[PATCH v2 1/6] perf sched timehist: Split is_idle_sample()

Namhyung Kim
2016-12-08T14:49:15Z

The is_idle_sample() function actually does more than determining
whether sample come from idle task. Split the callchain part into
save_task_callchain() to make it clearer.

Also checking prev_pid from trace data looks preferred than just
checking sample->pid since it's possible, although rare, to have invalid
0 pid/tid on scheduling an exiting task.

Signed-off-by: Namhyung Kim <namhyung@kernel.org>
---
tools/perf/builtin-sched.c | 39 ++++++++++++++++++++-------------------
1 file changed, 20 insertions(+), 19 deletions(-)

diff --git a/tools/perf/builtin-sched.c b/tools/perf/builtin-sched.c
index 1a3f1be93372..46aa4705f321 100644
--- a/tools/perf/builtin-sched.c
+++ b/tools/perf/builtin-sched.c
@@ -1939,39 +1939,40 @@ static void timehist_update_runtime_stats(struct thread_runtime *r,
r->total_run_time += r->dt_run;
}

-static bool is_idle_sample(struct perf_sched *sched,
- struct perf_sample *sample,
- struct perf_evsel *evsel,
- struct machine *machine)
+static bool is_idle_sample(struct perf_sample *sample,
+ struct perf_evsel *evsel)
{
- struct thread *thread;
- struct callchain_cursor *cursor = &callchain_cursor;
-
/* pid 0 == swapper == idle task */
- if (sample->pid == 0)
- return true;
+ if (strcmp(perf_evsel__name(evsel), "sched:sched_switch") == 0)
+ return (perf_evsel__intval(evsel, sample, "prev_pid") == 0);

- if (strcmp(perf_evsel__name(evsel), "sched:sched_switch") == 0) {
- if (perf_evsel__intval(evsel, sample, "prev_pid") == 0)
- return true;
- }
+ return (sample->pid == 0);
+}
+
+static void save_task_callchain(struct perf_sched *sched,
+ struct perf_sample *sample,
+ struct perf_evsel *evsel,
+ struct machine *machine)
+{
+ struct callchain_cursor *cursor = &callchain_cursor;
+ struct thread *thread;

/* want main thread for process - has maps */
thread = machine__findnew_thread(machine, sample->pid, sample->pid);
if (thread == NULL) {
pr_debug("Failed to get thread for pid %d.\n", sample->pid);
- return false;
+ return;
}

if (!symbol_conf.use_callchain || sample->callchain == NULL)
- return false;
+ return;

if (thread__resolve_callchain(thread, cursor, evsel, sample,
NULL, NULL, sched->max_stack + 2) != 0) {
if (verbose)
error("Failed to resolve callchain. Skipping\n");

- return false;
+ return;
}

callchain_cursor_commit(cursor);
@@ -1994,8 +1995,6 @@ static bool is_idle_sample(struct perf_sched *sched,

callchain_cursor_advance(cursor);
}
-
- return false;
}

/*
@@ -2111,7 +2110,7 @@ static struct thread *timehist_get_thread(struct perf_sched *sched,
{
struct thread *thread;

- if (is_idle_sample(sched, sample, evsel, machine)) {
+ if (is_idle_sample(sample, evsel)) {
thread = get_idle_thread(sample->cpu);
if (thread == NULL)
pr_err("Failed to get idle thread for cpu %d.\n", sample->cpu);
@@ -2124,6 +2123,8 @@ static struct thread *timehist_get_thread(struct perf_sched *sched,
pr_debug("Failed to get thread for tid %d. skipping sample.\n",
sample->tid);
}
+
+ save_task_callchain(sched, sample, evsel, machine);
}

return thread;
--
2.10.1