1 /*
  2  * Copyright (c) 2018, 2019, Red Hat, Inc. All rights reserved.
  3  * Copyright Amazon.com Inc. or its affiliates. All Rights Reserved.
  4  * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
  5  *
  6  * This code is free software; you can redistribute it and/or modify it
  7  * under the terms of the GNU General Public License version 2 only, as
  8  * published by the Free Software Foundation.
  9  *
 10  * This code is distributed in the hope that it will be useful, but WITHOUT
 11  * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 12  * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 13  * version 2 for more details (a copy is included in the LICENSE file that
 14  * accompanied this code).
 15  *
 16  * You should have received a copy of the GNU General Public License version
 17  * 2 along with this work; if not, write to the Free Software Foundation,
 18  * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 19  *
 20  * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 21  * or visit www.oracle.com if you need additional information or have any
 22  * questions.
 23  *
 24  */
 25 
 26 #include "precompiled.hpp"
 27 
 28 #include "gc/shenandoah/shenandoahCollectionSet.hpp"
 29 #include "gc/shenandoah/heuristics/shenandoahCompactHeuristics.hpp"
 30 #include "gc/shenandoah/shenandoahFreeSet.hpp"
 31 #include "gc/shenandoah/shenandoahHeap.inline.hpp"
 32 #include "gc/shenandoah/shenandoahHeapRegion.inline.hpp"
 33 #include "logging/log.hpp"
 34 #include "logging/logTag.hpp"
 35 
 36 ShenandoahCompactHeuristics::ShenandoahCompactHeuristics(ShenandoahSpaceInfo* space_info) :
 37   ShenandoahHeuristics(space_info) {
 38   SHENANDOAH_ERGO_ENABLE_FLAG(ExplicitGCInvokesConcurrent);
 39   SHENANDOAH_ERGO_ENABLE_FLAG(ShenandoahImplicitGCInvokesConcurrent);
 40   SHENANDOAH_ERGO_ENABLE_FLAG(ShenandoahUncommit);
 41   SHENANDOAH_ERGO_ENABLE_FLAG(ShenandoahAlwaysClearSoftRefs);
 42   SHENANDOAH_ERGO_OVERRIDE_DEFAULT(ShenandoahAllocationThreshold,  10);
 43   SHENANDOAH_ERGO_OVERRIDE_DEFAULT(ShenandoahImmediateThreshold,   100);
 44   SHENANDOAH_ERGO_OVERRIDE_DEFAULT(ShenandoahUncommitDelay,        1000);
 45   SHENANDOAH_ERGO_OVERRIDE_DEFAULT(ShenandoahGuaranteedGCInterval, 30000);
 46   SHENANDOAH_ERGO_OVERRIDE_DEFAULT(ShenandoahGarbageThreshold,     10);
 47 }
 48 
 49 bool ShenandoahCompactHeuristics::should_start_gc() {
 50   size_t max_capacity = _space_info->max_capacity();
 51   size_t capacity = _space_info->soft_max_capacity();
 52   size_t available = _space_info->available();
 53 
 54   // Make sure the code below treats available without the soft tail.
 55   size_t soft_tail = max_capacity - capacity;
 56   available = (available > soft_tail) ? (available - soft_tail) : 0;
 57 
 58   size_t threshold_bytes_allocated = capacity / 100 * ShenandoahAllocationThreshold;
 59   size_t min_threshold = capacity / 100 * ShenandoahMinFreeThreshold;
 60 
 61   if (available < min_threshold) {
 62     log_info(gc)("Trigger: Free (" SIZE_FORMAT "%s) is below minimum threshold (" SIZE_FORMAT "%s)",
 63                  byte_size_in_proper_unit(available),     proper_unit_for_byte_size(available),
 64                  byte_size_in_proper_unit(min_threshold), proper_unit_for_byte_size(min_threshold));
 65     return true;
 66   }
 67 
 68   size_t bytes_allocated = _space_info->bytes_allocated_since_gc_start();
 69   if (bytes_allocated > threshold_bytes_allocated) {
 70     log_info(gc)("Trigger: Allocated since last cycle (" SIZE_FORMAT "%s) is larger than allocation threshold (" SIZE_FORMAT "%s)",
 71                  byte_size_in_proper_unit(bytes_allocated),           proper_unit_for_byte_size(bytes_allocated),
 72                  byte_size_in_proper_unit(threshold_bytes_allocated), proper_unit_for_byte_size(threshold_bytes_allocated));
 73     return true;
 74   }
 75 
 76   return ShenandoahHeuristics::should_start_gc();
 77 }
 78 
 79 void ShenandoahCompactHeuristics::choose_collection_set_from_regiondata(ShenandoahCollectionSet* cset,
 80                                                                         RegionData* data, size_t size,
 81                                                                         size_t actual_free) {
 82   // Do not select too large CSet that would overflow the available free space
 83   size_t max_cset = actual_free * 3 / 4;
 84 
 85   log_info(gc, ergo)("CSet Selection. Actual Free: " SIZE_FORMAT "%s, Max CSet: " SIZE_FORMAT "%s",
 86                      byte_size_in_proper_unit(actual_free), proper_unit_for_byte_size(actual_free),
 87                      byte_size_in_proper_unit(max_cset),    proper_unit_for_byte_size(max_cset));
 88 
 89   size_t threshold = ShenandoahHeapRegion::region_size_bytes() * ShenandoahGarbageThreshold / 100;
 90 
 91   size_t live_cset = 0;
 92   for (size_t idx = 0; idx < size; idx++) {
 93     ShenandoahHeapRegion* r = data[idx]._region;
 94     size_t new_cset = live_cset + r->get_live_data_bytes();
 95     if (new_cset < max_cset && r->garbage() > threshold) {
 96       live_cset = new_cset;
 97       cset->add_region(r);
 98     }
 99   }
100 }