event_switch_off);
+                        err = -ENOENT;
+                        goto out_delete;
+                }
+        }
+
         err = __cmd_script(&script);
 
         flush_scripting();