[PATCH] perf stat: Poll for monitored tasks being alive

[PATCH] perf stat: Poll for monitored tasks being alive

[Jiri Olsa]

Adding the check for tasks we monitor via -p/-t options,
and finish stat if there's no longer task to monitor.

Cc: Jin Yao <yao.jin@linux.intel.com>
Requested-by: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/n/tip-dfqvnvz0oqu5zg149aquz1jb@git.kernel.org
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
---
 tools/perf/builtin-stat.c | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/tools/perf/builtin-stat.c b/tools/perf/builtin-stat.c
index b86aba1c8028..d1028d7755bb 100644
--- a/tools/perf/builtin-stat.c
+++ b/tools/perf/builtin-stat.c
@@ -409,6 +409,28 @@ static struct perf_evsel *perf_evsel__reset_weak_group(struct perf_evsel *evsel)
 	return leader;
 }
 
+static bool is_target_alive(struct target *_target,
+			    struct thread_map *threads)
+{
+	struct stat st;
+	int i;
+
+	if (!target__has_task(_target))
+		return true;
+
+	for (i = 0; i < threads->nr; i++) {
+		char path[PATH_MAX];
+
+		scnprintf(path, PATH_MAX, "%s/%d", procfs__mountpoint(),
+			  threads->map[i].pid);
+
+		if (!stat(path, &st))
+			return true;
+	}
+
+	return false;
+}
+
 static int __run_perf_stat(int argc, const char **argv, int run_idx)
 {
 	int interval = stat_config.interval;
@@ -579,6 +601,8 @@ static int __run_perf_stat(int argc, const char **argv, int run_idx)
 		enable_counters();
 		while (!done) {
 			nanosleep(&ts, NULL);
+			if (!is_target_alive(&target, evsel_list->threads))
+				break;
 			if (timeout)
 				break;
 			if (interval) {
-- 
2.17.2

Re: [PATCH] perf stat: Poll for monitored tasks being alive

[Arnaldo Carvalho de Melo]

Em Mon, Oct 22, 2018 at 11:30:15AM +0200, Jiri Olsa escreveu:
> Adding the check for tasks we monitor via -p/-t options,
> and finish stat if there's no longer task to monitor.

Wonder if instead of doing all those scnprintf, etc, we couldn't have a
perf ring buffer with a dummy event and then ask for PERF_RECORD_EXIT on
it, poll it, etc.

Thought about using getpgid(pid) but thagt also involves radix tree
lookups, so should also be more expensive than asking the kernel perf to
tell us about the exits.

Anyway, that can be done on top, if someone is interested, applying.

- Arnaldo
 
> Cc: Jin Yao <yao.jin@linux.intel.com>
> Requested-by: Stephane Eranian <eranian@google.com>
> Link: http://lkml.kernel.org/n/tip-dfqvnvz0oqu5zg149aquz1jb@git.kernel.org
> Signed-off-by: Jiri Olsa <jolsa@kernel.org>
> ---
>  tools/perf/builtin-stat.c | 24 ++++++++++++++++++++++++
>  1 file changed, 24 insertions(+)
> 
> diff --git a/tools/perf/builtin-stat.c b/tools/perf/builtin-stat.c
> index b86aba1c8028..d1028d7755bb 100644
> --- a/tools/perf/builtin-stat.c
> +++ b/tools/perf/builtin-stat.c
> @@ -409,6 +409,28 @@ static struct perf_evsel *perf_evsel__reset_weak_group(struct perf_evsel *evsel)
>  	return leader;
>  }
>  
> +static bool is_target_alive(struct target *_target,
> +			    struct thread_map *threads)
> +{
> +	struct stat st;
> +	int i;
> +
> +	if (!target__has_task(_target))
> +		return true;
> +
> +	for (i = 0; i < threads->nr; i++) {
> +		char path[PATH_MAX];
> +
> +		scnprintf(path, PATH_MAX, "%s/%d", procfs__mountpoint(),
> +			  threads->map[i].pid);
> +
> +		if (!stat(path, &st))
> +			return true;
> +	}
> +
> +	return false;
> +}
> +
>  static int __run_perf_stat(int argc, const char **argv, int run_idx)
>  {
>  	int interval = stat_config.interval;
> @@ -579,6 +601,8 @@ static int __run_perf_stat(int argc, const char **argv, int run_idx)
>  		enable_counters();
>  		while (!done) {
>  			nanosleep(&ts, NULL);
> +			if (!is_target_alive(&target, evsel_list->threads))
> +				break;
>  			if (timeout)
>  				break;
>  			if (interval) {
> -- 
> 2.17.2

[tip:perf/urgent] perf stat: Poll for monitored tasks being alive

[tip-bot for Jiri Olsa]

Commit-ID:  cbb5df7e96070f1f728ff7885443646ebba703d4
Gitweb:     https://git.kernel.org/tip/cbb5df7e96070f1f728ff7885443646ebba703d4
Author:     Jiri Olsa <jolsa@kernel.org>
AuthorDate: Mon, 22 Oct 2018 11:30:15 +0200
Committer:  Arnaldo Carvalho de Melo <acme@redhat.com>
CommitDate: Mon, 22 Oct 2018 12:37:52 -0300

perf stat: Poll for monitored tasks being alive

Adding the check for tasks we monitor via -p/-t options, and finish stat
if there's no longer task to monitor.

Requested-by: Stephane Eranian <eranian@google.com>
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
Cc: Alexander Shishkin <alexander.shishkin@linux.intel.com>
Cc: Jin Yao <yao.jin@linux.intel.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Link: http://lkml.kernel.org/r/20181022093015.9106-1-jolsa@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>
---
 tools/perf/builtin-stat.c | 24 ++++++++++++++++++++++++
 1 file changed, 24 insertions(+)

diff --git a/tools/perf/builtin-stat.c b/tools/perf/builtin-stat.c
index b86aba1c8028..d1028d7755bb 100644
--- a/tools/perf/builtin-stat.c
+++ b/tools/perf/builtin-stat.c
@@ -409,6 +409,28 @@ static struct perf_evsel *perf_evsel__reset_weak_group(struct perf_evsel *evsel)
 	return leader;
 }
 
+static bool is_target_alive(struct target *_target,
+			    struct thread_map *threads)
+{
+	struct stat st;
+	int i;
+
+	if (!target__has_task(_target))
+		return true;
+
+	for (i = 0; i < threads->nr; i++) {
+		char path[PATH_MAX];
+
+		scnprintf(path, PATH_MAX, "%s/%d", procfs__mountpoint(),
+			  threads->map[i].pid);
+
+		if (!stat(path, &st))
+			return true;
+	}
+
+	return false;
+}
+
 static int __run_perf_stat(int argc, const char **argv, int run_idx)
 {
 	int interval = stat_config.interval;
@@ -579,6 +601,8 @@ try_again:
 		enable_counters();
 		while (!done) {
 			nanosleep(&ts, NULL);
+			if (!is_target_alive(&target, evsel_list->threads))
+				break;
 			if (timeout)
 				break;
 			if (interval) {