1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/src/share/vm/gc_implementation/g1/g1MonitoringSupport.hpp Wed Apr 27 01:25:04 2016 +0800
1.3 @@ -0,0 +1,269 @@
1.4 +/*
1.5 + * Copyright (c) 2011, 2013, Oracle and/or its affiliates. All rights reserved.
1.6 + * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
1.7 + *
1.8 + * This code is free software; you can redistribute it and/or modify it
1.9 + * under the terms of the GNU General Public License version 2 only, as
1.10 + * published by the Free Software Foundation.
1.11 + *
1.12 + * This code is distributed in the hope that it will be useful, but WITHOUT
1.13 + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
1.14 + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
1.15 + * version 2 for more details (a copy is included in the LICENSE file that
1.16 + * accompanied this code).
1.17 + *
1.18 + * You should have received a copy of the GNU General Public License version
1.19 + * 2 along with this work; if not, write to the Free Software Foundation,
1.20 + * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
1.21 + *
1.22 + * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
1.23 + * or visit www.oracle.com if you need additional information or have any
1.24 + * questions.
1.25 + *
1.26 + */
1.27 +
1.28 +#ifndef SHARE_VM_GC_IMPLEMENTATION_G1_G1MONITORINGSUPPORT_HPP
1.29 +#define SHARE_VM_GC_IMPLEMENTATION_G1_G1MONITORINGSUPPORT_HPP
1.30 +
1.31 +#include "gc_implementation/shared/hSpaceCounters.hpp"
1.32 +
1.33 +class G1CollectedHeap;
1.34 +
1.35 +// Class for monitoring logical spaces in G1. It provides data for
1.36 +// both G1's jstat counters as well as G1's memory pools.
1.37 +//
1.38 +// G1 splits the heap into heap regions and each heap region belongs
1.39 +// to one of the following categories:
1.40 +//
1.41 +// * eden : regions that have been allocated since the last GC
1.42 +// * survivors : regions with objects that survived the last few GCs
1.43 +// * old : long-lived non-humongous regions
1.44 +// * humongous : humongous regions
1.45 +// * free : free regions
1.46 +//
1.47 +// The combination of eden and survivor regions form the equivalent of
1.48 +// the young generation in the other GCs. The combination of old and
1.49 +// humongous regions form the equivalent of the old generation in the
1.50 +// other GCs. Free regions do not have a good equivalent in the other
1.51 +// GCs given that they can be allocated as any of the other region types.
1.52 +//
1.53 +// The monitoring tools expect the heap to contain a number of
1.54 +// generations (young, old, perm) and each generation to contain a
1.55 +// number of spaces (young: eden, survivors, old). Given that G1 does
1.56 +// not maintain those spaces physically (e.g., the set of
1.57 +// non-contiguous eden regions can be considered as a "logical"
1.58 +// space), we'll provide the illusion that those generations and
1.59 +// spaces exist. In reality, each generation and space refers to a set
1.60 +// of heap regions that are potentially non-contiguous.
1.61 +//
1.62 +// This class provides interfaces to access the min, current, and max
1.63 +// capacity and current occupancy for each of G1's logical spaces and
1.64 +// generations we expose to the monitoring tools. Also provided are
1.65 +// counters for G1 concurrent collections and stop-the-world full heap
1.66 +// collections.
1.67 +//
1.68 +// Below is a description of how the various sizes are calculated.
1.69 +//
1.70 +// * Current Capacity
1.71 +//
1.72 +// - heap_capacity = current heap capacity (e.g., current committed size)
1.73 +// - young_gen_capacity = current max young gen target capacity
1.74 +// (i.e., young gen target capacity + max allowed expansion capacity)
1.75 +// - survivor_capacity = current survivor region capacity
1.76 +// - eden_capacity = young_gen_capacity - survivor_capacity
1.77 +// - old_capacity = heap_capacity - young_gen_capacity
1.78 +//
1.79 +// What we do in the above is to distribute the free regions among
1.80 +// eden_capacity and old_capacity.
1.81 +//
1.82 +// * Occupancy
1.83 +//
1.84 +// - young_gen_used = current young region capacity
1.85 +// - survivor_used = survivor_capacity
1.86 +// - eden_used = young_gen_used - survivor_used
1.87 +// - old_used = overall_used - young_gen_used
1.88 +//
1.89 +// Unfortunately, we currently only keep track of the number of
1.90 +// currently allocated young and survivor regions + the overall used
1.91 +// bytes in the heap, so the above can be a little inaccurate.
1.92 +//
1.93 +// * Min Capacity
1.94 +//
1.95 +// We set this to 0 for all spaces.
1.96 +//
1.97 +// * Max Capacity
1.98 +//
1.99 +// For jstat, we set the max capacity of all spaces to heap_capacity,
1.100 +// given that we don't always have a reasonable upper bound on how big
1.101 +// each space can grow. For the memory pools, we make the max
1.102 +// capacity undefined with the exception of the old memory pool for
1.103 +// which we make the max capacity same as the max heap capacity.
1.104 +//
1.105 +// If we had more accurate occupancy / capacity information per
1.106 +// region set the above calculations would be greatly simplified and
1.107 +// be made more accurate.
1.108 +//
1.109 +// We update all the above synchronously and we store the results in
1.110 +// fields so that we just read said fields when needed. A subtle point
1.111 +// is that all the above sizes need to be recalculated when the old
1.112 +// gen changes capacity (after a GC or after a humongous allocation)
1.113 +// but only the eden occupancy changes when a new eden region is
1.114 +// allocated. So, in the latter case we have minimal recalcuation to
1.115 +// do which is important as we want to keep the eden region allocation
1.116 +// path as low-overhead as possible.
1.117 +
1.118 +class G1MonitoringSupport : public CHeapObj<mtGC> {
1.119 + friend class VMStructs;
1.120 +
1.121 + G1CollectedHeap* _g1h;
1.122 +
1.123 + // jstat performance counters
1.124 + // incremental collections both young and mixed
1.125 + CollectorCounters* _incremental_collection_counters;
1.126 + // full stop-the-world collections
1.127 + CollectorCounters* _full_collection_counters;
1.128 + // young collection set counters. The _eden_counters,
1.129 + // _from_counters, and _to_counters are associated with
1.130 + // this "generational" counter.
1.131 + GenerationCounters* _young_collection_counters;
1.132 + // old collection set counters. The _old_space_counters
1.133 + // below are associated with this "generational" counter.
1.134 + GenerationCounters* _old_collection_counters;
1.135 + // Counters for the capacity and used for
1.136 + // the whole heap
1.137 + HSpaceCounters* _old_space_counters;
1.138 + // the young collection
1.139 + HSpaceCounters* _eden_counters;
1.140 + // the survivor collection (only one, _to_counters, is actively used)
1.141 + HSpaceCounters* _from_counters;
1.142 + HSpaceCounters* _to_counters;
1.143 +
1.144 + // When it's appropriate to recalculate the various sizes (at the
1.145 + // end of a GC, when a new eden region is allocated, etc.) we store
1.146 + // them here so that we can easily report them when needed and not
1.147 + // have to recalculate them every time.
1.148 +
1.149 + size_t _overall_reserved;
1.150 + size_t _overall_committed;
1.151 + size_t _overall_used;
1.152 +
1.153 + uint _young_region_num;
1.154 + size_t _young_gen_committed;
1.155 + size_t _eden_committed;
1.156 + size_t _eden_used;
1.157 + size_t _survivor_committed;
1.158 + size_t _survivor_used;
1.159 +
1.160 + size_t _old_committed;
1.161 + size_t _old_used;
1.162 +
1.163 + G1CollectedHeap* g1h() { return _g1h; }
1.164 +
1.165 + // It returns x - y if x > y, 0 otherwise.
1.166 + // As described in the comment above, some of the inputs to the
1.167 + // calculations we have to do are obtained concurrently and hence
1.168 + // may be inconsistent with each other. So, this provides a
1.169 + // defensive way of performing the subtraction and avoids the value
1.170 + // going negative (which would mean a very large result, given that
1.171 + // the parameter are size_t).
1.172 + static size_t subtract_up_to_zero(size_t x, size_t y) {
1.173 + if (x > y) {
1.174 + return x - y;
1.175 + } else {
1.176 + return 0;
1.177 + }
1.178 + }
1.179 +
1.180 + // Recalculate all the sizes.
1.181 + void recalculate_sizes();
1.182 + // Recalculate only what's necessary when a new eden region is allocated.
1.183 + void recalculate_eden_size();
1.184 +
1.185 + public:
1.186 + G1MonitoringSupport(G1CollectedHeap* g1h);
1.187 +
1.188 + // Unfortunately, the jstat tool assumes that no space has 0
1.189 + // capacity. In our case, given that each space is logical, it's
1.190 + // possible that no regions will be allocated to it, hence to have 0
1.191 + // capacity (e.g., if there are no survivor regions, the survivor
1.192 + // space has 0 capacity). The way we deal with this is to always pad
1.193 + // each capacity value we report to jstat by a very small amount to
1.194 + // make sure that it's never zero. Given that we sometimes have to
1.195 + // report a capacity of a generation that contains several spaces
1.196 + // (e.g., young gen includes one eden, two survivor spaces), the
1.197 + // mult parameter is provided in order to adding the appropriate
1.198 + // padding multiple times so that the capacities add up correctly.
1.199 + static size_t pad_capacity(size_t size_bytes, size_t mult = 1) {
1.200 + return size_bytes + MinObjAlignmentInBytes * mult;
1.201 + }
1.202 +
1.203 + // Recalculate all the sizes from scratch and update all the jstat
1.204 + // counters accordingly.
1.205 + void update_sizes();
1.206 + // Recalculate only what's necessary when a new eden region is
1.207 + // allocated and update any jstat counters that need to be updated.
1.208 + void update_eden_size();
1.209 +
1.210 + CollectorCounters* incremental_collection_counters() {
1.211 + return _incremental_collection_counters;
1.212 + }
1.213 + CollectorCounters* full_collection_counters() {
1.214 + return _full_collection_counters;
1.215 + }
1.216 + GenerationCounters* young_collection_counters() {
1.217 + return _young_collection_counters;
1.218 + }
1.219 + GenerationCounters* old_collection_counters() {
1.220 + return _old_collection_counters;
1.221 + }
1.222 + HSpaceCounters* old_space_counters() { return _old_space_counters; }
1.223 + HSpaceCounters* eden_counters() { return _eden_counters; }
1.224 + HSpaceCounters* from_counters() { return _from_counters; }
1.225 + HSpaceCounters* to_counters() { return _to_counters; }
1.226 +
1.227 + // Monitoring support used by
1.228 + // MemoryService
1.229 + // jstat counters
1.230 + // Tracing
1.231 +
1.232 + size_t overall_reserved() { return _overall_reserved; }
1.233 + size_t overall_committed() { return _overall_committed; }
1.234 + size_t overall_used() { return _overall_used; }
1.235 +
1.236 + size_t young_gen_committed() { return _young_gen_committed; }
1.237 + size_t young_gen_max() { return overall_reserved(); }
1.238 + size_t eden_space_committed() { return _eden_committed; }
1.239 + size_t eden_space_used() { return _eden_used; }
1.240 + size_t survivor_space_committed() { return _survivor_committed; }
1.241 + size_t survivor_space_used() { return _survivor_used; }
1.242 +
1.243 + size_t old_gen_committed() { return old_space_committed(); }
1.244 + size_t old_gen_max() { return overall_reserved(); }
1.245 + size_t old_space_committed() { return _old_committed; }
1.246 + size_t old_space_used() { return _old_used; }
1.247 +};
1.248 +
1.249 +class G1GenerationCounters: public GenerationCounters {
1.250 +protected:
1.251 + G1MonitoringSupport* _g1mm;
1.252 +
1.253 +public:
1.254 + G1GenerationCounters(G1MonitoringSupport* g1mm,
1.255 + const char* name, int ordinal, int spaces,
1.256 + size_t min_capacity, size_t max_capacity,
1.257 + size_t curr_capacity);
1.258 +};
1.259 +
1.260 +class G1YoungGenerationCounters: public G1GenerationCounters {
1.261 +public:
1.262 + G1YoungGenerationCounters(G1MonitoringSupport* g1mm, const char* name);
1.263 + virtual void update_all();
1.264 +};
1.265 +
1.266 +class G1OldGenerationCounters: public G1GenerationCounters {
1.267 +public:
1.268 + G1OldGenerationCounters(G1MonitoringSupport* g1mm, const char* name);
1.269 + virtual void update_all();
1.270 +};
1.271 +
1.272 +#endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1MONITORINGSUPPORT_HPP
