1 /*
   2  * Copyright (c) 2018, Red Hat, Inc. All rights reserved.
   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 
  26 #include "gc/shenandoah/heuristics/shenandoahAggressiveHeuristics.hpp"
  27 #include "gc/shenandoah/shenandoahCollectionSet.hpp"
  28 #include "gc/shenandoah/shenandoahHeapRegion.hpp"
  29 #include "logging/log.hpp"
  30 #include "logging/logTag.hpp"
  31 #include "runtime/os.hpp"
  32 
  33 ShenandoahAggressiveHeuristics::ShenandoahAggressiveHeuristics() : ShenandoahHeuristics() {
  34   // Do not shortcut evacuation
  35   SHENANDOAH_ERGO_OVERRIDE_DEFAULT(ShenandoahImmediateThreshold, 100);
  36 
  37   // Aggressive runs with max speed for allocation, to capture races against mutator
  38   SHENANDOAH_ERGO_DISABLE_FLAG(ShenandoahPacing);
  39 
  40   // Aggressive evacuates everything, so it needs as much evac space as it can get
  41   SHENANDOAH_ERGO_ENABLE_FLAG(ShenandoahEvacReserveOverflow);
  42 
  43   // If class unloading is globally enabled, aggressive does unloading even with
  44   // concurrent cycles.
  45   if (ClassUnloading) {
  46     SHENANDOAH_ERGO_OVERRIDE_DEFAULT(ShenandoahUnloadClassesFrequency, 1);
  47   }
  48 
  49   // Final configuration checks
  50   SHENANDOAH_CHECK_FLAG_SET(ShenandoahSATBBarrier);
  51   SHENANDOAH_CHECK_FLAG_SET(ShenandoahReadBarrier);
  52   SHENANDOAH_CHECK_FLAG_SET(ShenandoahWriteBarrier);
  53   SHENANDOAH_CHECK_FLAG_SET(ShenandoahStoreValReadBarrier);
  54   SHENANDOAH_CHECK_FLAG_SET(ShenandoahKeepAliveBarrier);
  55   SHENANDOAH_CHECK_FLAG_SET(ShenandoahCASBarrier);
  56   SHENANDOAH_CHECK_FLAG_SET(ShenandoahAcmpBarrier);
  57   SHENANDOAH_CHECK_FLAG_SET(ShenandoahCloneBarrier);
  58 }
  59 
  60 void ShenandoahAggressiveHeuristics::choose_collection_set_from_regiondata(ShenandoahCollectionSet* cset,
  61                                                                            RegionData* data, size_t size,
  62                                                                            size_t free) {
  63   for (size_t idx = 0; idx < size; idx++) {
  64     ShenandoahHeapRegion* r = data[idx]._region;
  65     if (r->garbage() > 0) {
  66       cset->add_region(r);
  67     }
  68   }
  69 }
  70 
  71 bool ShenandoahAggressiveHeuristics::should_start_normal_gc() const {
  72   log_info(gc)("Trigger: Start next cycle immediately");
  73   return true;
  74 }
  75 
  76 bool ShenandoahAggressiveHeuristics::should_process_references() {
  77   if (!can_process_references()) return false;
  78   // Randomly process refs with 50% chance.
  79   return (os::random() & 1) == 1;
  80 }
  81 
  82 bool ShenandoahAggressiveHeuristics::should_unload_classes() {
  83   if (!can_unload_classes_normal()) return false;
  84   if (has_metaspace_oom()) return true;
  85   // Randomly unload classes with 50% chance.
  86   return (os::random() & 1) == 1;
  87 }
  88 
  89 const char* ShenandoahAggressiveHeuristics::name() {
  90   return "aggressive";
  91 }
  92 
  93 bool ShenandoahAggressiveHeuristics::is_diagnostic() {
  94   return true;
  95 }
  96 
  97 bool ShenandoahAggressiveHeuristics::is_experimental() {
  98   return false;
  99 }