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