Mercurial > hg > graal-compiler
view src/share/vm/gc_implementation/g1/g1MonitoringSupport.hpp @ 18027:9f169829d0e1
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author | asaha |
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date | Tue, 08 Jul 2014 13:25:13 -0700 |
parents | f2110083203d |
children | 63a4eb8bcd23 |
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/* * Copyright (c) 2011, 2013, Oracle and/or its affiliates. All rights reserved. * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER. * * This code is free software; you can redistribute it and/or modify it * under the terms of the GNU General Public License version 2 only, as * published by the Free Software Foundation. * * This code is distributed in the hope that it will be useful, but WITHOUT * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License * version 2 for more details (a copy is included in the LICENSE file that * accompanied this code). * * You should have received a copy of the GNU General Public License version * 2 along with this work; if not, write to the Free Software Foundation, * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA. * * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA * or visit www.oracle.com if you need additional information or have any * questions. * */ #ifndef SHARE_VM_GC_IMPLEMENTATION_G1_G1MONITORINGSUPPORT_HPP #define SHARE_VM_GC_IMPLEMENTATION_G1_G1MONITORINGSUPPORT_HPP #include "gc_implementation/shared/hSpaceCounters.hpp" class G1CollectedHeap; // Class for monitoring logical spaces in G1. It provides data for // both G1's jstat counters as well as G1's memory pools. // // G1 splits the heap into heap regions and each heap region belongs // to one of the following categories: // // * eden : regions that have been allocated since the last GC // * survivors : regions with objects that survived the last few GCs // * old : long-lived non-humongous regions // * humongous : humongous regions // * free : free regions // // The combination of eden and survivor regions form the equivalent of // the young generation in the other GCs. The combination of old and // humongous regions form the equivalent of the old generation in the // other GCs. Free regions do not have a good equivalent in the other // GCs given that they can be allocated as any of the other region types. // // The monitoring tools expect the heap to contain a number of // generations (young, old, perm) and each generation to contain a // number of spaces (young: eden, survivors, old). Given that G1 does // not maintain those spaces physically (e.g., the set of // non-contiguous eden regions can be considered as a "logical" // space), we'll provide the illusion that those generations and // spaces exist. In reality, each generation and space refers to a set // of heap regions that are potentially non-contiguous. // // This class provides interfaces to access the min, current, and max // capacity and current occupancy for each of G1's logical spaces and // generations we expose to the monitoring tools. Also provided are // counters for G1 concurrent collections and stop-the-world full heap // collections. // // Below is a description of how the various sizes are calculated. // // * Current Capacity // // - heap_capacity = current heap capacity (e.g., current committed size) // - young_gen_capacity = current max young gen target capacity // (i.e., young gen target capacity + max allowed expansion capacity) // - survivor_capacity = current survivor region capacity // - eden_capacity = young_gen_capacity - survivor_capacity // - old_capacity = heap_capacity - young_gen_capacity // // What we do in the above is to distribute the free regions among // eden_capacity and old_capacity. // // * Occupancy // // - young_gen_used = current young region capacity // - survivor_used = survivor_capacity // - eden_used = young_gen_used - survivor_used // - old_used = overall_used - young_gen_used // // Unfortunately, we currently only keep track of the number of // currently allocated young and survivor regions + the overall used // bytes in the heap, so the above can be a little inaccurate. // // * Min Capacity // // We set this to 0 for all spaces. // // * Max Capacity // // For jstat, we set the max capacity of all spaces to heap_capacity, // given that we don't always have a reasonable upper bound on how big // each space can grow. For the memory pools, we make the max // capacity undefined with the exception of the old memory pool for // which we make the max capacity same as the max heap capacity. // // If we had more accurate occupancy / capacity information per // region set the above calculations would be greatly simplified and // be made more accurate. // // We update all the above synchronously and we store the results in // fields so that we just read said fields when needed. A subtle point // is that all the above sizes need to be recalculated when the old // gen changes capacity (after a GC or after a humongous allocation) // but only the eden occupancy changes when a new eden region is // allocated. So, in the latter case we have minimal recalcuation to // do which is important as we want to keep the eden region allocation // path as low-overhead as possible. class G1MonitoringSupport : public CHeapObj<mtGC> { friend class VMStructs; G1CollectedHeap* _g1h; // jstat performance counters // incremental collections both young and mixed CollectorCounters* _incremental_collection_counters; // full stop-the-world collections CollectorCounters* _full_collection_counters; // young collection set counters. The _eden_counters, // _from_counters, and _to_counters are associated with // this "generational" counter. GenerationCounters* _young_collection_counters; // old collection set counters. The _old_space_counters // below are associated with this "generational" counter. GenerationCounters* _old_collection_counters; // Counters for the capacity and used for // the whole heap HSpaceCounters* _old_space_counters; // the young collection HSpaceCounters* _eden_counters; // the survivor collection (only one, _to_counters, is actively used) HSpaceCounters* _from_counters; HSpaceCounters* _to_counters; // When it's appropriate to recalculate the various sizes (at the // end of a GC, when a new eden region is allocated, etc.) we store // them here so that we can easily report them when needed and not // have to recalculate them every time. size_t _overall_reserved; size_t _overall_committed; size_t _overall_used; uint _young_region_num; size_t _young_gen_committed; size_t _eden_committed; size_t _eden_used; size_t _survivor_committed; size_t _survivor_used; size_t _old_committed; size_t _old_used; G1CollectedHeap* g1h() { return _g1h; } // It returns x - y if x > y, 0 otherwise. // As described in the comment above, some of the inputs to the // calculations we have to do are obtained concurrently and hence // may be inconsistent with each other. So, this provides a // defensive way of performing the subtraction and avoids the value // going negative (which would mean a very large result, given that // the parameter are size_t). static size_t subtract_up_to_zero(size_t x, size_t y) { if (x > y) { return x - y; } else { return 0; } } // Recalculate all the sizes. void recalculate_sizes(); // Recalculate only what's necessary when a new eden region is allocated. void recalculate_eden_size(); public: G1MonitoringSupport(G1CollectedHeap* g1h); // Unfortunately, the jstat tool assumes that no space has 0 // capacity. In our case, given that each space is logical, it's // possible that no regions will be allocated to it, hence to have 0 // capacity (e.g., if there are no survivor regions, the survivor // space has 0 capacity). The way we deal with this is to always pad // each capacity value we report to jstat by a very small amount to // make sure that it's never zero. Given that we sometimes have to // report a capacity of a generation that contains several spaces // (e.g., young gen includes one eden, two survivor spaces), the // mult parameter is provided in order to adding the appropriate // padding multiple times so that the capacities add up correctly. static size_t pad_capacity(size_t size_bytes, size_t mult = 1) { return size_bytes + MinObjAlignmentInBytes * mult; } // Recalculate all the sizes from scratch and update all the jstat // counters accordingly. void update_sizes(); // Recalculate only what's necessary when a new eden region is // allocated and update any jstat counters that need to be updated. void update_eden_size(); CollectorCounters* incremental_collection_counters() { return _incremental_collection_counters; } CollectorCounters* full_collection_counters() { return _full_collection_counters; } GenerationCounters* young_collection_counters() { return _young_collection_counters; } GenerationCounters* old_collection_counters() { return _old_collection_counters; } HSpaceCounters* old_space_counters() { return _old_space_counters; } HSpaceCounters* eden_counters() { return _eden_counters; } HSpaceCounters* from_counters() { return _from_counters; } HSpaceCounters* to_counters() { return _to_counters; } // Monitoring support used by // MemoryService // jstat counters // Tracing size_t overall_reserved() { return _overall_reserved; } size_t overall_committed() { return _overall_committed; } size_t overall_used() { return _overall_used; } size_t young_gen_committed() { return _young_gen_committed; } size_t young_gen_max() { return overall_reserved(); } size_t eden_space_committed() { return _eden_committed; } size_t eden_space_used() { return _eden_used; } size_t survivor_space_committed() { return _survivor_committed; } size_t survivor_space_used() { return _survivor_used; } size_t old_gen_committed() { return old_space_committed(); } size_t old_gen_max() { return overall_reserved(); } size_t old_space_committed() { return _old_committed; } size_t old_space_used() { return _old_used; } }; class G1GenerationCounters: public GenerationCounters { protected: G1MonitoringSupport* _g1mm; public: G1GenerationCounters(G1MonitoringSupport* g1mm, const char* name, int ordinal, int spaces, size_t min_capacity, size_t max_capacity, size_t curr_capacity); }; class G1YoungGenerationCounters: public G1GenerationCounters { public: G1YoungGenerationCounters(G1MonitoringSupport* g1mm, const char* name); virtual void update_all(); }; class G1OldGenerationCounters: public G1GenerationCounters { public: G1OldGenerationCounters(G1MonitoringSupport* g1mm, const char* name); virtual void update_all(); }; #endif // SHARE_VM_GC_IMPLEMENTATION_G1_G1MONITORINGSUPPORT_HPP