perf sched timehist: Split is_idle_sample()

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>
Acked-by: David Ahern <dsahern@gmail.com>
Cc: Andi Kleen <andi@firstfloor.org>
Cc: Jiri Olsa <jolsa@kernel.org>
Cc: Minchan Kim <minchan@kernel.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Link: http://lkml.kernel.org/r/20161208144755.16673-2-namhyung@kernel.org
[ Remove some needless () in some return statements ]
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

diff --git a/tools/perf/builtin-sched.c b/tools/perf/builtin-sched.c
index 1a3f1be93372fe3ef3ddb4ffd7cf427c9b8392cd..966eddce16093a05aae6c44b812654dbd7365151 100644 (file)
--- 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;