#1969: scheduler: reduce calls to get the current time

src/vt/runtime/component/component_pack.cc

@@ -110,6 +110,14 @@ int ComponentPack::progress(TimeType current_time) {
   return total;
 }
 
+bool ComponentPack::needsCurrentTime() {
+  bool needs_time = false;
+  for (auto&& pollable : pollable_components_) {
+    needs_time = needs_time || pollable->needsCurrentTime();
+  }
+  return needs_time;
+}
+
 std::list<int> ComponentPack::topoSort() {
   std::list<int> order;
 

src/vt/runtime/component/component_pack.h

@@ -116,6 +116,13 @@ struct ComponentPack {
    */
   int progress(TimeType current_time);
 
+  /**
+   * \internal \brief Needs current time
+   *
+   * \return whether any component needs the current time on the progress call
+   */
+  bool needsCurrentTime();
+
   /**
    * \internal \brief Extract the first component from a running pack that
    * matches \c name.

src/vt/runtime/component/progressable.h

@@ -62,6 +62,13 @@ struct Progressable {
    * \return the number of units executed---zero if no progress was made
    */
   virtual int progress(TimeType current_time) = 0;
+
+  /**
+   * \brief Whether the component needs the current time
+   *
+   * \return whether it needs time
+   */
+  virtual bool needsCurrentTime() { return false; }
 };
 
 }}} /* end namespace vt::runtime::component */

src/vt/runtime/runtime.h

@@ -129,6 +129,13 @@ struct Runtime {
    */
   int progress(TimeType current_time) { if (p_) return p_->progress(current_time); else return 0; }
 
+  /**
+   * \brief Check if any pollable components needs the current time
+   *
+   * \return whether it needs the current time
+   */
+  bool needsCurrentTime() { if (p_) return p_->needsCurrentTime(); else return false; }
+
   /**
    * \brief Check if runtime has terminated
    *

src/vt/scheduler/scheduler.cc

@@ -109,6 +109,11 @@ Scheduler::Scheduler()
 # endif
 }
 
+void Scheduler::startup() {
+  special_progress_ =
+    theConfig()->vt_sched_progress_han != 0 or progress_time_enabled_;
+}
+
 void Scheduler::preDiagnostic() {
   vtLiveTime.stop();
 }
@@ -236,23 +241,28 @@ void Scheduler::runProgress(bool msg_only, TimeType current_time) {
     printMemoryUsage();
   }
 
-  // Reset count of processed handlers since the last time progress was invoked
-  processed_after_last_progress_ = 0;
-  last_progress_time_ = timing::getCurrentTime();
-
+  if (special_progress_) {
+    // Reset count of processed handlers since the last time progress was invoked
+    processed_after_last_progress_ = 0;
+    last_progress_time_ = timing::getCurrentTime();
+  }
 }
 
 void Scheduler::runSchedulerOnceImpl(bool msg_only) {
-  auto current_time = timing::getCurrentTime();
-  auto time_since_last_progress = current_time - last_progress_time_;
-  if (
-    work_queue_.empty() or
-    shouldCallProgress(processed_after_last_progress_, time_since_last_progress)
-  ) {
-    runProgress(msg_only, current_time);
+  if (special_progress_) {
+    auto current_time = timing::getCurrentTime();
+    auto time_since_last_progress = current_time - last_progress_time_;
+    if (shouldCallProgress(processed_after_last_progress_, time_since_last_progress)) {
+      runProgress(msg_only, current_time);
+    }
+  } else if (work_queue_.empty()) {
+    if (curRT->needsCurrentTime()) {
+      runProgress(msg_only, timing::getCurrentTime());
+    } else {
+      runProgress(msg_only, TimeType{0});
+    }
   }
 
-
   if (not work_queue_.empty()) {
     queueSizeGauge.update(work_queue_.size());
 

src/vt/scheduler/scheduler.h

@@ -135,6 +135,7 @@ struct Scheduler : runtime::component::Component<Scheduler> {
   std::string name() override { return "Scheduler"; }
 
   void preDiagnostic() override;
+  void startup() override;
 
   /**
    * \internal \brief Check for termination when running on a single node
@@ -423,6 +424,8 @@ struct Scheduler : runtime::component::Component<Scheduler> {
   std::size_t threshold_memory_usage_ = 0;
   std::size_t last_memory_usage_poll_ = 0;
 
+  bool special_progress_ = false; /**< time-based/k-handler progress enabled */
+
   // Access to triggerEvent.
   template <typename Callable>
   friend void vt::runInEpochRooted(Callable&& fn);

src/vt/timetrigger/time_trigger_manager.cc

@@ -92,4 +92,8 @@ int TimeTriggerManager::progress(TimeType current_time) {
   return 0;
 }
 
+bool TimeTriggerManager::needsCurrentTime() {
+  return queue_.size() != 0;
+}
+
 }} /* end namespace vt::timetrigger */

src/vt/timetrigger/time_trigger_manager.h

@@ -75,6 +75,8 @@ struct TimeTriggerManager
 
   int progress(TimeType current_time) override;
 
+  bool needsCurrentTime() override;
+
   /**
    * \brief Register a time-based trigger with a specific period
    *