jdk8-mips64-public/hotspot: src/share/vm/gc_implementation/g1/g1MonitoringSupport.hpp@8aae2050e83e (annotated)

src/share/vm/gc_implementation/g1/g1MonitoringSupport.hpp@8aae2050e83e (annotated)

src/share/vm/gc_implementation/g1/g1MonitoringSupport.hpp

Mon, 07 Nov 2011 22:11:12 -0500

author: tonyp
date: Mon, 07 Nov 2011 22:11:12 -0500
changeset 3268: 8aae2050e83e
parent 3180: 81aa07130d30
child 3337: 41406797186b
permissions: -rw-r--r--

7092309: G1: introduce old region set
Summary: Keep track of all the old regions in the heap with a heap region set.
Reviewed-by: brutisso, johnc

 /*
  * Copyright (c) 2011, 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. We could consider setting the old
 //    min capacity to the min capacity of the heap (see 7078465).
 //
 // * Max Capacity
 //
 //    For jstat, we set the max capacity of all spaces to heap_capacity,
 //    given that we don't always have a reasonably upper bound on how big
 //    each space can grow. For the memory pools, we actually make the max
 //    capacity undefined. We could consider setting the old max capacity
 //    to the max capacity of the heap (see 7078465).
 //
 // 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 {
   friend class VMStructs;
   G1CollectedHeap* _g1h;
   // jstat performance counters
   //  incremental collections both fully and partially young
   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;
   size_t _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
   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

Mercurial > jdk8-mips64-public > hotspot / annotate

src/share/vm/gc_implementation/g1/g1MonitoringSupport.hpp@8aae2050e83e (annotated)

src/share/vm/gc_implementation/g1/g1MonitoringSupport.hpp