[tip:perf/core] perf stat: Create events as disabled

[tip-bot for Jiri Olsa]

Commit-ID:  67ccdecd09cac818146b1e153ff901cb67570012
Gitweb:     http://git.kernel.org/tip/67ccdecd09cac818146b1e153ff901cb67570012
Author:     Jiri Olsa <jolsa@xxxxxxxxxx>
AuthorDate: Thu, 3 Dec 2015 10:06:44 +0100
Committer:  Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
CommitDate: Mon, 7 Dec 2015 18:12:59 -0300

perf stat: Create events as disabled

Currently we have 2 kinds of stat counters based on when the event is
enabled:

  1) tracee command events, which are enable once the
     tracee executes exec syscall (enable_on_exec bit)
  2) all other events which get alive within the
     perf_event_open syscall

And 2) case could raise a problem in case we want additional filter to
be attached for event. In this case we want the event to be enabled
after it's configured with filter.

Changing the behaviour of 2) events, so they all are created as disabled
(disabled bit). Adding extra enable call to make them alive once they
finish setup.

Signed-off-by: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: Adrian Hunter <adrian.hunter@xxxxxxxxx>
Cc: David Ahern <dsahern@xxxxxxxxx>
Cc: Namhyung Kim <namhyung@xxxxxxxxxx>
Cc: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Link: http://lkml.kernel.org/r/1449133606-14429-6-git-send-email-jolsa@xxxxxxxxxx
Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
---
 tools/perf/builtin-stat.c | 25 +++++++++++++++++++------
 1 file changed, 19 insertions(+), 6 deletions(-)

diff --git a/tools/perf/builtin-stat.c b/tools/perf/builtin-stat.c
index 8ca40de..2e70610 100644
--- a/tools/perf/builtin-stat.c
+++ b/tools/perf/builtin-stat.c
@@ -168,11 +168,18 @@ static int create_perf_stat_counter(struct perf_evsel *evsel)
 	attr->sample_period = 0;
 	attr->sample_type   = 0;
 
+	/*
+	 * Disabling all counters initially, they will be enabled
+	 * either manually by us or by kernel via enable_on_exec
+	 * set later.
+	 */
+	if (perf_evsel__is_group_leader(evsel))
+		attr->disabled = 1;
+
 	if (target__has_cpu(&target))
 		return perf_evsel__open_per_cpu(evsel, perf_evsel__cpus(evsel));
 
 	if (!target__has_task(&target) && perf_evsel__is_group_leader(evsel)) {
-		attr->disabled = 1;
 		if (!initial_delay)
 			attr->enable_on_exec = 1;
 	}
@@ -251,12 +258,18 @@ static void process_interval(void)
 	print_counters(&rs, 0, NULL);
 }
 
-static void handle_initial_delay(void)
+static void enable_counters(void)
 {
-	if (initial_delay) {
+	if (initial_delay)
 		usleep(initial_delay * 1000);
+
+	/*
+	 * We need to enable counters only if:
+	 * - we don't have tracee (attaching to task or cpu)
+	 * - we have initial delay configured
+	 */
+	if (!target__none(&target) || initial_delay)
 		perf_evlist__enable(evsel_list);
-	}
 }
 
 static volatile int workload_exec_errno;
@@ -353,7 +366,7 @@ static int __run_perf_stat(int argc, const char **argv)
 
 	if (forks) {
 		perf_evlist__start_workload(evsel_list);
-		handle_initial_delay();
+		enable_counters();
 
 		if (interval) {
 			while (!waitpid(child_pid, &status, WNOHANG)) {
@@ -372,7 +385,7 @@ static int __run_perf_stat(int argc, const char **argv)
 		if (WIFSIGNALED(status))
 			psignal(WTERMSIG(status), argv[0]);
 	} else {
-		handle_initial_delay();
+		enable_counters();
 		while (!done) {
 			nanosleep(&ts, NULL);
 			if (interval)
--
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