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/shenandoahHeapRegion.hpp"
  30 #include "logging/log.hpp"
  31 #include "logging/logTag.hpp"
  32 
  33 ShenandoahCompactHeuristics::ShenandoahCompactHeuristics() : ShenandoahHeuristics() {
  34   SHENANDOAH_ERGO_ENABLE_FLAG(ExplicitGCInvokesConcurrent);
  35   SHENANDOAH_ERGO_ENABLE_FLAG(ShenandoahImplicitGCInvokesConcurrent);
  36   SHENANDOAH_ERGO_ENABLE_FLAG(ShenandoahUncommit);
  37   SHENANDOAH_ERGO_ENABLE_FLAG(ShenandoahAlwaysClearSoftRefs);
  38   SHENANDOAH_ERGO_OVERRIDE_DEFAULT(ShenandoahAllocationThreshold,  10);
  39   SHENANDOAH_ERGO_OVERRIDE_DEFAULT(ShenandoahImmediateThreshold,   100);
  40   SHENANDOAH_ERGO_OVERRIDE_DEFAULT(ShenandoahUncommitDelay,        1000);
  41   SHENANDOAH_ERGO_OVERRIDE_DEFAULT(ShenandoahGuaranteedGCInterval, 30000);
  42   SHENANDOAH_ERGO_OVERRIDE_DEFAULT(ShenandoahGarbageThreshold,     10);
  43 }
  44 
  45 bool ShenandoahCompactHeuristics::should_start_normal_gc() const {
  46   ShenandoahHeap* heap = ShenandoahHeap::heap();
  47 
  48   size_t available = heap->free_set()->available();
  49   size_t threshold_bytes_allocated = heap->capacity() * ShenandoahAllocationThreshold / 100;
  50   size_t min_threshold = ShenandoahMinFreeThreshold * heap->capacity() / 100;
  51 
  52   if (available < min_threshold) {
  53     log_info(gc)("Trigger: Free (" SIZE_FORMAT "M) is below minimum threshold (" SIZE_FORMAT "M)",
  54                  available / M, min_threshold / M);
  55     return true;
  56   }
  57 
  58   if (available < threshold_bytes_allocated) {
  59     log_info(gc)("Trigger: Free (" SIZE_FORMAT "M) is lower than allocated recently (" SIZE_FORMAT "M)",
  60                  available / M, threshold_bytes_allocated / M);
  61     return true;
  62   }
  63 
  64   size_t bytes_allocated = heap->bytes_allocated_since_gc_start();
  65   if (bytes_allocated > threshold_bytes_allocated) {
  66     log_info(gc)("Trigger: Allocated since last cycle (" SIZE_FORMAT "M) is larger than allocation threshold (" SIZE_FORMAT "M)",
  67                  bytes_allocated / M, threshold_bytes_allocated / M);
  68     return true;
  69   }
  70 
  71   return ShenandoahHeuristics::should_start_normal_gc();
  72 }
  73 
  74 void ShenandoahCompactHeuristics::choose_collection_set_from_regiondata(ShenandoahCollectionSet* cset,
  75                                                                         RegionData* data, size_t size,
  76                                                                         size_t actual_free) {
  77   // Do not select too large CSet that would overflow the available free space
  78   size_t max_cset = actual_free * 3 / 4;
  79 
  80   log_info(gc, ergo)("CSet Selection. Actual Free: " SIZE_FORMAT "M, Max CSet: " SIZE_FORMAT "M",
  81                      actual_free / M, max_cset / M);
  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 }
  95 
  96 const char* ShenandoahCompactHeuristics::name() {
  97   return "compact";
  98 }
  99 
 100 bool ShenandoahCompactHeuristics::is_diagnostic() {
 101   return false;
 102 }
 103 
 104 bool ShenandoahCompactHeuristics::is_experimental() {
 105   return false;
 106 }