1 /*
   2  * Copyright (c) 2018, Red Hat, Inc. and/or its affiliates.
   3  *
   4  * This code is free software; you can redistribute it and/or modify it
   5  * under the terms of the GNU General Public License version 2 only, as
   6  * published by the Free Software Foundation.
   7  *
   8  * This code is distributed in the hope that it will be useful, but WITHOUT
   9  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  10  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  11  * version 2 for more details (a copy is included in the LICENSE file that
  12  * accompanied this code).
  13  *
  14  * You should have received a copy of the GNU General Public License version
  15  * 2 along with this work; if not, write to the Free Software Foundation,
  16  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  17  *
  18  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  19  * or visit www.oracle.com if you need additional information or have any
  20  * questions.
  21  *
  22  */
  23 
  24 #include "precompiled.hpp"
  25 #include "gc_implementation/shenandoah/heuristics/shenandoahAggressiveHeuristics.hpp"
  26 #include "gc_implementation/shenandoah/shenandoahCollectionSet.hpp"
  27 #include "gc_implementation/shenandoah/shenandoahHeapRegion.hpp"
  28 #include "gc_implementation/shenandoah/shenandoahLogging.hpp"
  29 
  30 ShenandoahAggressiveHeuristics::ShenandoahAggressiveHeuristics() : ShenandoahHeuristics() {
  31   // Do not shortcut evacuation
  32   SHENANDOAH_ERGO_OVERRIDE_DEFAULT(ShenandoahImmediateThreshold, 100);
  33 
  34   // Aggressive runs with max speed for allocation, to capture races against mutator
  35   SHENANDOAH_ERGO_DISABLE_FLAG(ShenandoahPacing);
  36 }
  37 
  38 void ShenandoahAggressiveHeuristics::choose_collection_set_from_regiondata(ShenandoahCollectionSet* cset,
  39                                                                            RegionData* data, size_t size,
  40                                                                            size_t free) {
  41   for (size_t idx = 0; idx < size; idx++) {
  42     ShenandoahHeapRegion* r = data[idx]._region;
  43     if (r->garbage() > 0) {
  44       cset->add_region(r);
  45     }
  46   }
  47 }
  48 
  49 bool ShenandoahAggressiveHeuristics::should_start_normal_gc() const {
  50   return true;
  51 }
  52 
  53 bool ShenandoahAggressiveHeuristics::should_process_references() {
  54   if (ShenandoahRefProcFrequency == 0) return false;
  55   // Randomly process refs with 50% chance.
  56   return (os::random() & 1) == 1;
  57 }
  58 
  59 bool ShenandoahAggressiveHeuristics::should_unload_classes() {
  60   if (ShenandoahUnloadClassesFrequency == 0) return false;
  61   // Randomly unload classes with 50% chance.
  62   return (os::random() & 1) == 1;
  63 }
  64 
  65 const char* ShenandoahAggressiveHeuristics::name() {
  66   return "aggressive";
  67 }
  68 
  69 bool ShenandoahAggressiveHeuristics::is_diagnostic() {
  70   return true;
  71 }
  72 
  73 bool ShenandoahAggressiveHeuristics::is_experimental() {
  74   return false;
  75 }