perf top tui: Wait till the first sample to refresh the screen.

Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Ingo Molnar <mingo@elte.hu>
Cc: Mike Galbraith <efault@gmx.de>
Cc: Paul Mackerras <paulus@samba.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Stephane Eranian <eranian@google.com>
Cc: Tom Zanussi <tzanussi@gmail.com>
LKML-Reference: <new-submission>
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

2 files changed, 20 insertions, 2 deletions

diff --git a/tools/perf/builtin-top.c b/tools/perf/builtin-top.c
index 0b07cc30b66..417f757e3cb 100644
--- a/tools/perf/builtin-top.c
+++ b/tools/perf/builtin-top.c
@@ -72,6 +72,7 @@ static struct perf_top top = {
         .target_tid             = -1,
         .active_symbols         = LIST_HEAD_INIT(top.active_symbols),
         .active_symbols_lock    = PTHREAD_MUTEX_INITIALIZER,
+        .active_symbols_cond    = PTHREAD_COND_INITIALIZER,
         .freq                   = 1000, /* 1 KHz */
 };
 
@@ -577,7 +578,17 @@ static void handle_keypress(struct perf_session *session, int c)
 
 static void *display_thread_tui(void *arg __used)
 {
-        perf_top__tui_browser(&top);
+        int err = 0;
+        pthread_mutex_lock(&top.active_symbols_lock);
+        while (list_empty(&top.active_symbols)) {
+                err = pthread_cond_wait(&top.active_symbols_cond,
+                                        &top.active_symbols_lock);
+                if (err)
+                        break;
+        }
+        pthread_mutex_unlock(&top.active_symbols_lock);
+        if (!err)
+                perf_top__tui_browser(&top);
         exit_browser(0);
         exit(0);
         return NULL;
@@ -776,8 +787,14 @@ static void perf_event__process_sample(const union perf_event *event,
                 syme->count[evsel->idx]++;
                 record_precise_ip(syme, evsel->idx, ip);
                 pthread_mutex_lock(&top.active_symbols_lock);
-                if (list_empty(&syme->node) || !syme->node.next)
+                if (list_empty(&syme->node) || !syme->node.next) {
+                        static bool first = true;
                         __list_insert_active_sym(syme);
+                        if (first) {
+                                pthread_cond_broadcast(&top.active_symbols_cond);
+                                first = false;
+                        }
+                }
                 pthread_mutex_unlock(&top.active_symbols_lock);
         }
 }
diff --git a/tools/perf/util/top.h b/tools/perf/util/top.h
index e8d28e2ecdb..96d1cb78af0 100644
--- a/tools/perf/util/top.h
+++ b/tools/perf/util/top.h
@@ -35,6 +35,7 @@ struct perf_top {
          */
         struct list_head   active_symbols;
         pthread_mutex_t    active_symbols_lock;
+        pthread_cond_t     active_symbols_cond;
         u64                samples;
         u64                kernel_samples, us_samples;
         u64                exact_samples;