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/shenandoahCollectionSet.hpp"
  27 #include "gc/shenandoah/heuristics/shenandoahCompactHeuristics.hpp"
  28 #include "gc/shenandoah/shenandoahFreeSet.hpp"
  29 #include "gc/shenandoah/shenandoahHeap.inline.hpp"
  30 #include "gc/shenandoah/shenandoahHeapRegion.inline.hpp"
  31 #include "logging/log.hpp"
  32 #include "logging/logTag.hpp"
  33 
  34 ShenandoahCompactHeuristics::ShenandoahCompactHeuristics() : ShenandoahHeuristics() {
  35   SHENANDOAH_ERGO_ENABLE_FLAG(ExplicitGCInvokesConcurrent);
  36   SHENANDOAH_ERGO_ENABLE_FLAG(ShenandoahImplicitGCInvokesConcurrent);
  37   SHENANDOAH_ERGO_ENABLE_FLAG(ShenandoahUncommit);
  38   SHENANDOAH_ERGO_ENABLE_FLAG(ShenandoahAlwaysClearSoftRefs);
  39   SHENANDOAH_ERGO_OVERRIDE_DEFAULT(ShenandoahAllocationThreshold,  10);
  40   SHENANDOAH_ERGO_OVERRIDE_DEFAULT(ShenandoahImmediateThreshold,   100);
  41   SHENANDOAH_ERGO_OVERRIDE_DEFAULT(ShenandoahUncommitDelay,        1000);
  42   SHENANDOAH_ERGO_OVERRIDE_DEFAULT(ShenandoahGuaranteedGCInterval, 30000);
  43   SHENANDOAH_ERGO_OVERRIDE_DEFAULT(ShenandoahGarbageThreshold,     10);
  44 }
  45 
  46 bool ShenandoahCompactHeuristics::should_start_gc() const {
  47   ShenandoahHeap* heap = ShenandoahHeap::heap();
  48 
  49   size_t capacity = heap->max_capacity();
  50   size_t available = heap->free_set()->available();
  51 
  52   size_t threshold_bytes_allocated = capacity / 100 * ShenandoahAllocationThreshold;
  53   size_t min_threshold = capacity / 100 * ShenandoahMinFreeThreshold;
  54 
  55   if (available < min_threshold) {
  56     log_info(gc)("Trigger: Free (" SIZE_FORMAT "%s) is below minimum threshold (" SIZE_FORMAT "%s)",
  57                  byte_size_in_proper_unit(available),     proper_unit_for_byte_size(available),
  58                  byte_size_in_proper_unit(min_threshold), proper_unit_for_byte_size(min_threshold));
  59     return true;
  60   }
  61 
  62   size_t bytes_allocated = heap->bytes_allocated_since_gc_start();
  63   if (bytes_allocated > threshold_bytes_allocated) {
  64     log_info(gc)("Trigger: Allocated since last cycle (" SIZE_FORMAT "%s) is larger than allocation threshold (" SIZE_FORMAT "%s)",
  65                  byte_size_in_proper_unit(bytes_allocated),           proper_unit_for_byte_size(bytes_allocated),
  66                  byte_size_in_proper_unit(threshold_bytes_allocated), proper_unit_for_byte_size(threshold_bytes_allocated));
  67     return true;
  68   }
  69 
  70   return ShenandoahHeuristics::should_start_gc();
  71 }
  72 
  73 void ShenandoahCompactHeuristics::choose_collection_set_from_regiondata(ShenandoahCollectionSet* cset,
  74                                                                         RegionData* data, size_t size,
  75                                                                         size_t actual_free) {
  76   // Do not select too large CSet that would overflow the available free space
  77   size_t max_cset = actual_free * 3 / 4;
  78 
  79   log_info(gc, ergo)("CSet Selection. Actual Free: " SIZE_FORMAT "%s, Max CSet: " SIZE_FORMAT "%s",
  80                      byte_size_in_proper_unit(actual_free), proper_unit_for_byte_size(actual_free),
  81                      byte_size_in_proper_unit(max_cset),    proper_unit_for_byte_size(max_cset));
  82 
  83   size_t threshold = ShenandoahHeapRegion::region_size_bytes() * ShenandoahGarbageThreshold / 100;
  84 
  85   size_t live_cset = 0;
  86   for (size_t idx = 0; idx < size; idx++) {
  87     ShenandoahHeapRegion* r = data[idx]._region;
  88     size_t new_cset = live_cset + r->get_live_data_bytes();
  89     if (new_cset < max_cset && r->garbage() > threshold) {
  90       live_cset = new_cset;
  91       cset->add_region(r);
  92     }
  93   }
  94 }