Fix concurrent mark worker timings

src/hotspot/share/gc/shenandoah/shenandoahConcurrentMark.cpp

@@ -58,7 +58,7 @@ class ShenandoahConcurrentMarkingTask : public WorkerTask {
   void work(uint worker_id) {
     ShenandoahHeap* heap = ShenandoahHeap::heap();
     ShenandoahParallelWorkerSession worker_session(worker_id);
-    ShenandoahWorkerTimingsTracker timer(ShenandoahPhaseTimings::conc_mark, ShenandoahPhaseTimings::ParallelMark, worker_id);
+    ShenandoahWorkerTimingsTracker timer(ShenandoahPhaseTimings::conc_mark, ShenandoahPhaseTimings::ParallelMark, worker_id, true);
     ShenandoahSuspendibleThreadSetJoiner stsj(ShenandoahSuspendibleWorkers);
     ShenandoahReferenceProcessor* rp = heap->active_generation()->ref_processor();
     assert(rp != NULL, "need reference processor");

src/hotspot/share/gc/shenandoah/shenandoahPhaseTimings.cpp

@@ -310,17 +310,17 @@ void ShenandoahPhaseTimings::print_global_on(outputStream* out) const {
 }
 
 ShenandoahWorkerTimingsTracker::ShenandoahWorkerTimingsTracker(ShenandoahPhaseTimings::Phase phase,
-        ShenandoahPhaseTimings::ParPhase par_phase, uint worker_id) :
+        ShenandoahPhaseTimings::ParPhase par_phase, uint worker_id, bool cumulative) :
         _timings(ShenandoahHeap::heap()->phase_timings()),
         _phase(phase), _par_phase(par_phase), _worker_id(worker_id) {
 
-  assert(_timings->worker_data(_phase, _par_phase)->get(_worker_id) == ShenandoahWorkerData::uninitialized(),
+  assert(_timings->worker_data(_phase, _par_phase)->get(_worker_id) == ShenandoahWorkerData::uninitialized() || cumulative,
          "Should not be set yet: %s", ShenandoahPhaseTimings::phase_name(_timings->worker_par_phase(_phase, _par_phase)));
   _start_time = os::elapsedTime();
 }
 
 ShenandoahWorkerTimingsTracker::~ShenandoahWorkerTimingsTracker() {
-  _timings->worker_data(_phase, _par_phase)->set(_worker_id, os::elapsedTime() - _start_time);
+  _timings->worker_data(_phase, _par_phase)->set_or_add(_worker_id, os::elapsedTime() - _start_time);
 
   if (ShenandoahPhaseTimings::is_root_work_phase(_phase)) {
     ShenandoahPhaseTimings::Phase root_phase = _phase;

src/hotspot/share/gc/shenandoah/shenandoahPhaseTimings.hpp

@@ -259,7 +259,8 @@ class ShenandoahWorkerTimingsTracker : public StackObj {
   double _start_time;
   EventGCPhaseParallel _event;
 public:
-  ShenandoahWorkerTimingsTracker(ShenandoahPhaseTimings::Phase phase, ShenandoahPhaseTimings::ParPhase par_phase, uint worker_id);
+  ShenandoahWorkerTimingsTracker(ShenandoahPhaseTimings::Phase phase, ShenandoahPhaseTimings::ParPhase par_phase,
+                                 uint worker_id, bool cumulative = false);
   ~ShenandoahWorkerTimingsTracker();
 };