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_implementation/shenandoah/heuristics/shenandoahStaticHeuristics.hpp"
  27 #include "gc_implementation/shenandoah/shenandoahCollectionSet.hpp"
  28 #include "gc_implementation/shenandoah/shenandoahFreeSet.hpp"
  29 #include "gc_implementation/shenandoah/shenandoahHeapRegion.hpp"
  30 #include "gc_implementation/shenandoah/shenandoahLogging.hpp"
  31 
  32 ShenandoahStaticHeuristics::ShenandoahStaticHeuristics() : ShenandoahHeuristics() {
  33   // Static heuristics may degrade to continuous if live data is larger
  34   // than free threshold. ShenandoahAllocationThreshold is supposed to break this,
  35   // but it only works if it is non-zero.
  36   SHENANDOAH_ERGO_OVERRIDE_DEFAULT(ShenandoahAllocationThreshold, 1);
  37 
  38   SHENANDOAH_ERGO_ENABLE_FLAG(ExplicitGCInvokesConcurrent);
  39   SHENANDOAH_ERGO_ENABLE_FLAG(ShenandoahImplicitGCInvokesConcurrent);
  40 
  41   // Final configuration checks
  42   SHENANDOAH_CHECK_FLAG_SET(ShenandoahLoadRefBarrier);
  43   SHENANDOAH_CHECK_FLAG_SET(ShenandoahSATBBarrier);
  44   SHENANDOAH_CHECK_FLAG_SET(ShenandoahCASBarrier);
  45   SHENANDOAH_CHECK_FLAG_SET(ShenandoahCloneBarrier);
  46 }
  47 
  48 ShenandoahStaticHeuristics::~ShenandoahStaticHeuristics() {}
  49 
  50 bool ShenandoahStaticHeuristics::should_start_gc() const {
  51   ShenandoahHeap* heap = ShenandoahHeap::heap();
  52 
  53   size_t capacity = heap->max_capacity();
  54   size_t available = heap->free_set()->available();
  55   size_t threshold_available = capacity / 100 * ShenandoahFreeThreshold;
  56 
  57   if (available < threshold_available) {
  58     log_info(gc)("Trigger: Free (" SIZE_FORMAT "%s) is below free threshold (" SIZE_FORMAT "%s)",
  59                  byte_size_in_proper_unit(available),           proper_unit_for_byte_size(available),
  60                  byte_size_in_proper_unit(threshold_available), proper_unit_for_byte_size(threshold_available));
  61     return true;
  62   }
  63   return ShenandoahHeuristics::should_start_gc();
  64 }
  65 
  66 void ShenandoahStaticHeuristics::choose_collection_set_from_regiondata(ShenandoahCollectionSet* cset,
  67                                                                        RegionData* data, size_t size,
  68                                                                        size_t free) {
  69   size_t threshold = ShenandoahHeapRegion::region_size_bytes() * ShenandoahGarbageThreshold / 100;
  70 
  71   for (size_t idx = 0; idx < size; idx++) {
  72     ShenandoahHeapRegion* r = data[idx]._region;
  73     if (r->garbage() > threshold) {
  74       cset->add_region(r);
  75     }
  76   }
  77 }
  78 
  79 const char* ShenandoahStaticHeuristics::name() {
  80   return "static";
  81 }
  82 
  83 bool ShenandoahStaticHeuristics::is_diagnostic() {
  84   return false;
  85 }
  86 
  87 bool ShenandoahStaticHeuristics::is_experimental() {
  88   return false;
  89 }