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/shenandoahStaticHeuristics.hpp"
  27 #include "gc/shenandoah/shenandoahCollectionSet.hpp"
  28 #include "gc/shenandoah/shenandoahFreeSet.hpp"
  29 #include "gc/shenandoah/shenandoahHeapRegion.hpp"
  30 #include "logging/log.hpp"
  31 #include "logging/logTag.hpp"
  32 
  33 ShenandoahStaticHeuristics::ShenandoahStaticHeuristics() : ShenandoahHeuristics() {
  34   // Static heuristics may degrade to continuous if live data is larger
  35   // than free threshold. ShenandoahAllocationThreshold is supposed to break this,
  36   // but it only works if it is non-zero.
  37   SHENANDOAH_ERGO_OVERRIDE_DEFAULT(ShenandoahAllocationThreshold, 1);
  38 
  39   SHENANDOAH_ERGO_ENABLE_FLAG(ExplicitGCInvokesConcurrent);
  40   SHENANDOAH_ERGO_ENABLE_FLAG(ShenandoahImplicitGCInvokesConcurrent);
  41 
  42   // Final configuration checks
  43   SHENANDOAH_CHECK_FLAG_SET(ShenandoahLoadRefBarrier);
  44   SHENANDOAH_CHECK_FLAG_SET(ShenandoahSATBBarrier);
  45   SHENANDOAH_CHECK_FLAG_SET(ShenandoahKeepAliveBarrier);
  46   SHENANDOAH_CHECK_FLAG_SET(ShenandoahCASBarrier);
  47   SHENANDOAH_CHECK_FLAG_SET(ShenandoahCloneBarrier);
  48 }
  49 
  50 ShenandoahStaticHeuristics::~ShenandoahStaticHeuristics() {}
  51 
  52 bool ShenandoahStaticHeuristics::should_start_normal_gc() const {
  53   ShenandoahHeap* heap = ShenandoahHeap::heap();
  54 
  55   size_t capacity = heap->max_capacity();
  56   size_t available = heap->free_set()->available();
  57   size_t threshold_available = capacity / 100 * ShenandoahFreeThreshold;
  58 
  59   if (available < threshold_available) {
  60     log_info(gc)("Trigger: Free (" SIZE_FORMAT "M) is below free threshold (" SIZE_FORMAT "M)",
  61                  available / M, threshold_available / M);
  62     return true;
  63   }
  64   return ShenandoahHeuristics::should_start_normal_gc();
  65 }
  66 
  67 void ShenandoahStaticHeuristics::choose_collection_set_from_regiondata(ShenandoahCollectionSet* cset,
  68                                                                        RegionData* data, size_t size,
  69                                                                        size_t free) {
  70   size_t threshold = ShenandoahHeapRegion::region_size_bytes() * ShenandoahGarbageThreshold / 100;
  71 
  72   for (size_t idx = 0; idx < size; idx++) {
  73     ShenandoahHeapRegion* r = data[idx]._region;
  74     if (r->garbage() > threshold) {
  75       cset->add_region(r);
  76     }
  77   }
  78 }
  79 
  80 const char* ShenandoahStaticHeuristics::name() {
  81   return "static";
  82 }
  83 
  84 bool ShenandoahStaticHeuristics::is_diagnostic() {
  85   return false;
  86 }
  87 
  88 bool ShenandoahStaticHeuristics::is_experimental() {
  89   return false;
  90 }