1 /*
   2  * Copyright (c) 2018, 2019, Red Hat, Inc. All rights reserved.
   3  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
   4  *
   5  * This code is free software; you can redistribute it and/or modify it
   6  * under the terms of the GNU General Public License version 2 only, as
   7  * published by the Free Software Foundation.
   8  *
   9  * This code is distributed in the hope that it will be useful, but WITHOUT
  10  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
  11  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
  12  * version 2 for more details (a copy is included in the LICENSE file that
  13  * accompanied this code).
  14  *
  15  * You should have received a copy of the GNU General Public License version
  16  * 2 along with this work; if not, write to the Free Software Foundation,
  17  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
  18  *
  19  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
  20  * or visit www.oracle.com if you need additional information or have any
  21  * questions.
  22  *
  23  */
  24 
  25 #include "precompiled.hpp"
  26 
  27 #include "gc/shenandoah/heuristics/shenandoahStaticHeuristics.hpp"
  28 #include "gc/shenandoah/shenandoahCollectionSet.hpp"
  29 #include "gc/shenandoah/shenandoahFreeSet.hpp"
  30 #include "gc/shenandoah/shenandoahHeapRegion.hpp"
  31 #include "logging/log.hpp"
  32 #include "logging/logTag.hpp"
  33 
  34 ShenandoahStaticHeuristics::ShenandoahStaticHeuristics() : ShenandoahHeuristics() {
  35   // Static heuristics may degrade to continuous if live data is larger
  36   // than free threshold. ShenandoahAllocationThreshold is supposed to break this,
  37   // but it only works if it is non-zero.
  38   SHENANDOAH_ERGO_OVERRIDE_DEFAULT(ShenandoahAllocationThreshold, 1);
  39 
  40   SHENANDOAH_ERGO_ENABLE_FLAG(ExplicitGCInvokesConcurrent);
  41   SHENANDOAH_ERGO_ENABLE_FLAG(ShenandoahImplicitGCInvokesConcurrent);
  42 
  43   // Final configuration checks
  44   SHENANDOAH_CHECK_FLAG_SET(ShenandoahLoadRefBarrier);
  45   SHENANDOAH_CHECK_FLAG_SET(ShenandoahSATBBarrier);
  46   SHENANDOAH_CHECK_FLAG_SET(ShenandoahKeepAliveBarrier);
  47   SHENANDOAH_CHECK_FLAG_SET(ShenandoahCASBarrier);
  48   SHENANDOAH_CHECK_FLAG_SET(ShenandoahCloneBarrier);
  49 }
  50 
  51 ShenandoahStaticHeuristics::~ShenandoahStaticHeuristics() {}
  52 
  53 bool ShenandoahStaticHeuristics::should_start_gc() const {
  54   ShenandoahHeap* heap = ShenandoahHeap::heap();
  55 
  56   size_t capacity = heap->max_capacity();
  57   size_t available = heap->free_set()->available();
  58   size_t threshold_available = capacity / 100 * ShenandoahFreeThreshold;
  59 
  60   if (available < threshold_available) {
  61     log_info(gc)("Trigger: Free (" SIZE_FORMAT "%s) is below free threshold (" SIZE_FORMAT "%s)",
  62                  byte_size_in_proper_unit(available),           proper_unit_for_byte_size(available),
  63                  byte_size_in_proper_unit(threshold_available), proper_unit_for_byte_size(threshold_available));
  64     return true;
  65   }
  66   return ShenandoahHeuristics::should_start_gc();
  67 }
  68 
  69 void ShenandoahStaticHeuristics::choose_collection_set_from_regiondata(ShenandoahCollectionSet* cset,
  70                                                                        RegionData* data, size_t size,
  71                                                                        size_t free) {
  72   size_t threshold = ShenandoahHeapRegion::region_size_bytes() * ShenandoahGarbageThreshold / 100;
  73 
  74   for (size_t idx = 0; idx < size; idx++) {
  75     ShenandoahHeapRegion* r = data[idx]._region;
  76     if (r->garbage() > threshold) {
  77       cset->add_region(r);
  78     }
  79   }
  80 }
  81 
  82 const char* ShenandoahStaticHeuristics::name() {
  83   return "static";
  84 }
  85 
  86 bool ShenandoahStaticHeuristics::is_diagnostic() {
  87   return false;
  88 }
  89 
  90 bool ShenandoahStaticHeuristics::is_experimental() {
  91   return false;
  92 }