--- /dev/null	2018-11-30 10:10:44.238550338 +0100
+++ new/src/hotspot/share/gc/shenandoah/shenandoahWorkerPolicy.cpp	2018-11-30 10:24:02.262630235 +0100
@@ -0,0 +1,157 @@
+/*
+ * Copyright (c) 2017, 2018, Red Hat, Inc. All rights reserved.
+ *
+ * This code is free software; you can redistribute it and/or modify it
+ * under the terms of the GNU General Public License version 2 only, as
+ * published by the Free Software Foundation.
+ *
+ * This code is distributed in the hope that it will be useful, but WITHOUT
+ * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
+ * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
+ * version 2 for more details (a copy is included in the LICENSE file that
+ * accompanied this code).
+ *
+ * You should have received a copy of the GNU General Public License version
+ * 2 along with this work; if not, write to the Free Software Foundation,
+ * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
+ *
+ * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
+ * or visit www.oracle.com if you need additional information or have any
+ * questions.
+ *
+ */
+
+#include "precompiled.hpp"
+
+#include "gc/shared/adaptiveSizePolicy.hpp"
+#include "gc/shenandoah/shenandoahWorkerPolicy.hpp"
+#include "runtime/thread.hpp"
+
+uint ShenandoahWorkerPolicy::_prev_par_marking     = 0;
+uint ShenandoahWorkerPolicy::_prev_conc_marking    = 0;
+uint ShenandoahWorkerPolicy::_prev_conc_evac       = 0;
+uint ShenandoahWorkerPolicy::_prev_fullgc          = 0;
+uint ShenandoahWorkerPolicy::_prev_degengc         = 0;
+uint ShenandoahWorkerPolicy::_prev_stw_traversal   = 0;
+uint ShenandoahWorkerPolicy::_prev_conc_traversal  = 0;
+uint ShenandoahWorkerPolicy::_prev_conc_update_ref = 0;
+uint ShenandoahWorkerPolicy::_prev_par_update_ref  = 0;
+uint ShenandoahWorkerPolicy::_prev_conc_cleanup    = 0;
+uint ShenandoahWorkerPolicy::_prev_conc_reset      = 0;
+
+uint ShenandoahWorkerPolicy::calc_workers_for_init_marking() {
+  uint active_workers = (_prev_par_marking == 0) ? ParallelGCThreads : _prev_par_marking;
+
+  _prev_par_marking =
+    AdaptiveSizePolicy::calc_active_workers(ParallelGCThreads,
+                                            active_workers,
+                                            Threads::number_of_non_daemon_threads());
+  return _prev_par_marking;
+}
+
+uint ShenandoahWorkerPolicy::calc_workers_for_conc_marking() {
+  uint active_workers = (_prev_conc_marking == 0) ?  ConcGCThreads : _prev_conc_marking;
+  _prev_conc_marking =
+    AdaptiveSizePolicy::calc_active_conc_workers(ConcGCThreads,
+                                                 active_workers,
+                                                 Threads::number_of_non_daemon_threads());
+  return _prev_conc_marking;
+}
+
+// Reuse the calculation result from init marking
+uint ShenandoahWorkerPolicy::calc_workers_for_final_marking() {
+  return _prev_par_marking;
+}
+
+// Calculate workers for concurrent evacuation (concurrent GC)
+uint ShenandoahWorkerPolicy::calc_workers_for_conc_evac() {
+  uint active_workers = (_prev_conc_evac == 0) ? ConcGCThreads : _prev_conc_evac;
+  _prev_conc_evac =
+    AdaptiveSizePolicy::calc_active_conc_workers(ConcGCThreads,
+                                                 active_workers,
+                                                 Threads::number_of_non_daemon_threads());
+  return _prev_conc_evac;
+}
+
+// Calculate workers for parallel fullgc
+uint ShenandoahWorkerPolicy::calc_workers_for_fullgc() {
+  uint active_workers = (_prev_fullgc == 0) ?  ParallelGCThreads : _prev_fullgc;
+  _prev_fullgc =
+    AdaptiveSizePolicy::calc_active_workers(ParallelGCThreads,
+                                            active_workers,
+                                            Threads::number_of_non_daemon_threads());
+  return _prev_fullgc;
+}
+
+// Calculate workers for parallel degenerated gc
+uint ShenandoahWorkerPolicy::calc_workers_for_stw_degenerated() {
+  uint active_workers = (_prev_degengc == 0) ?  ParallelGCThreads : _prev_degengc;
+  _prev_degengc =
+    AdaptiveSizePolicy::calc_active_workers(ParallelGCThreads,
+                                            active_workers,
+                                            Threads::number_of_non_daemon_threads());
+  return _prev_degengc;
+}
+
+// Calculate workers for Stop-the-world traversal GC
+uint ShenandoahWorkerPolicy::calc_workers_for_stw_traversal() {
+  uint active_workers = (_prev_stw_traversal == 0) ? ParallelGCThreads : _prev_stw_traversal;
+  _prev_stw_traversal =
+    AdaptiveSizePolicy::calc_active_workers(ParallelGCThreads,
+                                            active_workers,
+                                            Threads::number_of_non_daemon_threads());
+  return _prev_stw_traversal;
+}
+
+// Calculate workers for concurent traversal GC
+uint ShenandoahWorkerPolicy::calc_workers_for_conc_traversal() {
+  uint active_workers = (_prev_conc_traversal == 0) ? ConcGCThreads : _prev_conc_traversal;
+  _prev_conc_traversal =
+    AdaptiveSizePolicy::calc_active_conc_workers(ConcGCThreads,
+                                                 active_workers,
+                                                 Threads::number_of_non_daemon_threads());
+  return _prev_conc_traversal;
+}
+
+// Calculate workers for concurrent reference update
+uint ShenandoahWorkerPolicy::calc_workers_for_conc_update_ref() {
+  uint active_workers = (_prev_conc_update_ref == 0) ? ConcGCThreads : _prev_conc_update_ref;
+  _prev_conc_update_ref =
+    AdaptiveSizePolicy::calc_active_conc_workers(ConcGCThreads,
+                                                 active_workers,
+                                                 Threads::number_of_non_daemon_threads());
+  return _prev_conc_update_ref;
+}
+
+// Calculate workers for parallel reference update
+uint ShenandoahWorkerPolicy::calc_workers_for_final_update_ref() {
+  uint active_workers = (_prev_par_update_ref == 0) ? ParallelGCThreads : _prev_par_update_ref;
+  _prev_par_update_ref =
+    AdaptiveSizePolicy::calc_active_workers(ParallelGCThreads,
+                                            active_workers,
+                                            Threads::number_of_non_daemon_threads());
+  return _prev_par_update_ref;
+}
+
+uint ShenandoahWorkerPolicy::calc_workers_for_conc_preclean() {
+  // Precleaning is single-threaded
+  return 1;
+}
+
+uint ShenandoahWorkerPolicy::calc_workers_for_conc_cleanup() {
+  uint active_workers = (_prev_conc_cleanup == 0) ? ConcGCThreads : _prev_conc_cleanup;
+  _prev_conc_cleanup =
+          AdaptiveSizePolicy::calc_active_conc_workers(ConcGCThreads,
+                                                       active_workers,
+                                                       Threads::number_of_non_daemon_threads());
+  return _prev_conc_cleanup;
+}
+
+uint ShenandoahWorkerPolicy::calc_workers_for_conc_reset() {
+  uint active_workers = (_prev_conc_reset == 0) ? ConcGCThreads : _prev_conc_reset;
+  _prev_conc_reset =
+          AdaptiveSizePolicy::calc_active_conc_workers(ConcGCThreads,
+                                                       active_workers,
+                                                       Threads::number_of_non_daemon_threads());
+  return _prev_conc_reset;
+}