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