[PATCH 04/17] perf script: Allow specifying event to switch off processing of other events

Arnaldo Carvalho de Melo
2019-08-16T20:18:11Z

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>
---
tools/perf/Documentation/perf-script.txt | 5 +++-
tools/perf/builtin-script.c | 31 +++++++++++++++++++++---
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();
--
2.21.0