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/shenandoahHeap.inline.hpp"
  30 #include "gc_implementation/shenandoah/shenandoahHeapRegion.inline.hpp"
  31 #include "gc_implementation/shenandoah/shenandoahLogging.hpp"
  32 
  33 ShenandoahStaticHeuristics::ShenandoahStaticHeuristics() : ShenandoahHeuristics() {
  34   SHENANDOAH_ERGO_ENABLE_FLAG(ExplicitGCInvokesConcurrent);
  35   SHENANDOAH_ERGO_ENABLE_FLAG(ShenandoahImplicitGCInvokesConcurrent);
  36 }
  37 
  38 ShenandoahStaticHeuristics::~ShenandoahStaticHeuristics() {}
  39 
  40 bool ShenandoahStaticHeuristics::should_start_gc() const {
  41   ShenandoahHeap* heap = ShenandoahHeap::heap();
  42 
  43   size_t max_capacity = heap->max_capacity();
  44   size_t capacity = heap->soft_max_capacity();
  45   size_t available = heap->free_set()->available();
  46 
  47   // Make sure the code below treats available without the soft tail.
  48   size_t soft_tail = max_capacity - capacity;
  49   available = (available > soft_tail) ? (available - soft_tail) : 0;
  50 
  51   size_t threshold_available = capacity / 100 * ShenandoahMinFreeThreshold;
  52 
  53   if (available < threshold_available) {
  54     log_info(gc)("Trigger: Free (" SIZE_FORMAT "%s) is below minimum threshold (" SIZE_FORMAT "%s)",
  55                  byte_size_in_proper_unit(available),           proper_unit_for_byte_size(available),
  56                  byte_size_in_proper_unit(threshold_available), proper_unit_for_byte_size(threshold_available));
  57     return true;
  58   }
  59   return ShenandoahHeuristics::should_start_gc();
  60 }
  61 
  62 void ShenandoahStaticHeuristics::choose_collection_set_from_regiondata(ShenandoahCollectionSet* cset,
  63                                                                        RegionData* data, size_t size,
  64                                                                        size_t free) {
  65   size_t threshold = ShenandoahHeapRegion::region_size_bytes() * ShenandoahGarbageThreshold / 100;
  66 
  67   for (size_t idx = 0; idx < size; idx++) {
  68     ShenandoahHeapRegion* r = data[idx]._region;
  69     if (r->garbage() > threshold) {
  70       cset->add_region(r);
  71     }
  72   }
  73 }