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   // Aggressive evacuates everything, so it needs as much evac space as it can get
  38   SHENANDOAH_ERGO_ENABLE_FLAG(ShenandoahEvacReserveOverflow);
  39 
  40   // If class unloading is globally enabled, aggressive does unloading even with
  41   // concurrent cycles.
  42   if (ClassUnloading) {
  43     SHENANDOAH_ERGO_OVERRIDE_DEFAULT(ShenandoahUnloadClassesFrequency, 1);
  44   }
  45 }
  46 
  47 void ShenandoahAggressiveHeuristics::choose_collection_set_from_regiondata(ShenandoahCollectionSet* cset,
  48                                                                            RegionData* data, size_t size,
  49                                                                            size_t free) {
  50   for (size_t idx = 0; idx < size; idx++) {
  51     ShenandoahHeapRegion* r = data[idx]._region;
  52     if (r->garbage() > 0) {
  53       cset->add_region(r);
  54     }
  55   }
  56 }
  57 
  58 bool ShenandoahAggressiveHeuristics::should_start_normal_gc() const {
  59   log_info(gc)("Trigger: Start next cycle immediately");
  60   return true;
  61 }
  62 
  63 bool ShenandoahAggressiveHeuristics::should_process_references() {
  64   if (ShenandoahRefProcFrequency == 0) return false;
  65   // Randomly process refs with 50% chance.
  66   return (os::random() & 1) == 1;
  67 }
  68 
  69 bool ShenandoahAggressiveHeuristics::should_unload_classes() {
  70   if (ShenandoahUnloadClassesFrequency == 0) return false;
  71   // Randomly unload classes with 50% chance.
  72   return (os::random() & 1) == 1;
  73 }
  74 
  75 const char* ShenandoahAggressiveHeuristics::name() {
  76   return "aggressive";
  77 }
  78 
  79 bool ShenandoahAggressiveHeuristics::is_diagnostic() {
  80   return true;
  81 }
  82 
  83 bool ShenandoahAggressiveHeuristics::is_experimental() {
  84   return false;
  85 }